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Sinkholes

Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces, then a sudden collapse of the land surface can occur. These collapses can be small, or, as this picture shows, or they can be huge and can occur where a house or road is on top.

The most damage from sinkholes tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania.

What is a "sinkhole"?

A sinkhole is an area of ground that has no natural external surface drainage--when it rains, the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes can vary from a few feet to hundreds of acres and from less than 1 to more than 100 feet deep. Some are shaped like shallow bowls or saucers whereas others have vertical walls; some hold water and form natural ponds.

Typically, sinkholes form so slowly that little change is noticeable, but they can form suddenly when a collapse occurs. Such a collapse can have a dramatic effect if it occurs in an urban setting.

Areas prone to collapse sinkholes

The map below shows areas of the United States where certain rock types that are susceptible to dissolution in water occur. In these areas the formation of underground cavities can form, and catastrophic sinkholes can happen. These rock types are evaporites (salt, gypsum, and anhydrite) and carbonates (limestone and dolomite). Evaporite rocks underlie about 35 to 40 percent of the United States, though in many areas they are buried at great depths.

Types of sinkholes

Since Florida is prone to sinkholes, it is a good place to use to discuss some different types of sinkholes and the geologic and hydrologic processes that form them. The processes of dissolution, where surface rock that are soluble to weak acids, are dissolved, and suffusion, where cavities form below the land surface, are responsible for virtually all sinkholes in Florida.
DISSOLUTION SINKHOLES
Dissolution of the limestone or dolomite is most intensive where the water first contacts the rock surface. Aggressive dissolution also occurs where is focused in preexisting openings in the rock, such as along joints, fractures, and bedding planes, and in the zone of water-table fluctuation where groundwater is in contact with the atmosphere.

Rainfall and surface water through joints in the limestone. Dissolved carbonate rock is carried away from the surface and a small depression gradually forms. On exposed carbonate surfaces, a depression may focus surface drainage, accelerating the dissolution process. Debris carried into the developing sinkhole may plug the outflow, ponding water and creating . Gently rolling hills and shallow depressions caused by solution sinkholes are common topographic features throughout much of Florida.
COVER-SUBSIDENCE SINKHOLES
Cover-subsidence sinkholes tend to develop gradually where the covering sediments are permeable and contain sand. In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.

1. Granular sediments spall into secondary openings in the underlying carbonate rocks.

2. A column of overlying sediments settles into the vacated spaces (a process termed "piping").

3. Dissolution and infilling continue, forming a noticeable depression in the land surface.\

4. The slow downward erosion eventually forms small surface depressions 1 inch to several feet in depth and diameter.

In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.
COVER-COLLAPSE SINKHOLES
Cover-collapse sinkholes may develop abruptly (over a period of hours) and cause catastrophic damages. They occur where the covering sediments contain a significant amount of clay. Over time, surface drainage, erosion, and deposition of sinkhole into a shallower bowl-shaped depression. Over time, surface drainage, erosion, and deposition of sediment transform the steep-walled sinkhole into a shallower bowl-shaped depression.

1. Sediments spall into a cavity

2. As spalling continues, the cohesive covering sediments form a structural arch.

3. The cavity migrates upward by progressive roof collapse.

4. The cavity eventually breaches the ground surface, creating sudden and dramatic sinkholes.

Sinkholes can be human-induced

New sinkholes have been correlated to land-use practices, especially from groundwater pumping and from construction and development practices. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created. The substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.

The overburden sediments that cover buried cavities in the aquifer systems are delicately balanced by groundwater fluid pressure. The water below ground is actually helping to keep the surface soil in place. Groundwater pumping for urban water supply and for irrigation can produce new sinkholes in sinkhole-prone areas. If pumping results in a lowering of groundwater levels, then underground structural failure, and thus, sinkholes, can occur.

Do you think you know about groundwater?
Take our Groundwater true/false quiz, part of our Activity Center.
Sources and more information Quiz icon made by mynamepong from www.flaticon.com​​​​​​​​​​​​​​

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Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big.

