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Core Ideas - Earth Science, K-12 Framework

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Core Ideas - Earth Science, K-12 Framework

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2. Providence Canyon

Protect Providence Canyon

Carving or climbing on canyon walls is punishable by fine. Help us protect the canyon for future generations.

Stay on trails and behind fences because canyon edges may collapse.

Dogs are welcome on trails and must remain on 6-foot leash.

"Uncover the layers of 'Georgia’s Little Grand Canyon' as you navigate the unusual geological formations created by erosion of the Coastal Plain after years of poor agricultural practices, hike miles of sandy nature trails, and gaze at dark skies while camping at Providence Canyon State Park."

Georgia’s “Little Grand Canyon” is a testament to the power of man’s influence on the land. Massive gullies as deep as 150 feet were caused simply by poor farming practices during the 1800s, yet today they make some of the prettiest photographs within the state. The rare Plumleaf Azalea grows only in this region and blooms during July and August when most azaleas have lost their color. The canyon soil’s pink, orange, red and purple hues make a beautiful natural painting at this quiet park.

Visitors can enjoy views of the canyons from the rim trail, taking care to stay behind fences and off the fragile canyon edge. Hikers who explore the deepest canyons will usually find a thin layer of water along the trail, indication of the water table below. Guests who hike to canyons 4 and 5 may want to join the Canyon Climbers Club. Backpackers can stay overnight along the backcountry trail which highlights portions of the canyon and winds through mixed forest. Camping, cottages and efficiency units are available nearby at Florence Marina State Park on 45,000 acre Lake Walter F. George.

Reservations, Accommodations & Facilities

1,003 Acres

2 Picnic Shelters (Before making reservations, call park for capacity limits.)

3 Pioneer Campsites (Before making reservations, call park for capacity limits.)

6 Backcountry Campsites

Museum

Visitor Center

Things To Do & See

Astronomy and Geology Programs

Hiking

Picnicking

Canyon Climbers Club

Nearby Attractions

Florence Marina State Park - 9 miles away - camping and cabins available.

George T. Bagby State Park

Kolomoki Mounds State Park

Hannahatchee Creek WMA

Lake Walter F. George WMA

Eufaula National Wildlife Refuge

Flint RiverQuarium

Historic Westville

Albany, GA

Americus-Sumter County, GA

Columbus, GA

Pine Mountain, GA

Macon, GA

Rome, GA

In The News

The Secrets Of Providence Canyon Georgia's Little Grand Canyon - 365 Atlanta Traveler

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Providence Canyon State Park | Department Of Natural Resources Division

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Protect Providence Canyon Carving or climbing on canyon walls is punishable by fine.

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Providence Canyon - New Georgia Encyclopedia

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Providence Canyon - New Georgia Encyclopedia

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Providence Canyon is a network of gorges

in southwest Georgia created by the erosion of soft, multicolored soils. Often called "Georgia's Little Grand Canyon," Providence Canyon consists of several chasms, plateaus, cliffs, and pinnacles. Erosion has exposed the geologic record of several million years within its walls, and minerals have stained the sediments, creating a display of colors that range from white to various shades of pink, purple, red, brown, yellow, and black.

Identified by the Georgia Department of Natural Resources as one of the state's "Seven Wonders," the site is protected by Providence Canyon State Park, located approximately 150 miles southwest of Atlanta, in Stewart County. The 1,109-acre park includes 16 canyons, some as deep as 150 feet, all of which together make up the site known as Providence Canyon. From a trail along the rim, several overlooks offer views of the canyon walls, in which forty-three different colors of sands have been identified.

The rare plumleaf azalea ( Rhododendron prunifolium), found only in southwestern Georgia and eastern Alabama, blooms in Providence Canyon from mid to late summer, in the largest known wild colony of this species.

Although

the appearance of Providence Canyon evokes comparisons to the landscape of the American Southwest, its history is unique. The canyon consists of huge gullies sculpted of soil, not by the action of a river or stream but by rainwater runoff from farm fields.

Historical accounts indicate that the canyon began forming in the early 1800s as the result of poor soil-management practices. Native forest cover had been cleared so the land could be farmed, and early-nineteenth-century farmers in this region took no measures to avoid soil erosion. Small gullies formed and rapidly grew deeper and more extensive. By 1850 ditches three to five feet deep had been cut into the land, further concentrating runoff and increasing the rate of erosion.

Although the formation of Providence Canyon might be seen as the result of a distinct lack of providence, its name apparently came from Providence Methodist Church, established around 1832. A church building and a schoolhouse originally stood on land that now lies between the main gorges of the canyon. In 1859 a new church building was erected across the road from the canyon; it still stands and is occasionally used for special services.

Providence Canyon, which lies in the Coastal Plain region of Georgia, has been carved from unconsolidated sediments deposited by water in ancient streams, seas, deltas, and coastal beaches between 59 and 74 million years ago. Geologists separate the sediments forming the canyon into four major geologic formations: Baker Hill, Clayton, Providence, and Ripley.

The Baker Hill formation is the youngest and forms the uppermost part of soils in Providence Canyon State Park. Deposited about 59 to 62 million years ago during the Paleogene period, this formation does not appear in the canyon walls, but the entrance road to the park and the Interpretive Center lie on top of it.

The Clayton formation, visible in the top part of the canyon walls, also was deposited during the Paleogene period, about 63 to 65 million years ago, just after the age of the dinosaurs. Its fairly coarse sand is a reddish color, caused by the presence of iron oxide. Near the base of this formation, iron oxides have precipitated into a thin, dark layer of iron ore, which has been mined in some areas outside the park.

The

Providence formation, also known as the Providence Sand, makes up most of the canyon walls. One hundred and nineteen feet thick, it was deposited during the Cretaceous period, about 67 to 70 million years ago. The upper layer of this formation consists of very fine sand mixed with a white clay called kaolin. The middle layer is coarser-grained and more colorful, with crossbeds stained yellow by limonite and purple by manganese. The lowest and oldest layer is a black and yellow mica-rich clay. This part of the formation is known as the Perote member and is visible near the bottom of the canyon.

The Ripley formation forms the canyon floor. Deposited during the Cretaceous period, about 70 to 74 million years ago, it is orange in color, and its composition varies from clay to a massively bedded sand. This formation is the richest of the layers in fossils, but it is poorly exposed and, in the park, mostly overgrown.

Providence Canyon continues to erode and change due to surface water runoff and the undercutting force of groundwater. The clay content of sediments in the floor of the canyon makes it more resistant, and the growth of pine trees, laurel bushes, and other vegetation helps to stabilize the soil, reducing the rate of vertical erosion. Lateral erosion, however, continues, and because of the soft nature of the upper soils, changes can happen very rapidly. Gorges grow larger, and the rim of the canyon often shows signs of crumbling and receding. Pinnacles gradually decrease in size and can disappear overnight in heavy rains.

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Providence Canyon is a network of gorges in southwest Georgia created by the erosion of soft, multicolored soils. Often called "Georgia's Little Grand Canyon," Providence Canyon consists of several chasms, plateaus, cliffs, and pinnacles.

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Top 10 Things to Do in and Around the Grand Canyon

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Top 10 Things to Do in and Around the Grand Canyon

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Top 10 Things To Do In And Around The Grand Canyon

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Gneiss, however, is a "garbage can" of a word with a wide definition of that includes an astonishing assortment of rocks displaying this foliation that formed in a myriad of metamorphic environments. Gneiss can form at as low a temperature as 320°C with pressures of 10 GPa, but this occurs only very deep-more than 30 km-in the mantle. More commonly it forms at ~600°C at 2 to 4 GPa, a realm that is common in orogenies (mountain building events) at depths of 8 to 12 km. Minerals that form in this environment include hornblende, pyroxene and garnet. The sheet silicates (micas like muscovite and biotite) are less stable in these environments and their molecules change as a solid solution into a form that is more stable in this high grade temperature and pressure environment. These new minerals form perpendicular to the pressure gradient and this is what makes the alternating light and dark lines.

A common misconception holds that granite is the original source of gneiss. While this can be true, almost any rock subjected to high-grade (high heat and pressure) regional metamorphism can form gneiss.

Gneiss derived from igneous rock (like granite) is termed orthogneiss. Gneiss derived from sedimentary rock is termed paragneiss.

These words reflect the misconception as " ortho" means straight, upright, rectangular, regular; true, correct, proper; while " para"means alongside, beyond; altered; contrary; irregular, abnormal.

Modifiers often precede the word to indicate the origin or a dominant mineral in the rock. Granite or diorite gneiss is metamorphosed from those rocks. Garnet or biotite gneiss are abundant in those minerals.

Here is a thorough, if tortured, description of migmatite, with words not defined in the text asterisked and defined below:

"A migmatite is a banded, granular metamorphic rock that contains light coloured bands with evidence for partial melting. Migmatites comprise leucosome* bands, comprised largely of quartz and feldspar, which crystallised from partial melts or segregated metamorphic fluids, and mesosomes* and melanosomes* that represent the residues of partial melting and are often dominated by mafic components such as amphibole, pyroxene and biotite and are often finer-grained than leucosomes. The terms neosome and palaeosome are used to denote components of the migmatite that have experience significant and little partial melting respectively.

"Migmatites have usually experienced significant ductile deformation and exhibit incoherent folding with ptygmatic folds restricted to individual layers and extensive boudinage. Clast-like bodies can occur within migmatites and are composed of restite, solid blocks of partial melt residue, that do not undergo ductile deformation. Often leucosomes in migmatites have rims of mafic minerals known as selvages that form by reaction with the melt or a coexisting fluid. Migmatites are sometimes sub-divided into metatexites, that have experienced low degrees of partial melting, or diatexites, that have experienced high degrees. Metatexites can also often be termed hornfels or gniess and are prefixed with "migmatised".

"Migmatites form by high temperature regional and/or thermal metamorphism of protolith rocks where temperatures are sufficient to cause partial melting. They are often associated with granulites and gneisses, and often are spatially associated to granitic intrusions. The partial melting of crustal rocks (or anatexis), which results in migmatites, is responsible for the generation of many granite magmas. Partial melting within migmatites leads to the formation of a banded rock by segregation of viscous partial melts and rigid resistite due to differential stress." [ Imperial College Rock Library]

* leucosomes are the lightest colored parts of a migmatite
* mesosomes are intermediate between the dark and light colored parts of a migmatite and usually an unmodified remnant of the protolith; synonymous with paleosome.
* melanosomes are the darkest parts of a migmatite

Finnish petrologist Jakob Johannes Sederholm (1863 - 1934) studied the strange mix of metamorphic and granitic rocks in the Precambrian Baltic Shield and coined the word from the Greek μιγμα migma, a mixture.

Migmatites form where the pressure and temperature regime tease with the melting point of the rock; sometimes above, sometimes below. The temperature must be at least 800°C but less than ~1,200°C. This simplifies a very complex world as all the minerals in the rock don't have the same melting point. Some will completely melt, others become plastic and yet others still completely solid and undergoing solid solution metamorphism. With viscous meeting solid and liquid, very strange patterns of minerals form, especially when the viscous are forced into the liquid or fractures in the solid and the resistance creates very odd shapes of ptygmatic folds and boudins.

Where does this sort of environment exist? Plate tectonics gives us the answer. When continents collide, especially large continents like Laurasia and Gondwanaland, massive amounts of pressure develop in many directions as the rocks pile on top of each other and fold from incredible lateral force. Migmatites form fairly deep in the earth under these gigantic collisions, usually at a depth of at least three kilometers, often much greater. But they can't be deep enough where the temperature and pressure will cause all the rock to melt. It is the strange world of "almost melting". Perhaps a poor analogy would be very slowly heating a wax candle until it is soft enough to bend, then pushing on it from several directions. If two different colors melt at different temperatures, one would melt and one would remain solid. Imagine what this would look like if you pushed on the mix from several directions at once.

The Arabia Mountain Migmatite
Here are three modern technical descriptions of the formation that includes the rocks of Arabia Mountain in chronological order.

"Although the name Arabia Mountain Migmatite was designated by Grant and others (1980) for a common variety of Lithonia Gneiss, in this report the rocks are informally named Arabia Mountain migmatite facies of Lithonia Gneiss. Rocks previously mapped as Norcross Gneiss are now thought to be a facies of Lithonia Gneiss; Norcross Gneiss is abandoned and its rocks assigned to Lithonia Gneiss. Recent geologic mapping, petrographic and geochemical studies, and some geochronological data of rocks called Lithonia Gneiss, Arabia Mountain migmatite facies within Lithonia Gneiss around Mount Arabia, "Odessadale Gneiss" in central GA (R.L. Atkins, unpub. mapping) and Farmville Metagranite of Opelika Complex in eastern AL have shown that 1) they are part of the same complex unit, 2) that several textural varieties are common to all of them in outcrop, 3) that they all occupy the same structural or stratigraphic interval, 4) that they have approximately the same mineral and chemical compositions, and 5) that their ages range between about 380 to 360 Ma (Middle to Late Devonian). Because of uncertainties in Pb-U zircon age data, because Rb-Sr and K-Ar ages could have been affected by metamorphism, and because overall sampling has been limited, all the gneisses are assigned an Ordovician to Devonian age although it is probably the age of the neosome; age of the paleosome of Lithonia Gneiss may be as old as Middle Proterozoic or as young as Middle Ordovician."

Crawford, T.J., M.W. Higgins, R.F. Crawford, R.L. Atkins, J.H. Medlin, & T.W. Stern. 1999. Revision of stratigraphic nomenclature in the Atlanta, Athens, and Cartersville 30- x 60-minute quadrangles, Georgia. Georgia Geological Survey Bulletin, no. 130, 45 p.

Higgins et al description of the Lithonia gneiss from their Atlanta quadrangle map:

"Dl Lithonia Gneiss, undivided (Devonian)-Lithonia Gneiss is a complex of metagranites and granitic gneisses. The most common rock type is a light-gray to grayish-white, medium-grained, poorly foliated metagranite that is cut by numerous pegmatite and aplite dikes and sills of several generations; dikes of different generations crosscut older dikes. This rock type probably forms about 80 to 90 percent of all rocks mapped as Lithonia Gneiss in the Athens quadrangle, whereas in the Atlanta and Griffin quadrangles, it may form only about 40 to 50 percent. The remainder of rocks mapped as Lithonia Gneiss are migmatite gneiss that belong to the Mount Arabia Migmatite of Grant and others (1980; also see Covert, 1986; and Size and Khairallah, 1989), which is included in this unit on this map. The Mount Arabia Migmatite of Grant and others (1980) is a light-gray to whitish-gray, medium-grained muscovite-biotite-microcline-oligoclase-quartz gneiss with well-defined, contorted, generally 3-mm- to 1-cm-thick gneissic layering. The migmatite gneiss is the prevalent rock type in Lithonia Gneiss near its edges, whereas the metagranite is far more prevalent away from the edges of most outcrop areas of Lithonia Gneiss. Garnet segregations in lenses as large as 2 m by 2 m are locally present in the migmatite gneiss. Scattered xenoliths, mainly of amphibolite, are present in the metagranite and the migmatite gneiss, but are probably more abundant in the migmatite gneiss. Pavement outcrops are characteristic of both the metagranite and the migmatite gneiss, and where deeply weathered both form light-whitish-yellow sandy soils. Both the metagranite and the migmatite gneiss are extensively quarried for crushed-stone aggregate and curbstone, and the migmatite gneiss is extensively quarried for monumental stone."

Higgins, M.W., T.J. Crawford, R.L. Atkins & R.F. Crawford. 2003. Geologic map of the Atlanta 30' x 60' quadrangle, Georgia. Scientific Investigations Map 2602. U.S. Geologic Survey, Reston, VA.

Three years after the publication of the map, Ralph Crawford mapped the Lawrenceville quadrangle and makes these comments on the Lithonia Gneiss and its Mount Arabia migmatite member:

"The Lithonia Gneiss, which underlies large areas in the quadrangle, has been mapped to the southwest into Alabama and into the Ordovician Farmville Granite (~477 Ma). The granitoid phase of the Lithonia is an Ordovician batholith that intruded the Stonewall Gneiss producing the Mount Arabia Migmatite. The Stonewall crops out around the edges of the Lithonia granitoid phase and in local roof pendants. The migmatite appears to occur only around the edges of the Lithonia and around roof pendants of Stonewall Gneiss, whereas the Lithonia away from any Stonewall is mostly metamorphosed granitoid. The aluminous schist and Chattahoochee Palisades Quartzite of the Sandy Springs Group structurally overlie the Lithonia, the Stonewall, and the Allatoona allochthon as well, on the Sandy Springs fault. The Lithonia, its country rock, the Stonewall Gneiss, and overlying Sandy Springs rocks constitute a mantled gneiss dome assemblage. The aluminous schist and quartzite are interpreted to have been deposited unconformably upon the Lithonia and the other units and were metamorphosed with the Lithonia and thrust across it. Sandy Springs Group rocks also border the Dacula shear zone on the northwest and probably dip beneath the zone and the Lithonia Gneiss."

Crawford, R.F. 2006. Geologic map of the Lawrenceville 7.5-minute quadrangle map, Georgia. The Geological Society of America Southeastern Section-55th Annual Meeting (23-24 March 2006) Paper No. 33-20.

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Gneiss, however, is a "garbage can" of a word with a wide definition of that includes an astonishing assortment of rocks displaying this foliation that formed in a myriad of metamorphic environments. Gneiss can form at as low a temperature as 320°C with pressures of 10 GPa, but this occurs only very deep-more than 30 km-in the mantle.

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The Arabia Mountain National Heritage Area spans hundreds of scenic acres just east of Atlanta, from breathtaking mountain summits and wildlife-filled grassy meadows to small, glassy lakes and wide-open fields of rock and boulders. The NHA includes two of our favorite hiking, running, and cycling destinations, Panola Mountain State Park and Arabia Mountain Nature Preserve. Despite its location just minutes east of downtown Atlanta, this is one fantastic destination for outdoor exploration, seemingly worlds away from the nearby urban cityscape.

Arabia Mountain's massive exposed granite faces reveal its history as a quarry: cut granite slabs, drilled cores, and abandoned structures scatter along the mountain's many trails. Today, Arabia is a serene world of exposed granite punctuated by lakes, wetlands, grassy meadows, and young forests. It's one of the most popular hiking areas in metro Atlanta, and makes for a great urban escape.

Unlike its nearby neighbor, Panola Mountain was spared from granite production and is now home to a stunning, fragile ecosystem of rare plants, mosses, and lichens. And while access to the actual Panola Mountain summit is usually restricted, hikers can explore this beautiful landscape by way of a guide-led twilight tour.

Arabia Mountain & Panola Mountain trails: our favorite hikes

Throughout the National Heritage Area, over 30 miles of paved and unpaved trails wind through rugged mountain summits and wetlands, exploring diverse lichens and mosses, flowers and trees, and wildlife habitats. These are our favorite hiking, running and cycling trails at these two mountains, and they're all equally worthy of an afternoon of exploration. If you're in the area with energy - and daylight - to burn, combine two or more trails to explore this park's incredible diversity of sights and landscapes.

Please Remember

Always leave no trace, pack out everything you pack in, and if you see trash, pick it up and pack it out.

Stay on the marked trail, tell someone where you're going, pack safety and wayfinding essentials, and don't rely on a mobile phone to find your way. Please always practice good trail etiquette. And before you go, always check the trailhead kiosk, official maps, and the park or ranger office for notices of changed routes, trail closures, safety information, and restrictions.

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Arabia Mountain & Panola Mountain: Our favorite hikes

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The Arabia Mountain National Heritage Area spans hundreds of scenic acres just east of Atlanta, from breathtaking mountain summits and wildlife-filled grassy meadows to small, glassy lakes and wide-open fields of rock and boulders. The NHA includes two of our favorite hiking, running, and cycling destinations, Panola Mountain State Park and Arabia Mountain Nature Preserve.

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Natural History of Stone Mountain - Arabia Mountain Natural Heritage Center

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Natural History of Stone Mountain - Arabia Mountain Natural Heritage Center

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While not in the Arabia Mountain National Heritage Area, Stone Mountain is the most prominent example of the monadnock ecosystem in the Atlanta area. Monadnocks - large outcrops of rock that has withstood erosion while the surrounding landscape has weathered away - dot the Atlanta metro, and include Kennesaw Mountain, Arabia Mountain, and Stone Mountain.

The granite of Arabia and Stone Mountains, especially, proved useful in quarry operations in the 19th and 20th centuries, leading to the growth of the Georgia Piedmont's quarry industry. While humans have interacted with the mountain for millennia (as far back as 9,000 years ago), it also contains a rich natural history.

Prior to human activity, Stone Mountain's massive size likely made it the most biodiverse of the granite outcrops in this area. Even today, dozens of wildflowers grow on its slopes, including the iconic yellow daisy ( Helianthus porteri). The daisy is sometimes called the Stone Mountain daisy because it is often associated with the monadnock.

Geologically, Stone Mountain was formed at the same time as the Blue Ridge Mountains, around 300 million years ago. Panola Mountain formed around the same time, while Arabia Mountain formed 400 million years ago. All three monadnocks are plutons, meaning that a bubble of magma welled up from beneath the earth's crust and hardened over time. It is this "bubble" that we see today, as the ground around it has eroded away.