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Groundwater and aquifers

I hope you appreciate my spending an hour in the blazing sun to dig this hole at the beach. It is a great way to illustrate the concept of how, below a certain depth, the ground, if it is permeable enough to hold water, is saturated with water. The upper surface of this zone of saturation is called the water table. The saturated zone beneath the water table is called an aquifer, and aquifers are huge storehouses of water. What you are looking at in this picture is a "well" that exposes the water table, with an aquifer beneath it. Of course, I am cheating here, as at the beach, the level of the water table is always at the same level as the ocean, which is just below the surface of the beach.

Groundwater is one of our most valuable resources-even though you probably never see it or even realize it is there. As you may have read, most of the void spaces in the rocks below the water table are filled with water. These rocks have different porosity and permeability characteristics, which means that water does not move around the same way in all rocks below ground.

When a water-bearing rock readily transmits water to wells and , it is called an aquifer. can be drilled into the aquifers and water can be pumped out. Precipitation eventually adds water () into the porous rock of the aquifer. The rate of recharge is not the same for all aquifers, though, and that must be considered when pumping water from a well. Pumping too much water too fast draws down the water in the aquifer and eventually causes a well to yield less and less water and even . In fact, pumping your well too much can even cause your neighbor's well to run dry if you both are pumping from the same aquifer.

Visualizing groundwater

In the diagram below, you can see how the ground below the water table (the blue area) is saturated with water. The "unsaturated zone" above the water table (the gray area) still contains water (after all, plants' roots live in this area), but it is not totally saturated with water. You can see this in the two drawings at the bottom of the diagram, which show a close-up of how water is stored in between underground rock particles.

Sometimes the porous rock layers become tilted in the earth. There might be a confining layer of less porous rock both above and below the porous layer. This is an example of a confined aquifer. In this case, the rocks surrounding the aquifer confines the pressure in the porous rock and its water. If a well is drilled into this "pressurized" aquifer, the internal pressure might (depending on the ability of the rock to transport water) be enough to push the water up the well and up to the surface without the aid of a pump, sometimes completely out of the well. This type of well is called artesian. The pressure of water from an artesian well can be quite dramatic.

A relationship does not necessarily exist between the water-bearing capacity of rocks and the depth at which they are found. A very dense granite that will yield little or no water to a well may be exposed at the land surface. Conversely, a porous sandstone may lie hundreds or thousands of feet below the land surface and may yield hundreds of gallons per minute of water. Rocks that yield freshwater have been found at depths of more than 6,000 feet, and salty water has come from oil wells at depths of more than 30,000 feet. On the average, however, the porosity and permeability of rocks decrease as their depth below land surface increases; the pores and cracks in rocks at great depths are closed or greatly reduced in size because of the weight of overlying rocks.

Pumping can affect the level of the water table

Groundwater occurs in the saturated soil and rock below the water table. If the aquifer is shallow enough and permeable enough to allow water to move through it at a rapid-enough rate, then people can drill wells into it and withdraw water. The level of the water table can naturally change over time due to changes in weather cycles and precipitation patterns, streamflow and geologic changes, and even human-induced changes, such as the increase in impervious surfaces on the landscape.

The pumping of wells can have a great deal of influence on water levels below ground, especially in the vicinity of the well, as this diagram shows. If water is withdrawn from the ground at a faster rate that it is replenished, either by infiltration from the surface or from , then the water table can become lower, resulting in a "cone of depression" around the well. Depending on geologic and hydrologic conditions of the aquifer, the impact on the level of the water table can be short-lived or last for decades, and it can fall a small amount or many hundreds of feet. Excessive pumping can lower the water table so much that the wells no longer supply water-they can "go dry."