The Arabia Mountain National Heritage Area works with the Stone Mountain Memorial Association to promote the ecology and geology of the region with several events throughout the year, including Monadnock Madness and Daisy Days. You can reach Stone Mountain Park for personal hiking or events by taking Exit 8 on US Highway 78, just east of Atlanta.

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While not in the Arabia Mountain National Heritage Area, Stone Mountain is the most prominent example of the monadnock ecosystem in the Atlanta area. Monadnocks - large outcrops of rock that has withstood erosion while the surrounding landscape has weathered away - dot the Atlanta metro, and include Kennesaw Mountain, Arabia Mountain, and Stone Mountain.

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Visitors may be surprised to discover just how easy it is to access the many natural landforms in "The Peach State." Besides its 100-mile stretch of Atlantic Ocean coastline, Georgia has numerous lakes, rivers and wetlands, mountains and the world's most massive single block of granite.

Coastal Georgia

Along the Atlantic coast, explore landforms ranging from beaches, marshlands, hammocks and islands. Barrier islands, like "the Golden Isles" of St. Simons Island, Sea Island, Little St. Simons Island and Jekyll Island, are vacation destinations, but development hides the fact they protect mainland communities from storm surges. To best observe these natural landforms, visit Cumberland Island National Seashore on Cumberland Island. The largest of the state's barrier islands, Cumberland Island is accessible by ferry, and visitor attendance is limited to protect the undeveloped ecosystem. Visitors can stay at the historic Grayfield Inn or the park service's Sea Camp campground while checking out the island's maritime forest, wetlands, marshes and sandy beaches.

Lakes, Rivers and Wetlands

To view an abundance of landforms in one location, head to southeast Georgia, home of the Okefenokee Swamp, the most extensive fresh- and blackwater swamp in North America. Once part of the ocean, the Okefenokee is a peat-filled bog set in a sandy depression in the earth's surface. Today, the Okefenokee National Wildlife Refuge encompasses this landform. Explore the swamp's cypress forests, canals and prairies by canoe trail, boardwalk hikes and even by bicycle or car. The Suwannee River and the St. Marys River, two of Georgia's 33 rivers, originate in the swamp. The Okefenokee is also home to 60 named lakes, with Billy Lake the largest at 60 acres.

Mountains

Travel 90 miles north of Atlanta to explore the southern Appalachians and Georgia's tallest mountain peak in the Chattahoochee-Oconee National Forest. Atop the summit of Brasstown Bald, 4,784 feet above sea level, the visitor information center offers ranger programs, exhibits, videos and information on hiking and recreation. Just 15 minutes east of Atlanta, explore Panola Mountain State Park, a national natural landmark that's part of the Arabia Mountain National Heritage Area. Guided tours are the only way to explore Panola, as the park limits trail usage to protect rare plant species.

Stone Mountain

Stone Mountain isn't a mountain per se, but a granite pluton -- an ancient magma chamber visible on the earth's surface thanks to uplift and erosion. Rising 825 feet above the surrounding landscape, at its highest point Stone Mountain is 1,683 feet above sea level. Just 18 miles east of downtown Atlanta, Stone Mountain has developed into a theme park complete with human-made landmarks, seasonal thrill rides and outdoor recreation. The Confederate Memorial Carving, depicting Robert E. Lee, "Stonewall" Jackson and Jefferson Davis, looks small from a distance but covers 3 acres of one side of the mountain. Visitors can travel to the summit by cable car or enjoy a 5-mile-long train ride around its base.

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Visitors may be surprised to discover just how easy it is to access the many natural landforms in "The Peach State." Besides its 100-mile stretch of Atlantic Ocean coastline, Georgia has numerous lakes, rivers and wetlands, mountains and the world's most massive single block of granite.

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Granite outcrops are exposed granitic rocks, found in the Piedmont and Appalachian Mountain regions. These outcrops weather in characteristic patterns and provide unusual habitats where a unique set of plants and animals have adapted. It is estimated that more than 90 percent of the approximately 12,000 acres of exposed granite in the Southeast is located in Georgia, including Stone Mountain, the largest of the Piedmont outcrops.

Granite Outcrop at Panola Mountain

Photograph by Melinda Smith Mullikin, New Georgia Encyclopedia

Geological Age and Weathering

Geologists estimate that most of the granitic rocks that outcrop in the Piedmont of the southeastern United States are approximately 300-350 million years old. These outcrops were formed by the intrusion of molten granite into preexisting country rock at a depth of about ten miles below the surface. Over millions of years, erosion removed thousands of feet of overlying rock, exposing the more resistant bodies of granite.

Granitic outcrops vary tremendously in size, shape, and position in the landscape. Some consist of small, flat-lying exposures (or flatrocks) only a few square feet in area. At the other extreme, Stone Mountain is a steeply sloping outcrop that covers nearly 600 acres and rises approximately 825 feet above the surrounding countryside.

Granite itself is usually very heterogeneous in its mineral composition and texture. Often neighboring outcrops that would appear to have developed as parts of the same rock actually occur on distinctly different types of rock intrusions. For example, Stone Mountain, Panola Mountain, and Arabia Mountain all occur within about fifteen miles of each other, east and southeast of Atlanta. Yet each represents a distinct and separate type of granite: Stone Mountain granite, Panola granite, and Arabia Mountain gneiss, respectively.

The mineral composition and texture of various rock units may have their greatest significance as evidence of weathering patterns that produce distinctive rock outcrop habitats. The rock surface is commonly subject to exfoliation, with “shells” of rock sloughing away to create crevices and talus piles at the base. Uneven weathering of the rock surface results in shallow depressions, called weathering or solution pits. It is in these depressions that the most distinctive granite-outcrop plants and animals occur.

Rock-rimmed pits that are deep enough to hold rainwater harbor a number of rare aquatic plants. Other depressions, which have accumulated a thin layer of soil and which lack a complete rim to retain water, support many unusual annual plants. Other distinctive habitats on the outcrops include deeper accumulations of soil over bare granite, seepage areas created by the slow discharge of water from patches of forest on the rocks, and the edges of nearby forests.

An unexpectedly large number of plant species occur only on Piedmont granite outcrops, which would seem to reflect their antiquity and isolation. Among others, this group includes the monospecific genera Diamorpha and Amphianthus.

Environmental Conditions

Environmental conditions on granite outcrops are harsh and differ sharply from conditions in the adjacent forest. Temperatures on the outcrops typically are much higher than in the surrounding forest because of the high absorption of heat by the rocks and low evapotranspiration. Temperatures in excess of 120 degrees Fahrenheit are common at rock surfaces during the summer months.

Stone Mountain

Image from Darryl Pierce

Shallow mineral soil overlying impervious rock and sparse vegetation cover lead to extraordinarily high water runoff. It has been estimated that more than 95 percent of the annual precipitation in outcrop communities is lost as direct runoff. These conditions make the granite outcrops, despite their occurrence in a region that receives forty-five to fifty inches of rain per year, like islands of desert embedded in a sea of deciduous forest.

Conservation Status

Unfortunately, local landowners and government agencies alike have viewed most of the granite outcrops in Georgia as relatively worthless land, since such property cannot be used for construction, agriculture, or grazing. Thus, outcrops have frequently been used as dump sites for household or construction waste. Many others have been destroyed by quarrying or have been covered by lake waters after the construction of a dam.

Panola Granite

Photograph by Chad A. S. Mullikin

Some sites, however, have been protected, either because of their inaccessibility to humans or because of timely action on the part of governmental or private agencies. These sites include Stone Mountain in DeKalb County, Heggie’s Rock in Columbia County, Davidson-Arabia Mountain Park in DeKalb County, Little Kennesaw Mountain in Cobb County, and Panola Mountain State Conservation Park, which spans Rockdale, Henry, and DeKalb counties.

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Erosion Weathering Deposition Card Sort 

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Erosion Weathering Deposition Card Sort 

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What Are They?

Barrier islands are among the most beautiful and precious features of our coastline. A barrier island is defined as a long, offshore, dune-covered deposit of sand lying roughly parallel to and separated from the mainland by a shallow sound (lagoon) and/or salt marsh; barrier islands are separated from each other by tidal inlets. Our present barrier islands have evolved over thousands of years and are a wonderful example of a delicate but balanced system in a constantly changing environment.

Thirteen percent of the world's coastlines and more than one-third (33%) of the coast of North America is bordered by barrier islands. Along the Atlantic coast alone there are more than 300 barrier islands and spits (a spit is similar to a barrier island but is smaller and attached to the mainland) extending along the coasts of 18 states from Maine to Texas. Each barrier island is different and unique in its own way and although no two are exactly alike, they may have many similarities.

A typical mature barrier island consists of several distinct features or habitats including the ocean, beach, berm, primary dunes, secondary dunes, interdune meadows, shrub zone, maritime climax forest, salt marsh, tidal (or mud) flats and sounds. Many barrier islands also have freshwater sloughs that form in low areas and between old dune ridges. Each habitat, although existing in close proximity to the others, has its own unique characteristics.

Importance of Barrier Islands

Barrier islands are called "barrier islands" because they create a barrier between the mainland and the ocean. They shelter and protect the mainland from the powerful forces of wind, waves, tides, currents and the ravages of storms and hurricanes. They shelter the estuaries that form behind the barriers. Between 75% and 95% of all marine species are dependent upon these estuaries at some point in their lives. They allow marshes to build up in the quiet waters of the sound. The marshes filter the pollutants that come in from mainland rivers and when the marsh grasses die they create detritus, a valuable food source for small marine organisms.

Barrier islands provide valuable habitats for mammals, shellfish and fish including many endangered species, and offer a greater variety of bird species than any other ecosystem in the continental United States. They also serve aesthetic purposes and for years, have inspired artists, poets, writers, bird watchers, boaters, picnickers, sunbathers and swimmers.

Barrier islands are truly a most valuable resource. It is remarkable that although they constantly change and may become badly eroded (some even disappear entirely), they can rebuild if left alone.

Barrier Island Geology and Formation

There are several theories as to how barrier islands form. Georgia's barrier islands are thought to have formed as the result of world-wide sea level fluctuations caused by alternating periods of warm and cold during the Pleistocene Epoch that allowed great continental ice sheets to advance and retreat over the Northern Hemisphere. During glacial advances, huge amounts of water were locked in glaciers causing the sea level to fall. Then, during interglacial periods when it was warmer, the ice melted, causing sea level to rise.

Georgia was never covered by glaciers but it was affected by the rising and falling of the sea level about 40 million years ago. During the Pleistocene, in warm periods, sea level may have been as much as 50 to 100 feet higher than today with the ancient coastline lying along a sand ridge known as Trail Ridge. During times of extreme cold, the shoreline lay as much as 80 miles seaward of its current position.

One theory suggests that Georgia's present barrier islands may have formed during several consecutive periods of glacial melting. The older islands formed thousands of years ago when sea level rose flooding the coastline. (Dates for their formation are unclear and could have been any where from 25,000 to 100,000 years ago.) Ridges of sand dunes were left above sea level and gradually built into barrier islands. Over the next few thousand years sediments from rivers added material to fill in the area between these new islands and the mainland producing mud in which the vast expanses of salt marsh formed. As sea level stabilized these small remnants of old sand dunes gradually built into our older barrier islands. About 11,000 years ago near the end of the Pleistocene, sea level rose again, flooding the coastline to its present location. About 5,000 years ago the rise in sea level slowed to about four to six inches per century, allowing the formation and growth of our newer Holocene islands. Over the last few thousand years sediments from rivers and the islands' natural landward migration have filled in or partially filled in the area between these older and younger sets of islands. Today sea level is rising a little more than one foot per century.

Each period of ice formation and melting created a new sequence of barrier islands along the coast of Georgia. The oldest series of islands, the Wicomico Shoreline, formed when sea level was as much as 95 to 100 feet higher than it is today and is responsible in part for the creation of the Okefenokee Swamp. The next series of barrier islands, called the Penholoway Shoreline formed when sea level was 70 to 75 feet above its present level. The Talbot shoreline formed when sea level was 40 to 45 feet higher; the Pamlico shoreline formed when sea level was 25 feet higher. The Princess Anne shoreline formed when sea level was 15 feet higher, the Silver Bluff shoreline formed when sea level was 5 feet higher.

Courtesy of the Sapelo Island National Estuarine Research Reserve
www.sapelonerr.org
Written by Margaret Olsen

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What Are They? Barrier islands are among the most beautiful and precious features of our coastline. A barrier island is defined as a long, offshore, dune-covered deposit of sand lying roughly parallel to and separated from the mainland by a shallow sound (lagoon) and/or salt marsh; barrier islands are separated from each other by tidal inlets.

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Barrier islands form as waves repeatedly deposit sediment parallel to the shoreline. As wind and waves shift according to weather patterns and local geographic features, these islands constantly move, erode, and grow. They can even disappear entirely.

They are generally separated from the mainland by tidal creeks, bays, and lagoons. Beaches and sand dune systems form on the side of the island facing the ocean; the side facing the shore often contains marshes, tidal flats, and maritime forests. These areas are important habitat for seabirds, fish and shellfish, and nesting sea turtles.

Many barrier islands are found off the U.S. Gulf and East coasts, such as the Outer Banks off North Carolina. Barrier island chains tend to form near river deltas and in areas with low tectonic activity and relatively flat coastal terrain. The rocky cliffs and shifting tectonic plates off the West Coast, along with other features of the terrain and tides, prevent barrier islands from forming there.

These islands are critical to protecting coastal communities and ecosystems from extreme weather. Beach dunes and grasses on barrier islands absorb wave energy before the wave hits the mainland. This generally means smaller storm surge and less flooding on the coast.

Unfortunately, barrier islands are disappearing at an alarming rate. Erosion can be caused by human activities such as ship traffic, hard levees, and infrastructure projects, even those far upriver. Damming and dredging projects can significantly affect the amount of sand and sediment available to fortify barrier islands. The effects of climate change, including rapid sea level rise and extreme weather events, can cause or worsen barrier island erosion.

NOAA supports natural and nature-based infrastructure projects that restore and protect barrier islands and the benefits they provide to coastal communities and ecosystems. Thousands of acres of barrier islands and marshland have been restored or enhanced as part of Gulf Spill Restoration projects. These projects address damage to natural resources and wildlife from the Deepwater Horizon oil spill, but the restored barrier islands also provide added coastal resilience and protect important estuary habitats.

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national estuarine research reserve system

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national oceanic and atmospheric administration

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Barrier islands form as waves repeatedly deposit sediment parallel to the shoreline. As wind and waves shift according to weather patterns and local geographic features, these islands constantly move, erode, and grow. They can even disappear entirely. They are generally separated from the mainland by tidal creeks, bays, and lagoons.

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Georgia Science Teachers Association - GSE Phenomena

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communications@georgiascienceteacher.org if you have any questions about this resource.

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Quick Look

Grade Level: 5 (5-7)

Time Required: 1 hours 30 minutes

(can be split into two 45-minute sessions)

Expendable Cost/Group: US $5.00

Group Size: 1

Activity Dependency: None

Subject Areas: Earth and Space, Science and Technology

NGSS Performance Expectations:

Students learn about water erosion through an experimental process in which small-scale buildings are placed along a simulated riverbank to experience a range of flooding conditions. They learn how soil conditions are important to the stability or failure of civil engineering projects and how a river's turns and bends (curvature, sinuosity) make a difference in the likelihood of erosion. They make model buildings either with a 3D printer or with LEGO® pieces and then see how their designs and riverbank placements are impacted by slow (laminar) and fast (turbulent) water flow over the soil. Students make predictions, observations and conclusions about the stability of their model houses, and develop ideas for how to mitigate damage in civil engineering projects.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Learning Objectives

After completing this activity, students should be able to:

Explain the water erosion phenomenon.

Identify the main causes of erosion along riversides.

Compare the effects of fast (turbulent) flow versus slow (laminar) flow.

Identify solutions that engineers design to mitigate water erosion.

Educational Standards
Suggest an alignment not listed above

Materials List

This activity was designed for classrooms with access to a 3D-printer and an erosion table. However, if either tool is unavailable, instructions are provided for alternative materials.

The class needs:

simulation of river flow, via an erosion table with hydraulic bench OR a stream table OR a homemade erosion table; see below for details on these options

small-size model buildings, one per student, made via 3D printer (plus computer and free drawing software) OR LEGO pieces; see below for details on these options

10 pounds fine sand ($5)

water, sink and buckets

Erosion in Rivers Pre-Activity Quiz, one per student

Erosion in Rivers Post-Activity Quiz, one per student

River Simulation Options

Figure 1. An erosion table filled with fine sand.

1. Erosion table with hydraulic bench for academic purposes, such as the Hydro-Geology Stream table - Hubbard (product #Z06394M) for $1,330 from Nasco at https://www.enasco.com/p/Z06394M; the recommended table dimensions are 26-in wide x 66-in long x 6-in deep; the author performed the activity using this erosion table, shown in Figure 1.

2. Alternatively, use a stream table, such as the Stream Table Kit (product #SB01704M) for $80 at Nasco at https://www.enasco.com/p/SB01704M; its heavy plastic tray is 14-in wide x 48-in long x 3-in deep with a drain hole.

3. Alternatively, create a homemade erosion table; although a bit more work, it is an efficient low-cost alternative that can be created for ~$41 using the following supplies:

a large plastic box of similar dimensions to the erosion and stream tables; manually create a drain (hole) on one end; estimated cost $12

bucket or pan, to collect the water; estimated cost $5

filter, such as a piece of cheesecloth, to keep soil from escaping the pan; estimated cost $4

a pump, with velocity or flow meter if possible, so students can observe differences in erosion effects due to flow rate changes; estimated cost $20

Model Buildings Options

Figure 2. An example 3D printer, the MakerBot Replicator 2.

3D printer, for example, the many models made by MakerBot Industries such as the MakerBot Replicator 2 (Figure 2; $2,000) or MakerBot Replicator Mini Compact ($1,375) at https://store.makerbot.com/; the author used an earlier version of these 3D printers, the Thing-o-matic by Makerbot (http://www.makerbot.com/support/thingomatic/); using any 3D printer also requires the use of computers and software, such as:

computer, one per student; alternatively, small groups of up to three students could work together on one computer so fewer computers are needed

3D modeling drawing application, for designing building units, such as Google Sketch Up (www.sketchup.com; free) or 3D Tin (www.3dtin.com; free); helpful tips, tutorials and download information are available at http://makezine.com/2013/03/28/free-alternatives-to-tinkercad/

For design ideas and downloadable designs, use http://www.thingiverse.com/; suggested designs include http://www.thingiverse.com/thing:151430 and http://www.thingiverse.com/thing:150956

a supply of the filament material the 3D printer uses to make the building models

Figure 3. Using the same LEGO pieces, students create their own model buildings.

Alternatively, give each student an identical set of 20-25 LEGO pieces (estimated cost $3), from which they can make their own unique model buildings (Figure 3); available for purchase at http://shop.lego.com/en-US/Pick-A-Brick-ByTheme;%20http://creative.lego.com/en-us/default.aspx; a suggested mix of typical LEGO pieces for a set of 19 includes the following pieces:

(2) 2 x 6 (one thickness)

(2) 4 x 8 (one thickness)

(2) 2 x 8 (one thickness)

(4) 2 x 3 (double thickness)

(1) 2 x 6 (double thickness)

(4) 1 x 8 (double thickness)

(4) 2 x 8 (double thickness)

Worksheets and Attachments
Visit [www.teachengineering.org/activities/view/nyu_erosion_activity1] to print or download.

Pre-Req Knowledge

The teacher must have a basic knowledge of the water and rock cycles, erosion in rivers and weathering, as well as soils and rocks.

Introduction/Motivation

What is a civil engineer? (Listen to student ideas.) Civil engineers are the people in your community who design projects such as highways, bridges, tunnels, dams, skyscrapers and the many buildings that we rely upon in our communities. They make sure that these projects do what we want them to do and are safe. Some of these civil engineers specialize in certain areas, such as structural, geotechnical, environmental, water and traffic engineers-but they are all considered civil engineers. These engineers play many roles in the design, maintenance and improvement of urban areas. For example, structural engineers design bridges, factories, apartment buildings, retaining walls and other buildings and structures. Water resource engineers design ways to move clean water and waste water around cities and regions by creating dams, reservoirs, treatment plants, piping systems and canals, while environmental engineers make sure that the water is safe for humans and the environment. Transportation engineers plan the systems behind our road, railway, shipping and airplane transport systems. Geotechnical engineers study the mechanical behavior of earth materials, including soil, rock and groundwater.

Soils may seem simple, but in fact they can vary greatly. Engineers analyze the many characteristics and properties of soils. How soils behave is influenced by the physical material that makes up the soil as well as weather and climate. The physical content of soil changes over time, and the soil profile (what is present in the soil) of a specific area of ground can reveal a lot of information about a geographical location. Over time, different events cause soil to change in a variety of ways. For example, if some pollution (contamination) occurred in a particular area and left a residue of some kind, the soil profile would reveal this.

What kinds of soil types can you think of? (Listen to student ideas.) In general, engineers consider four types of soil: clay, silt, sand and gravel/rock. Clay and silt are very small pieces of soil. Sand particles are bigger than clay and silt, and rock is the biggest. Major climatic events can also impact the development and properties of soil-events such as hurricanes, blizzards and droughts can greatly contribute to the properties of soil.