Water movement in aquifers

Water movement in aquifers is highly dependent of the permeability of the aquifer material. Permeable material contains interconnected cracks or spaces that are both numerous enough and large enough to allow water to move freely. In some permeable materials groundwater may move several meters in a day; in other places, it moves only a few centimeters in a century. Groundwater moves very slowly through relatively impermeable materials such as clay and shale. (Source: Environment Canada)

After entering an aquifer, water moves slowly toward lower lying places and eventually is discharged from the aquifer from springs, seeps into streams, or is withdrawn from the ground by wells. Groundwater in aquifers between layers of poorly permeable rock, such as clay or shale, may be confined under pressure. If such a confined aquifer is tapped by a well, water will rise above the top of the aquifer and may even flow from the well onto the land surface. Water confined in this way is said to be under artesian pressure, and the aquifer is called an artesian aquifer.

Visualizing artesian pressure

Here's a little experiment to show you how artesian pressure works. Fill a plastic sandwich baggie with water, put a straw in through the opening, tape the opening around the straw closed, point the straw upward (but don't point the straw towards your teacher or parents!) and then squeeze the baggie. Artesian water is pushed out through the straw.

Do you think you know about groundwater?
Take our Groundwater true/false quiz, part of our Activity Center.
Quiz icon made by mynamepong from www.flaticon.com

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I hope you appreciate my spending an hour in the blazing sun to dig this hole at the beach. It is a great way to illustrate the concept of how, below a certain depth, the ground, if it is permeable enough to hold water, is saturated with water.

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A quarry is a place where rocks, sand, or minerals are extracted from the surface of the Earth. A quarry is a type of mine called an open-pit mine, because it is open to the Earth's surface. Another type of mine, a sub-surface mine, consists of underground tunnels or shafts.

The most common purpose of quarries is to extract stone for building materials. Quarries have been used for thousands of years. Ancient Egyptians built the Great Pyramids with massive limestone and granite blocks cut by hand from nearby quarries. Each of these blocks weighs many tons. In ancient Rome, slaves and criminals were often forced to do the extremely difficult work of cutting stones in marble, granite, and limestone quarries.
Quarrying History
Methods of extracting stone and other materials from quarries have changed since the first quarries were mined in the Aswan area of Egypt. The earliest quarries were mined with hammers, picks, and chisels made of stone or metals such as bronze and iron.

Even communities that did not have stone buildings created quarries. The Lakota culture of the Midwest region of the U.S. and Canada did not quarry stone to build monuments or houses. At a site in Pipestone National Monument, in the U.S. state of Minnesota, they quarried for stones to make calumets, or ceremonial smoking pipes. Calumets, made of a type of metamorphic rock called catlinite or pipestone, were important for creating lasting treaties, or agreements between groups of people.

Quarrying material for use in building materials was much more work. Stones had to be carried or dragged out of quarries manually. Stones could also be hauled with pulley systems involving ropes and moveable wooden tracks or sleds. This process often involved thousands of slaves and other workers.

On Easter Island, for example, almost the entire community had to be involved in the quarrying, carving, and transportation of statues. The rock for these statues, called moai, was hauled all over the island from one quarry. The heaviest moai weighs 86 tons. Scientists are still studying how these ancient Polynesian people transported their quarried rock.

Today, people use mechanical tools to mine quarries, including drilling equipment, blasting equipment, and hauling equipment. Industrial drills with diamond tips are used to cut into hard rock. Some miners use explosives to blast away unwanted material to access the desired rock. Finally, materials are hauled away by enormous mining trucks. Some mining trucks can carry more than 350 tons of material.

Dimension Stones and Aggregate

Different types of stones are mined for different purposes. The two most common types of quarry material are dimension stones and aggregate.

Large, precisely cut stones excavated from a quarry are called dimension stones. Dimension stones are used for constructing buildings and monuments, or for decorating the outside of buildings. They are also used for kitchen counters and roofing shingles. Headstones, polished dimension stones usually made of granite, are used to mark graves in many countries.

Sand, gravel or crushed rock excavated from a quarry is called aggregate. Aggregate is used in construction to create stable foundations for things like roads and railroad tracks.

Aggregate is also used to make concrete and asphalt. For this reason, asphalt and concrete plants are often built next to quarries. Asphalt is an oily substance that is mixed with aggregate for road construction. Concrete, invented by the ancient Romans, is a mixture of sticky stone cement and aggregate. The Romans depended on concrete and aggregate to build their vast system of roads and aqueducts, many of which are still standing today.