Have you ever heard of the word " erosion" before? (Write "erosion" on the classroom board.) What is erosion? Erosion is the process of wearing away the surface of the Earth in different ways. Erosion can happen in many, many forms (water, waves, wind, glacier, chemical, temperature). One of the most common ways that soil erodes is by water. Have you seen small clods of sand being washed out or moved around by water? This happens because of water erosion. Since erosion moves soils and rocks from one place to another, it continually changes the surface of the Earth. The Grand Canyon was formed due to water erosion over many, many years! This is impressive, because compared to other material that make up the Earth, gravel and rock are the most difficult to erode.

In rivers, the erosion phenomenon also changes the edges of riverbanks, as water energetically acts against the soils. The movement, or flow, of water in rivers is not always the same; the speed of water changes depending on the location in the river. For example, when water goes around a turn in a river, the water on the inside of the turn moves faster than the water on the outside of the river. When water moves fast, it is called turbulent flow; when water moves slowly, it is called laminar flow. So, the path of a river, specifically how many turns it has, can change how the water moves through it, which causes erosion.

Figure 4. As applied to a river, sinuosity is defined as the path a river takes compared to the shortest possible path that could be taken.

How many turns, and what they look like, in a river, is called curvature. The magnitude, which is the size of the curves, or turns, in a river tells engineers how likely erosion is to occur, or how susceptible the river is to erosion. Engineers use the term sinuosity or sinuosity index to describe the shape of a river; it is defined as the path the river takes compared to the shortest possible path that can be taken. For example, a very curvy river has a higher sinuosity then a straight river. (Draw Figure 4 on the classroom board.) This top graphic describes a river with high sinuosity, the middle one describes a river with a medium sinuosity, and the bottom graphic describes a completely straight river with a sinuosity of 1.

As water travels over the land, it takes some soil with it and leaves or deposits some along the path it takes; this is called deposition. Because water moves some of the soil, through the process of erosion, any buildings or structures on top or nearby that river and its surrounding soil can be affected. In the same way a sand castle on the beach needs a certain amount of wet and dry sand to stand tall and strong, real buildings need a certain blend of soil below them to stand strong, tall and unmoving; this is called stability.

Because of ongoing erosion in the environment and the lack of knowledge by some builders, sometimes a loss of stability occurs, which can lead to the collapse, or failure, of structures. The "failure of structures" is defined in many ways by engineers. In general, failure means that the building does not meet certain standards, or requirements, put in place by a governmental agency. These standards describe allowable movement of structures. Some buildings that are considered to be stable today may be at risk because the erosion taking place in a certain river is threatening their stability. Engineers study erosion so that they can protect the environment, structures, landmarks and people's lives. They design solutions to prevent damage to structures and keep people safe. Civil engineers are responsible for designing buildings that are stable; geotechnical engineers are responsible for making sure the soil underneath buildings is stable.

Soil erosion occurs naturally, but is also the result of land changes caused by people. In fact, soil can be structurally reinforced using a variety of materials and design methods, similar to how concrete is reinforced using steel rebar. Foundation stability of structures is important in order reduce the risk of failure. If engineers do not take erosion into account when designing structures, many failures, or near failures, can occur. Major climatic events can also cause the surface of the Earth to erode, breaking down rocks and depositing sediment in new locations. Unlike common weather events, these major events can affect the surface of the Earth dramatically. Engineers are responsible to ensure that even if a major climatic event occurs, the erosion will not damage the surrounding structures. The changing cycles of natural disasters and hurricanes call for engineers to come up with new, innovative ideas to mitigate the disaster risks. What are some new, innovative ideas that you can come up with to help people prepare for hurricanes or floods?

Procedure

Simulation and Fabrication Tools

An erosion table and hydraulic bench system provide a way to simulate river and/or flood water flowing through an enclosed soil site so that the relationship between water velocity and soil erosion can be easily investigated. A classroom erosion table enables students to visualize the effects that a river or stream can have on surrounding soil, which affects surrounding structures.

Google Sketch Up and 3D Tin are two online applications that can be used for three-dimensional (3D) design for use in 3D printers. These simple programs enable students to imagine and design prototypes of real objects through easy-to-use tools. The web interfaces are very natural and the mix of colors plus the solid building block modeling system makes for a fun way to quickly replicate designs. This aspect of the activity enables each student to express his or her imagination and take ownership of the experiment.

Before the Activity

From the options presented in the Materials List section, decide what you will use for the river erosion simulation and model buildings. As necessary, briefly research and explore the 3D modeling program options.

If 3D-printed buildings are being used, set aside a separate time to have students design and print the small-scale buildings so they are ready to use when starting this activity.

(optional) Prepare introductory lessons about the rock cycle and water cycle to provide context for this activity and help students visualize and participate in the way the cycles work. See some suggested resources in the Additional Multimedia Support section.

(optional) Assemble a few photographic images to help incite discussions about soil erosion, such as images of collapsed structures due to erosion caused by the river layout. Use search terms such as: soil erosion, river erosion, collapsed structures, riverbank collapse. See some suggested images in the Additional Multimedia Support section.

Gather materials and make copies of the Erosion in Rivers Pre-Quiz and Erosion in Rivers Post-Quiz, one each per student.

Prepare the erosion table (or stream table or homemade erosion system) with a variable path. Make the river have some tight curves, some wide curves and some straight paths, in order to expose students to different river scenarios.

With the Students

1. Teach students about erosion, including the information provided in the Introduction/Motivation section. Explain new vocabulary terms.

2. Challenge students to brainstorm ideas to mitigate disasters caused by erosion. Discuss their predictions and remediation solutions. Record important input by students on the classroom board.

Figure 5. Students place their model buildings along the riversides, at locations where they predict they will be stable and safe from erosion.

3. Administer the pre-quiz and have students complete them independently.

4. Give students their already-made 3D-printed model buildings, or have students design and construct LEGO buildings with sets of LEGO pieces you provide.

5. Then move to the erosion table and ask each student to predict where on the riverbank s/he wants to place his/her model building so that it provides a nice river view but is also safe from erosion. The goal is for their structures not to move due to water erosion. Then have students place their buildings along the river (Figure 5).

6. Once every student has made a prediction and placed his/her building, open the hydraulic bench pump at a low flow rate to allow water to run under laminar flow (slow, steady, constant). Remind students that laminar flow is slow-moving water. Expect a few buildings to collapse due to soil erosion, while most survive. (Note: For this activity, a building collapse means that it moves a noticeable amount, including falling over, tilting or moving downstream.)

7. Once the effects of the laminar flow are established, incrementally increase the flow rate in order to simulate large storms and turbulent flow (fast, rapid, erratic). Remind students that turbulent flow is fast-moving water.

Figure 6. Students observe their buildings' performances during the modeling of turbulent flow.

8. As the flow rate is increased, make sure students observe the increase in the rate of erosion and encourage them to pay special attention to the locations they selected-areas where they believe no damage will occur. Expect the simulation of heavy storms and turbulent flow to result in the failure of many buildings, as shown in Figure 6.

9. Once the results of the erosion due to turbulent flow are clear, lead a class discussion. Refer to the Assessment section for suggested questions and topics.

10. Conclude by administering the post-quiz, having students independently complete them.

Vocabulary/Definitions

civil engineer: A person who uses his/her understanding of science and math to design, build and maintain projects such as roads, highways, bridges, canals, dams, tunnels, skyscrapers and other buildings that we rely upon in our communities.

curvature: How many turns a river takes and what size they are.

deposition: The process of leaving small pieces of soil behind after water erodes land.

erosion: The wearing away of the surface of the Earth by natural processes such as wind or moving water.

geology: The scientific study of the Earth, how it is formed, and how it changes over time.

geotechnical engineering: A branch of civil engineering that studies the way Earth behaves (mechanical behavior of earth materials), including soil, rock and underground water (groundwater).

laminar flow: Slow, steady, constant flow of water.

magnitude : The size of something; how big or small something is.

rock: A solid material made of one or more minerals; stone.

sinuosity: A number used to describe the curvature of the path a river takes, compared to the shortest possible path that can be taken.

soil: A natural resource made of broken-down pieces of living and non-living earth materials. Can change form through the rock and water cycles. Three phases of matter occur in soil: solids, water and air. Also called dirt.

stability : The ability of a building to stand strong over time, especially after erosion occurs.

susceptibility: The chance that something will be damaged or harmed.

turbulent flow: Fast, rapid, erratic or chaotic flow of water.

velocity: How far you go in a certain amount of time (distance traveled per time taken); speed.

water erosion: The movement of soil due to moving or flowing water. Also known as valley erosion, stream erosion or gully erosion.

Assessment

Pre-Activity Assessment

Pre-Quiz: Administer the Erosion in Rivers Pre-Quiz. Review students' answers to learn their baseline understanding of erosion. A space is provided for students to draw in their building locations before flooding, which helps them predict where to put their buildings on the erosion table.

Activity Embedded Assessment

Questions: During the activity, while students are considering building placement, ask questions such as:

Why not place your building in the middle of the river? (Answer: It would collapse inmediately! Also, water bodies are state property, and no construction is permitted to be placed on them.)

Do you think the design of your building can affect how erosion acts on it? (Answer: Yes! Stable structures resist erosion much better.)

Post-Activity Assessment

Concluding Discussion: After completing the activity, informally assess students through in-class questions to determine the impact of the activity on their learning.

Ask students to share their observations and describe how their model buildings performed.

Ask students to relate the performance results to where their buildings were located with respect to the river shape and curvature.

Ask other questions to elicit whether students understand the concept of erosion in rivers, the need to design and build appropriate structures in the right locations, and the role of civil engineers in ensuring peoples' safety while designing new structures.

Review the answers to the pre-quiz.

Ask the Investigating Questions.

Post-Quiz: At activity end, administer the Erosion in Rivers Post- Quiz to assess students' understanding of erosion. Review their answers to gauge their comprehension and get their feedback from the activity.

Investigating Questions

What is water erosion? (Answer: It is the process by which soil is removed from the Earth due to water impact, and then transported and deposited in other locations downstream.)

Does the river sinuosity or curvature affect the erosion in the riversides? (Answer: Yes! The more curve of the river, the more loss of soil when water impacts the riverside.)

How can you avoid building damage due to water erosion? (Example answers: Do not build in areas susceptible to erosion. Prior to construction, completely understand the specific geology of the surrounding area and soils in order to predict any erosion phenomena that might occur; this helps engineers decide exactly where to locate new buildings as well as any design or structural steps to make the building more stable at that location. Choose construction materials that resist water erosion. Provided adequate foundation systems anchored to bedrock. Install vegetation to help the soil resist erosion. Modify the water flow or direction.)

Activity Scaling

For lower grades, use less technical vocabulary and modify the Introduction/Modification content to present the activity in a simpler fashion. Instead of designing and printing 3D buildings, use LEGO pieces to make this activity more accessible to younger students. Have students work in groups. Have them create a checklist of the steps they need to follow in the activity and a list of what they observe.

For higher grades, have students do Internet searches for more in-depth information on erosion. Have them draw their predictions of what will happen when water flows down the erosion table. Also have them make predictions for different patterns of river flow.

Additional Multimedia Support

Resources for introductory lessons and activities about the rock cycle and water cycle:

Rock Cycle curricular unit

Earth Rocks! lesson

Ride the Rock Cycle lesson at http://209.7.198.36/geologyonline/lessons/6.4/lesson.pdf

Fresh or Salty? lesson

Where Has All the Water Gone? lesson

Water Cycle Game at http://www.nps.gov/wica/forteachers/upload/Hydrology-Water_Cycle_Game-2.pdf

U.S. EPA water cycle interactive games and activities at http://water.epa.gov/learn/kids/drinkingwater/gamesandactivies.cfm

Example soil erosion images to show students:

http://www.cambodiadaily.com/archives/three-missing-after-mekong-riverbank-collapse-in-kandal-52710/

http://commons.wikimedia.org/wiki/File:River_Erosion_-_geograph.org.uk_-_358650.jpg

http://assets.knowledge.allianz.com/img/natural_disasters_dangerous_building_eroding_cliffs_landslide_q_49122.jpg

http://www.vanguardngr.com/2012/06/erosion-anibeze-community-cries-out-for-help/

http://en.wikipedia.org/wiki/File:River_erosion_near_Arncliffe,_Littondale,_Yorkshire_Dales_-_geograph.org.uk_-_40749.jpg

http://upload.wikimedia.org/wikipedia/commons/b/b0/Dead_Sea_Coastal_Erosion_March_2012.JPG

http://www.masterbuilder.co.in/wp-content/uploads/2013/06/212.png

http://www.epa.gov/climatechange/images/impacts-adaptation/GroundCollapsing.jp

http://www.nmdirtbags.com/images/coast_highway.jpg

http://archives.thestar.com.my/archives/2006/11/29/nation/temple.jpg

Cartoons and comics http://www.cartoonstock.com/directory/e/eroded.asp

Copyright © 2014 by Regents of the University of Colorado; original © 2012 Polytechnic Institute of New York University

Contributors Sophia Mercurio, Eduardo Suescun

Supporting Program AMPS GK-12 Program, Polytechnic Institute of New York University

Acknowledgements

This activity was developed by the Applying Mechatronics to Promote Science (AMPS) Program funded by National Science Foundation GK-12 grant no. 0741714. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: June 19, 2019

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Students learn about water erosion through an experimental process in which small-scale buildings are placed along a simulated riverbank to experience a range of flooding conditions. They learn how soil conditions are important to the stability or failure of civil engineering projects and how a river's turns and bends (curvature, sinuosity) make a difference in the likelihood of erosion.

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Yellowstone National Park (U.S. National Park Service)

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On March 1, 1872, Yellowstone became the first national park for all to enjoy the unique hydrothermal and geologic features. Within Yellowstone’s 2.2 million acres, visitors have unparalleled opportunities to observe wildlife in an intact ecosystem, explore geothermal areas that contain about half the world’s active geysers, and view geologic wonders like the Grand Canyon of the Yellowstone River.

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Quick Look

Grade Level: 3 (3-5)

Time Required: 15 minutes

Lesson Dependency: None

Subject Areas: Earth and Space

NGSS Performance Expectations:

Summary Students are introduced to the primary types of erosion-chemical, water, wind, glacier and temperature. Students investigate examples of each erosion type and discuss how erosion changes the surface of the Earth. Students also learn why engineers need to be aware of the different types of erosion in order to protect structures and landmarks from the damaging effects erosion can cause.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

Civil engineers must carefully study the surrounding environment and soil composition to safely design and build any sort of structure on a piece of property. Buildings, roads and bridges require solid foundations and preferably land that is not prone to erosion (such as flood plains). Engineers also employ materials that resist erosion, such as water-proof materials or materials impervious to acid rain. Environmental engineers design surrounding landscaping to include trees and other vegetation in order to help prevent wind and water erosion since roots make soil more stable and less exposed to weathering forces. Engineers also design roads and sidewalks so that they may expand and contract with temperature changes without endangering the integrity of the structure, such as sidewalk "control joints" to control cracking.

Learning Objectives

After this lesson, students should be able to:

List several different types of erosion.

Describe several land formations that have been created by erosion.

Explain how engineers learn about erosion to design or protect structures.

Educational Standards

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All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

Click to view other curriculum aligned to this Performance Expectation

This lesson focuses on the following Three Dimensional Learning aspects of NGSS:

Science & Engineering Practices

Disciplinary Core Ideas

Crosscutting Concepts

Make observations and/or measurements to produce data to serve as the basis for evidence for an explanation of a phenomenon.

Rainfall helps to shape the land and affects the types of living things found in a region. Water, ice, wind, living organisms, and gravity break rocks, soils, and sediments into smaller particles and move them around. Living things affect the physical characteristics of their regions.

Cause and effect relationships are routinely identified, tested, and used to explain change.

Suggest an alignment not listed above

Introduction/Motivation

Have you ever wondered why the surface of the Earth looks the way it does today? Does it look the same as it did 100 years ago? The Earth's landscape is continually being shaped and modified by the forces of nature. Wind, ice, water and temperature have all had a hand in making the Earth look the way it does today. These processes are called erosion, which is the wearing away of the Earth by natural processes. Several different types of erosion exist: chemical, water, wind, glacier and temperature. (List them on the board.) We are going to learn more about them today.

Chemical erosion is a reaction that usually involves acid rain. Acid rain is rain that has been polluted by chemicals in the air. These chemicals change the pH of the rainwater and can be harmful to streams, lakes, forests and the animals living in them. Acid rain can also be harmful to buildings and decorative statues by breaking down the materials from which the structures are made. If you have ever visited Mammoth Cave in Kentucky or Carlsbad Cavern in New Mexico, then you have seen the effects of chemical erosion. Both of these caves were carved out of solid land by chemical reactions! Engineers are working on acid rain and chemical erosion by creating cleaner burning fuels and machines (such as cars) that release less pollution into the air. Students can conduct their own engineering investigation of chemical erosion with The Effects of Acid Rain activity.

Water erosion is perhaps the most familiar type of erosion. Have you ever watched the moving water in a river or stream pull bits of the bank along with it? When water from rivers, streams or rain storms breaks away at bits (or larger chunks) of land while moving over it, that is considered water erosion. Water can wash away valuable nutrients from farmland, but is also responsible for shaping the Grand Canyon in Arizona and Rainbow Bridge in Utah. Engineers attempt to reduce water erosion by directing the flow of water with dams and levees. They also design technologies to measure scouring, which is the water erosion of a stream bed around the supports for a bridge, which has caused many bridges to collapse in the past.

Wind erosion happens when wind blows away the top layer of soil or sand. Some of the tiny particles of sand that are carried away by the wind act like sandpaper, wearing down larger objects as they pass. Wind erosion can create and move entire sand dunes, shape rocks and other structures, and cause dust storms. The Dust Bowl of the 1930s is a good example of the damage wind erosion can cause. Engineers develop technologies that help to reduce the effects of wind erosion for farmers.

Glacier erosion is not as common as other types of erosion. A glacier is created by fallen snow that has been pressed into large areas of hard ice on land. These glaciers are slowly pulled downhill by gravity, and wear away at the Earth's surface as they move. Have you ever ridden on the Matterhorn at Disneyland? The original Matterhorn is a mountain in Europe that was formed by glacier (ice) erosion. Glacier erosion has caused many large rock formations on Earth, such as Yosemite Falls in California and the Grand Tetons in Wyoming.

Have you ever noticed that sidewalks are not continuous sheets of concrete? They have grooves or cuts in them that we often call "cracks" in the sidewalk. Why are they there? These grooves are called "control joints" and they are intentionally designed to help prevent the sidewalk from cracking too much by giving it room to grow and shrink as the weather fluctuates between hot and cold. This is called temperature erosion. Temperature erosion can cause metals or concrete to break, such as roads and bridges.

Engineers must learn about and understand erosion in order to safely design and build structures for people to use and visit. Engineers also learn about erosion to help protect existing land formations and monuments that document our world's history. Civil engineers use their knowledge of erosion to design buildings, roads and bridges in areas that might not have a lot of natural erosion or by using sturdy materials that resist erosion. Environmental engineers plant trees and other vegetation in order to help prevent wind and water erosion from damaging land. Plant and tree roots limit erosion by helping to hold the soil in place. Engineers also design highways, overpasses and sidewalks in a way that allows the materials to expand and contract with temperature changes so that they will not crack too much, and thus remain strong and safe for their users. Refer to the Glaciers, Water and Wind, Oh My! activity to have students further investigate different types of erosion.

Lesson Background and Concepts for Teachers

Erosion is the wearing away of the surface of the Earth by natural processes (weathering, dissolution, abrasion, corrosion, etc.). Chemical, water, wind, glacier and temperature are continually changing the landscape of the Earth.

Chemical Erosion

Chemical erosion involves a chemical reaction (one or more substances changes into others). Most chemical erosion is the result of acid rain. Acid rain occurs when rain mixes with elements and gasses in the air, specifically pollutants like sulfur oxides and nitrogen oxides. These pollutants come from vehicles, factories and power-generation plants that burn fossil fuels. See Figure 2 for an illustration of the acid rain cycle. This causes the water to have an acidic pH of approximately 5. Note: On the pH scale, 7 is neutral, that is, "pure" water, with any number towards 1 being more acidic, and any number higher than 7 being more basic. Wind carries this contaminated water hundreds of miles away from its original pollution site, which then harms streams, lakes, forests and any water life that resides there (such as frogs and fish, among others). In addition to impacting nature and other creatures, acid rain also destroys human-made structures, such as historical buildings and monuments. Other examples of chemical erosion include Mammoth Cave in Kentucky and Carlsbad Cavern in New Mexico, both carved out by chemical erosion (see Figure 3).

Environmental engineers attempt to neutralize acid rain by planting trees because they can have a buffering effect on acid rain. Forests reduce the acidity through the leaching process on leaves and the ion exchange in the soil. Engineers are also working on decreasing pollution by designing cleaner burning fuels and vehicles that release less pollution into the air. Engineers also try to protect structures from chemical erosion by choosing building materials that are resistant to acid rain

Water Erosion

Water erosion is perhaps the most familiar type of erosion. Water erosion can take many different forms. Sheet erosion is when a fairly uniform layer of topsoil is removed by raindrop splash and run-off during storms. This can cause soil to lose nutrients, which affects the land's ability to produce crops. Rill erosion is caused by runoff water gathering in flow lines (usually on recently cultivated land). It leaves small channels along the soil and often deposits this soil in streams or reservoirs, which can damage the surrounding ecosystem. If rill erosion is not addressed, water continues to deepen these channels into gullies ( gully erosion). Gully erosion results in the loss of significant amounts of land. Tunnel erosion occurs when water removes soil below the Earth's surface. This causes cavities to form underground, which weakens the surface. If these tunnels collapse, they become deep gullies. Tunnel erosion is dangerous because these cavities could collapse at anytime and cannot be detected from above. Stream-bank erosion is caused by moving streams or river water wearing away the surrounding banks. This can drastically change the course of a river and ultimately the surrounding landscape. Shore erosion deposits sediment into the body of water and changes coastline (storms, such as hurricanes, can accelerate this process). Water erosion has also shaped canyons (such as the Grand Canyon in Arizona) and rock formations (such as the Rainbow Bridge in Utah).