Quarries and the Environment

Quarries change their environment. They displace huge amounts of soil and plants, and force animals out of the area. Abandoned quarries rarely leave enough soil to allow life to return to the area.

Some abandoned quarries can fill with water, creating artificial lakes. Many of these lakes are clear and deep, creating a safe swimming environment for people and some aquatic animals, such as frogs and birds. Sometimes, however, lakes created by abandoned quarries have mining equipment left on the bottom, making them unsafe for swimming. Toxic materials exposed by mining activities can also leak into water at abandoned quarries.

Quarries are prone to flooding because they are sometimes dug below the water table. Environmentalists fear the toxic materials could seep into groundwater if an abandoned quarrys water reaches an areas water table. This is the concern surrounding the Berkeley Pit, a former copper quarry near Butte, Montana. The Berkeley Pit is one of the largest toxic waste sites in the U.S., and its water is within 61 meters (200 feet) of the areas water table.

To avoid contamination, miners must sometimes pump water out of quarries. Quarries are sealed from the surrounding water table. Abandoned quarries can also be turned into landfill s.

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Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Tim Gunther
Mary Crooks, National Geographic Society

Editors

Kara West
Jeannie Evers, Emdash Editing

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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A quarry is a place where rocks, sand, or minerals are extracted from the surface of the Earth. A quarry is a type of mine called an open-pit mine, because it is open to the Earth's surface. Another type of mine, a sub-surface mine, consists of underground tunnels or shafts.

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Morning Call: September 25, 2004

Due to newsroom front-end system production difficulties the entire text could not be electronically captured for the online archive, please see microfilm for complete map.

For the first time, a state official Friday publicly blamed a Stockertown quarry for contributing to a rash of sinkholes that has disrupted traffic and damaged private property in parts of Northampton County for four years.

But Gary Hoffman, deputy secretary of operations for the state Department of Transportation, stopped short of blaming Hercules Cement Co. for a sinkhole that damaged a northbound Route 33 bridge in January and led to its $3.5 million replacement as well as the state's decision to replace the southbound bridge.

Hoffman said it was PennDOT's fault the northbound bridge over the Bushkill Creek failed because the state did not take into account the region's porous geology when the span was built in the 1970s.

"We know that the quarry is unquestionably a contributor," Hoffman told residents and government officials at Memorial Library of Nazareth and Vicinity. "But to say it is 50 percent, 60 percent of the problem or 90 percent of the problem, I think none of us can say that."

Hercules officials did not attend the meeting, which elected officials called to brief residents on an 8-month-old joint state and federal probe into the sinkholes and a new plan to slow sinkhole development in and around the Bushkill.

Joe Pospisil, Hercules' vice president of manufacturing, could not be reached. However, he has said there is no proof that the 98- year-old company is responsible because sinkholes form naturally in limestone-rich regions. Two other Nazareth area quarries -- Essroc

Italcementi Group and Eastern Industries Inc. -- have made the same argument.

The sinkhole plan, which residents oppose and is being reviewed by the state Department of Environmental Protection and U.S. Army Corps of Engineers, calls for Hercules and PennDOT to jointly line 850 feet of the creek, up to the state-owned land around the Route 33 bridges, with a synthetic material.

The state hopes the plastic membrane, which Hercules has a separate permit to use at two other stream locations farther north, will stop creek water from draining into the ground and causing sinkholes. The lining would then reduce the amount of creek water flowing underground through sinkholes and into the quarry.

Hoffman said he knows the lining won't solve the overall sinkhole problem, but it's the best short-term solution to protect the bridges. He added the lining would help protect the creek if the Corps receives federal approval and local or state assistance to line more of the stream bed.

However, he said, if the joint plan is approved, PennDOT would not begin its share of the work if studies show the lining would have a detrimental effect on residents downstream of Route 33.

In not blaming Hercules for the sinkhole under the Route 33 bridge, Hoffman said sinkholes have been opening in the area for generations.