Engineers try to minimize erosion by directing the flow of water using dams and levees. Planting grass and trees to form strong root systems or laying out netting can also decrease water erosion. Scouring is the erosion of streambed material that supports bridges and has been the cause of disasters and near-disasters throughout the nation. Engineers have developed several systems to measure scouring, including remote sensors and active sonar that monitors stream scouring as it happens. Figure 4 illustrates different types of water erosion.

Wind Erosion

Wind erosion creates and moves entire sand dunes, shapes rocks and other structures, and causes dust storms. Sand dunes are always being reshaped and shifting due to the wind. Dunes start out as mere ripples in the sand and gradually increase in size. Sand is moved up to the top of the dune until the pile becomes so steep that it collapses and slumps down the other side (the slip face; see Figure 5). Sand dunes are particularly vulnerable to wind erosion because they are completely composed of loose sand without anything anchoring them in place.

Wind erosion also shapes rocks and deteriorates structures, such as the ancient pyramids in Egypt. The wind picks up grainy particles-such as sand-and acts like airborne sandpaper that wears away (sands down) surrounding surfaces. The Devil's Tower rock formation in Wyoming (see Figure 6) was created by wind erosion. It used to be a volcano, but now all that remains is the solidified, lava core. The wind was powerful enough to wear away an entire volcano!

One of the biggest problems associated with wind erosion is dust storms. The wind picks up dust, leaving crops exposed and blocking out the sun with a big black cloud. Farmers protect their crops (particularly potatoes) by planting larger crops (like rye) surrounding them or covering them with straw and foliage. Figure 7 shows unprotected and protected crops.

Glacier Erosion

A glacier is created by fallen snow that has accumulated and been compressed into massive ice formations on land. Glaciers make up about 10% of the world's total land area. These masses are slowly pulled downhill by gravity, eroding the surface of the Earth as they move. Glacier erosion occurs by abrasion, crushing and fracturing material in the path of a glacier. This moving glacier picks up rock and sand along the way causing their surfaces to become extremely rough, which wears away even more material. Glacier erosion shaped Yosemite Falls in California, created the u-shaped valleys in Rocky Mountain National Park in Colorado (see Figure 8), and formed the Grand Tetons in Wyoming. The Matterhorn, a mountain in the European Alps, was also shaped by glacier erosion. It is unique in that it has four faces (slopes) that face the four compass directions.

Temperature Erosion

Temperature erosion causes materials to crack and break apart. When material such as concrete or steel heats up (from the sun, for example), it expands; when it gets cold it shrinks in size. This fluctuation in size due to temperature can cause the material to crack. Colorado is an excellent example of a climate where temperature can be a challenge for materials, since one day it can be 70° and the next day it can snow, and be only 40°.)

Engineers account for these conditions by putting grooves in sidewalks (called control joints, see Figure 9) and expansion joints in bridges. This minimizes the damage caused by thermal erosion, which is important since broken concrete on the roads and walkways can be dangerous.

Associated Activities

Lesson Closure

Can you remember the different types of erosion? (Listen to student responses.) That's right: chemical, wind, water, glacier (ice) and temperature erosion. Wow, that's a lot of ways that nature can change the surface of the Earth. In fact, some of the coolest natural land formations were created by a type of erosion. Can you name some of them? (Listen to student responses.) For example, the Grand Canyon was formed by water erosion, sand dunes are formed by wind erosion, and the Matterhorn, a mountain in the European Alps, was caused by glacier erosion. Erosion is a natural process, but humans have an effect on the amount of erosion that occurs in some areas as well. Can you think of how? Well, by the emissions from our factories and vehicles we pollute the air, which can cause acid rain and chemical erosion. Also, we construct buildings and dams that may alter the natural path of water and wind erosion. Those are just a few ways that humans affect erosion. Engineers must learn about how erosion works in order to help prevent too much of any one type of erosion from occurring. Engineers design and build the schools, skyscrapers and structures where people live and work. They are also involved in protecting existing land formations and monuments that people visit and tht we wish to keep standing and in unaltered shape.

Vocabulary/Definitions

acid rain: Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water.

deposition: The act or process by which an agent of erosion such as wind or water lays down matter (sediment).

erosion: The wearing away of the surface of the Earth by natural processes (weathering, dissolution, abrasion, corrosion, etc.); types of erosion include: chemical, water, wind, glacier and temperature.

geology: The scientific study of the origin, history and structure of the Earth.

glacier: A huge mass of ice slowly flowing over a land mass, formed from compacted snow in an area where snow accumulation exceeds melting.

limestone: A type of sedimentary rock consisting of the mineral calcium carbonate.

scouring: The water erosion of a stream bed around the supports for a bridge; can be the cause of a bridge to collapse.

sediment: Material that settles to the bottom of a liquid.

slip face: The side of a sand dune on which sand collapses once the dune slope becomes too steep to support any more build up of sand.

weathering: Gradual physical and chemical wearing away of rocks.

Assessment

Pre-Lesson Assessment

Discussion Questions: Ask a couple of discussion questions to get students thinking about the upcoming lesson. After soliciting answers, explain that these questions will be answered during the lesson.

What causes the surface of the Earth to look the way it does?

Has the surface of the Earth always looked the same since the beginning of time?

Post-Introduction Assessment

Voting: Ask a true/false question and have students vote by holding thumbs up for true and thumbs down for false. Tally the votes and write the totals on the board. Give the right answer.

True or False: Erosion can wear away the surface of the Earth by chemicals, wind, water, glaciers and temperature (Answer: True)

True or False: Chemical erosion is a reaction that usually involves water that has been polluted by chemicals, such as acid rain. (Answer: True)

True or False: Wind erosion is rivers, streams or even rain, breaking away at bits of land while moving over it. (Answer: False, this description is of water erosion, not wind erosion.)

True or False: Wind erosion can create and move entire sand dunes, shape rocks and other structures and cause dust storms. (Answer: True)

True or False: Engineers do not need to know about erosion. (Answer: False, engineers use their understanding of erosion for many different applications, including the safe design and building of structures, highways, airport landing strips, ski hills, tunnels, bike paths, sidewalks as well as the protection of natural and human-made monuments.)

True or False: Engineers also learn about erosion to help protect existing land formations and monuments that people want to keep around. (Answer: True)

True or False: Water erosion causes sand, acting as airborne sandpaper, to wear away surfaces as it moves over something. (Answer: False, this description is of wind erosion, not water erosion.)

Lesson Summary Assessment

Can You Picture It? Show students pictures of different items that have been affected by erosion and see if they can guess which type of erosion caused it. For example, the Grand Canyon, Carlsbad Caverns, Ayers Rock, the Grand Tetons, Devils' Tower, an eroded statue, pavement cracks, etc.

Idea Web: Ask students to develop a list of the different types of erosion. What effects does erosion have on us and our environment? What are possible solutions for reducing these effects? What can engineers do to help?

Engineering Poster: Using what they learned in the lesson on erosion types, have student teams create posters of their unique designs for protective structures for statues or natural landforms that could withstand one of the erosion types (water, wind, temperature, glacier or chemical). Have them title their posters with a hypothetical engineering firm name (for example, Erosion Engineering & Associates).

Lesson Extension Activities

Find some images of your community and region from 100 years ago to modern day. Have students compare and contrast the images. What has changed? How much of this change is due to natural erosion? How much is due to human intervention (buildings and highways, etc.)? If the area had been left alone except for natural processes such as water, wind and temperature, what parts of the landscape would have changed over 100 years due to erosion?

Have students investigate the human effect on erosion. For example, What are examples of human contributions to acid rain or waterways rerouting that have affected the surrounding landscapes? Have students develop plans to help reduce the human effect on the natural erosion that occurs over time. Have them describe activities that they could participate in that would help with land conservation and preservation of monuments or landscapes.

References

Cavers, Curtis. "Soil Management on Potato Land." Food and Rural Initiatives, Crops, Manitoba Agriculture, Canada. Accessed March 2006. Originally found at http://www.gov.mb.ca/agriculture/crops/potatoes/bda01s30.html

Sidewalk Repair Program, Public Works Department. City of Long Beach, CA. Accessed September 22, 2020. http://longbeach.gov/pw/services/sidewalk-maintenance/

"Investigating Earth's Surfaces." Earth Science Lesson Plans Library: 6-12, Discovery Education. Accessed 2006. Originally found at DiscoverySchool.com

Acid Rain article. Unit 5: The Wonderful Solvent: Water. The Government of the Hong Kong Special Administrative Region of the People's Republic of China, Education and Manpower Bureau, Science Education Section, Science (S1-3). Accessed July 25, 2006. Originally found at http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/en/syllabus/unit5/article-ar.htm

"Erosional Landforms." May 3, 2005. Natural Hazards, National Geophysical Data Center, NOAA Satellite and Information Service. Accessed August 1, 2006. Originally found at http://www.ngdc.noaa.gov/ngdc.html

View All Parks A-Z, Parks and Recreation. National Park Service, U.S. Department of the Interior. Accessed September 22, 2020. http://www.nps.gov/parks.html

"Dunes - Getting Started." January 19, 2004. Coasts: Sand and Dunes, U.S. Geological Survey, U.S. Department of the Interior. Accessed 2006.

"Effects of Acid Rain" May 4, 2020. U.S. Environmental Protection Agency. Accessed September 22, 2020. https://www.epa.gov/acidrain/effects-acid-rain

Erosion. Natural Resource Conservation Service, U.S. Department of Agriculture. Accessed September 22, 2020. https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/landuse/crops/erosion/

Copyright © 2006 by Regents of the University of Colorado.

Contributors Teresa Ellis; Malinda Schaefer Zarske; Janet Yowell

Supporting Program Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: May 27, 2022

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Students are introduced to the primary types of erosion-chemical, water, wind, glacier and temperature. Students investigate examples of each erosion type and discuss how erosion changes the surface of the Earth. Students also learn why engineers need to be aware of the different types of erosion in order to protect structures and landmarks from the damaging effects erosion can cause.

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Ready. Set. Get out and explore the best attractions and places to stay in Georgia, from beaches to small towns and cities. Plan your Georgia vacation today.

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But the story of Georgia's geology is not just about the past. Georgia is rich in such geological resources as marble, granite, and kaolin; production of these resources accounts for a large proportion of Georgia's wealth. In addition, the geological beauties of rock, river, and mountain provide the attractions that annually draw thousands of tourists to Georgia's state parks and other recreational areas.

Running northeast to southwest through the center of the state, the Piedmont and Blue Ridge provinces are composed mainly of igneous rocks (formed by the cooling and crystallization of molten magma) and metamorphic rocks (caused by extremely high temperatures and pressures deep below the earth's surface). In the area around Elberton huge quarries mine world-famous bodies of granite, an igneous rock, while valuable deposits of slate and marble lie within the Piedmont rocks of central Georgia. Piedmont and Blue Ridge rocks not only have undergone intense metamorphism but also show the effects of having been bent, twisted, and contorted by tremendous compressional forces within the earth's crust, not once but many times. Large ancient faults, long inactive, that slice through the Piedmont area offer further evidence of these enormous forces.

Toward the end of the Paleozoic era, North America collided with the ancient continent of Gondwana to form the supercontinent Pangaea. When Pangaea broke apart due to continental drift during the Triassic period, the great Appalachian chain was also torn apart. Today, segments of the old Appalachians are found in northern South America, North America, northwestern Africa, Greenland, Great Britain, and the Scandinavian region of Europe.

To the west of the Cartersville Fault lie the Valley and Ridge province and the Appalachian Plateau. Rocks of these provinces are generally as ancient as those of the Piedmont but have not been subjected to the intense degree of metamorphism that the Piedmont has. For this reason, they still contain their original sedimentary textures, structures, and fossils. The rocks in these areas occur as layers (also called strata) and consist mainly of sandstones, shales, limestones, and dolostones.

Sedimentary rocks originally were deposited in horizontal layers, but in the Valley and Ridge area these layers have been folded and faulted, squeezed and deformed by the same continental collision event that pushed Piedmont metamorphic rocks westward up and over the Valley and Ridge strata along the Cartersville Fault. As a result, the layers are no longer horizontal but are bent into great folds. As these bent and folded layers of rock gradually weather and erode, they form the long winding ridges and valleys from which the province takes its name. Many of these rocks contain abundant fossils and are famous among paleontologists, both professional and amateur. From these fossils and the rocks that contain them, it is clear that most Valley and Ridge strata formed in ancient seas that inundated the interior of North America numerous times during the Paleozoic era. Views of these folded rock layers may be seen in the rock outcroppings along Interstate 75 between Cartersville and Chattanooga, Tennessee, as well as along many state and county roads in the area.

In the Appalachian Plateau, sedimentary layers are largely undeformed and therefore are still horizontal. At lower elevations, these rocks are mainly limestones and dolostones similar to rocks seen in the Valley and Ridge province. Forming the upland areas of the Plateau region, however, are Pennsylvanian-age sandstones, shale, and coal beds that formed along the coastline of an ancient seaway that extended at times from northwest Georgia all the way to Nevada. These rocks are also fossiliferous and contain beautifully preserved fossils of land-dwelling animals and plants that lived in those coastal forests, marshes, and river floodplains. These rock strata may be seen exposed at Lookout Mountain and Sand Mountain, particularly at Cloudland Canyon State Park just east of Trenton.

Looking at Georgia's geologic map, one can see a distinct change in the character of the land on either side of the fall line. The fall line crosses through the center of the state from Augusta in the east through Macon and on to Columbus in the west and marks the place where rivers flowing off the Piedmont and onto the Coastal Plain have prominent waterfalls and rapids (hence the term fall line). Technically, this line runs from Georgia to New York, forming the boundary between the hard, crystalline rocks of the Piedmont and Blue Ridge and the softer, more erodable strata of the Coastal Plain. The rapids and waterfalls that define the fall line are caused by the different characteristics of the rocks on either side. Rivers cannot erode very deeply into the hard rocks of the Piedmont, but they can easily erode the soft strata of the Coastal Plain. Rapids and falls are formed as the erosion of soft strata results in the streams' channels becoming steeper along the fall line.

South of the fall line are sedimentary strata of the Coastal Plain. In most areas of the Coastal Plain, the strata are undeformed and virtually unaltered. Indeed, in some places these ancient sedimentary strata are still soft, looking almost exactly as they did when they were first deposited. These strata contain fossils that clearly show their age, however.

The oldest Coastal Plain strata in the state are of Triassic, Jurassic, and Lower Cretaceous age. They cannot be seen at the surface, though, because they lie deeply buried beneath younger sedimentary layers. Even though they are buried, they can still be studied by an analysis of drill cores taken from them and by such remote-sensing technology as seismic profiling. From these types of studies geologists have learned that Georgia's deeply buried Coastal Plain sediments formed during the time when North America began to break away from the supercontinent, Pangaea.

The oldest Coastal Plain rocks that are exposed at the surface are of Upper Cretaceous age. These rocks are exposed at the surface in the region between Columbus and Macon and are composed mainly of sandstones, shales, and marls, many containing well-preserved fossils. These fossils and the nature of the sedimentary strata that contain them indicate that they formed in a coastal setting when the sea level was higher than it is today. The deposits accumulated in estuaries, tidal flats, lagoons, barrier islands, and in the shallow sea just offshore. As sea level fluctuated during the Cretaceous, the location of the shore shifted back and forth, leaving deposits all the way from Columbus to Lumpkin. The vertical, unconsolidated sandstone bluffs of Providence Canyon State Park, west of Lumpkin, represent the top formation of these Cretaceous strata. In the region from Macon to Augusta, Cretaceous strata are covered by younger rocks except in river valleys, where stream erosion has cut through the overlying strata to expose the Cretaceous underneath.

Fossils found in the Cretaceous deposits include large numbers of marine invertebrates, including clams, oysters, snails, and extinct Nautilus-like mollusks called ammonites. Also found is a rich collection of vertebrate fossils, notably the remains of duckbill dinosaurs, giant crocodiles, pterosaurs, and the recently discovered Appalachiosaurus montgomeriensis, a relative of the famous Tyrannosaurus rex.

Most of Georgia's Coastal Plain strata formed during the Paleogene period, which covers the time frame from the extinction of the dinosaurs up to what is commonly known as the Ice Ages. These deposits vary widely in their appearance and composition. In many areas, Paleogene Coastal Plain deposits are sandstone, shale, and mudrocks, which are very similar to the Upper Cretaceous rocks beneath them. Like those older deposits, Paleogene strata also formed at or near the ancient coast during times when the sea level was higher than it is today. During the Eocene epoch, sea level was particularly high, and limestone deposits formed extensively in southwestern Georgia; today, these rocks underlie the Dougherty Plain west and south of Albany. The Eocene limestones are very porous and form a major groundwater aquifer system that provides the main source of groundwater in the region. In the central and eastern Georgia Coastal Plain, Paleogene strata are represented by deposits that formed both in coastal and shallow-sea settings as well as in river floodplains adjacent to the coast.

Paleogene Coastal Plain strata are also fossiliferous and often contain well-preserved remains of ancient organisms. Indeed, the official Georgia state fossil is the tooth of the giant fossil shark, Carcharocles (formerly Carcharodon) megalodon. Also found are the remains of an ancient whale, which still retains remnants of hind legs from the time when the whale's ancestors lived on land.

Because Georgia's Coastal Plain strata all decline gently toward the modern coast, the youngest geological deposits in the state are in lowcountry, or coastal Georgia. These strata represent geological formation in coastal settings.

Georgia's coast consists of a chain of sandy barrier islands called the Sea Islands. These islands were inhabited by Native Americans long before the arrival of Europeans in the sixteenth century, and they were later the site of African American communities founded by fugitives from slavery. Today, Georgia's Sea Islands are important tourist destinations. The islands are mainly composed of beach and dune sand, which is constantly washed by waves and blown about by the persistent sea and land breezes. The islands are called barrier islands because they are separated from the mainland by shallow lagoons and marshes.

The highest tidal range along the southeastern shoreline from Cape Hatteras, North Carolina, to Miami Beach, Florida, occurs along the Georgia coast. For this reason tidal marshes and mud flats are extensively developed between the sandy Sea Islands and the mainland. The lagoons, marshes, and flats are of great importance to the coastal economy, both because they function as nurseries for young fish and because the sea grasses that grow on the tidal marshes provide a major source of nutrients to coastal fish.

Just inland from the coast are a series of low sand ridges running from north to south in lowcountry Georgia; these ridges represent former positions of the shore that formed at times of higher sea level during the Pleistocene epoch. The Pleistocene, also known as the Ice Ages, was a time of changing sea levels as the great continental glaciers of northern North America and Eurasia advanced and retreated. For this reason there are today in Georgia five or more of these low sand ridges, almost like stair-steps down to the sea.

In the Valley and Ridge Province, important geological resources include limestones and dolostones. These rocks are used in many ways, including as crushed stone and dimension stone. Limestones are of particular importance as a source of lime for the manufacture of cement and concrete. Both limestone and dolostone are also used in the chemical industry.

Pennsylvanian sandstones from the top of Sand Mountain and Lookout Mountain have been used as building and dimension stone. Perhaps of more importance are the coal deposits in the Appalachian Plateau province. Although these coals are not as thick or abundant in Georgia as they are in adjacent Alabama and Tennessee, they have been mined locally for many years. An unintended benefit of coal-mining is piles of waste rock, mainly shales, from the mining operations; in these shales preserved plant fossils may be found.

Another aspect of Georgia's geological bounty is the land itself. Georgia is widely known for its natural beauty, and visitors from around the nation and the world come every year to see and enjoy Georgia's scenery. Tourists visit the Sea Islands to bathe in the ocean, the Blue Ridge Mountains to gaze down into the spectacular Tallulah Gorge, southwest Georgia to visit Providence Canyon, or northwest Georgia to see Rock City or camp at Cloudland Canyons. Highlighting the state's natural beauty are the many state parks in Georgia.

A vital resource, though sometimes not thought of as geological, is water. Georgia has abundant clean-water resources, but groundwater is also a major resource in the state and is being utilized more and more as the needs of agriculture, industry, and Georgia's communities grow.

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But the story of Georgia's geology is not just about the past. Georgia is rich in such geological resources as marble, granite, and kaolin; production of these resources accounts for a large proportion of Georgia's wealth. In addition, the geological beauties of rock, river, and mountain provide the attractions that annually draw thousands of tourists to Georgia's state parks and other recreational areas.

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Apply cause and effect to Providence Canyon

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Applying Cause & Effect to the Phenomenon of ______________

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What new information can we find to answer our questions?

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Stop at different points of the video and have students make predictions.

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What questions do you have?

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Resources from the DOE TRL