"Those bridges should have been on deep foundations to begin with, but that is literally water down the hole now," Hoffman said. "There were probably sinkholes developing out there before the quarry. There's going to be sinkholes developing if the quarry went away."

Studies have shown that quarries can cause sinkholes when they pump groundwater out of their pits. The pumping creates a massive underground funnel called the "cone of depression" or "zone of influence." Groundwater is sucked up through the cone, which then buckles the surface above until a hole opens.

Based on Hercules' own groundwater studies, which DEP uses as its official records, the quarry's cone is believed to cover 2.2 square miles, stopping on the east side of the northbound Route 33 bridge. The studies estimate Hercules' cone will grow an additional 1.3 square miles when the quarry, now 300 to 330 feet deep, uses DEP's March 2003 approval to mine deeper.

Although state officials previously acknowledged the size of Hercules' cone, no one said Hercules has contributed to the sinkholes, which began opening in 2000 when a Palmer Township family was forced from their home and the small Stockertown-Tatamy bridge was swallowed.

DEP mining inspector Mike Menghini said Friday that although the state granted Hercules' a "conditional approval" to mine an additional 150 feet, the agency is now having second thoughts.

"We are not comfortable with them going deeper. We want them to go laterally," Menghini said. "We could stop [the permit] if it shows an effect they cannot remediate, but then they can appeal that."

Steve Esack

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Morning Call: September 25, 2004 Due to newsroom front-end system production difficulties the entire text could not be electronically captured for the online archive, please see microfilm for complete map. For the first time, a state official Friday publicly blamed a Stockertown quarry for contributing to a rash of sinkholes that has disrupted traffic and damaged private property in parts of Northampton County for four years.

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What is a sinkhole?

Sinkholes are part of the slow, natural process of erosion in Florida's limestone terrain that occur over thousands of years. These common geologic phenomena generally occur where the limestone is within a few hundred feet of the land's surface.

Though most are only 10 to 12 feet in diameter, sinkholes have been known to expand to hundreds of feet in diameter. Many of central and north Florida's lakes actually are the result of old sinkholes.

How do sinkholes form?

Rainfall percolating, or seeping, through the soil absorbs carbon dioxide and reacts with decaying vegetation, creating a slightly acidic water. That water moves through spaces and cracks underground, slowly dissolving limestone and creating a network of cavities and voids. As the limestone dissolves, pores and cracks are enlarged and carry even more acidic water. Sinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids.

Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form. Also, heavy rains after droughts often cause enough pressure on the ground to create sinkholes.

Sinkholes can be triggered by human activities such as:

Overwithdrawal of groundwater

Diverting surface water from a large area and concentrating it in a single point

Artificially creating ponds of surface water

Drilling new water wells

In urban or suburban areas, sinkholes are hazardous because they can destroy highways and buildings. Sinkholes also can cause water quality problems. During a collapse, surface waters may leak into the aquifer, our underground source of drinking water.

Can sinkholes be prevented?

Many natural sinkholes cannot be prevented. However, those caused by human activity may be avoided, especially those caused by over-pumping groundwater. During dry conditions, water tables drop in the limestone and cavities under Florida's sand and clay soil. The combination of gravity, loss of buoyancy and water pressure can activate a collapse.

By keeping water tables high, water conservation rules and drought restrictions are tools to help prevent sinkholes from occurring. The St. Johns River Water Management District promotes year-round water conservation and issues watering restrictions to prevent water shortages and over-pumping during Florida's inevitable times of drought.

The district is responsible for providing long-term protection of the water supply. While water restrictions can cause some inconvenience to residents and businesses, limiting outdoor watering is critical throughout the year, and especially during a drought. Public cooperation is vital to ensuring long-term water resource protection.

Warning signs

A rapid sinkhole caused by well drilling or other sudden alterations to the terrain may not give any warning signs. Otherwise, the collapse process usually occurs gradually enough that a person may leave the affected area safely. The final breakthrough can develop over a period of a few minutes to a few hours.

Some warning signs of a naturally occurring sinkhole include:

Gradual localized ground settlement

Doors and windows fail to close properly

Cracks in a foundation

A circular pattern of ground cracks outlining the sinking area

Vegetation stress due to a lowered water table

Turbidity in local well water due to sediment washing into the limestone's pores

There are many other causes of localized ground settlement and vegetation stress, and depressed areas are not necessarily indications of an imminent sinkhole.

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Sinkholes are part of the slow, natural process of erosion in Florida's limestone terrain that occur over thousands of years. These common geologic phenomena generally occur where the limestone is within a few hundred feet of the land's surface.

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Image

A water well system next to a house, showing how aquifers are an important source of water.

Graphic by NosorogUA

Encyclopedic Entry Vocabulary

An aquifer is a body of rock and/or sediment that holds groundwater. Groundwater is the word used to describe precipitation that has infiltrated the soil beyond the surface and collected in empty spaces underground.

There are two general types of aquifers: confined and unconfined. Confined aquifers have a layer of impenetrable rock or clay above them, while unconfined aquifers lie below a permeable layer of soil.

Many different types of sediments and rocks can form aquifers, including gravel, sandstone, conglomerates, and fractured limestone. Aquifers are sometimes categorized according to the type of rock or sediments of which they are composed.

A common misconception about aquifers is that they are underground rivers or lakes. While groundwater can seep into or out of aquifers due to their porous nature, it cannot move fast enough to flow like a river. The rate at which groundwater moves through an aquifer varies depending on the rock's permeability.

Much of the water we use for domestic, industrial, or agricultural purposes is groundwater. Most groundwater, including a significant amount of our drinking water, comes from aquifers. In order to access this water, a well must be created by drilling a hole that reaches the aquifer. While wells are manmade points of discharge for aquifers, they also discharge naturally at springs and in wetlands.

Groundwater can become depleted if we use it at a faster rate than it can replenish itself. The replenishment of aquifers by precipitation is called recharging. Depletion of aquifers has increased primarily due to expanding agricultural irrigation. Groundwater can become contaminated when an excessive amount of pesticides and herbicides are sprayed on agricultural fields, septic tanks leak, or landfills are improperly lined or managed and toxic materials seep through the soil into the aquifer.

Aquifers naturally filter groundwater by forcing it to pass through small pores and between sediments, which helps to remove substances from the water. This natural filtration process, however, may not be enough to remove all of the contaminants.

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Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society
Margot Willis, National Geographic Society

Specialist, Content Production

Clint Parks

Producer

Andre Gabrielli, National Geographic Society

Last Updated

July 30, 2019

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Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society
Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society
Margot Willis, National Geographic Society

Specialist, Content Production

Clint Parks

Producer

Andre Gabrielli, National Geographic Society

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Image A water well system next to a house, showing how aquifers are an important source of water. Graphic by NosorogUA Encyclopedic Entry Vocabulary An aquifer is a body of rock and/or sediment that holds groundwater. Groundwater is the word used to describe precipitation that has infiltrated the soil beyond the surface and collected in empty spaces underground.

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Production Credits:
Producer: Scott Leigh
Executive Producer: Melanie Eirich
Graphic Designer: Lisa Craig
Contributing Producer for QUEST Nebraska: Gary Hochman
Educational Review: Anica Brown

Pre-Discussion Questions for Aquifers

How would you describe an aquifer?

Why are aquifers important?

Is it possible for an aquifer to run dry? Why or why not?

Which state in the U.S. do you think uses the most groundwater and why?

Focus Discussion for Aquifers

Why are aquifers important to us?

How does water get into an aquifer?

What type of aquifer is the Ogallala (High Plains) Aquifer?

All of the water on the earth is suitable for drinking. True or False?

Post-Discussion Questions for Aquifers

Is an aquifer the same as an underground lake or river? Why or why not?

What are the two types of aquifers? Describe them and how the water is stored or found in each.

What are some ways that an aquifer can be depleted, contaminated, and replenished?

What is the result when water is pumped faster from a well than the aquifer near the well can be recharged?

What are groundwater monitoring wells and why are they important?

Links to Learn More

Aquifer Basics, USGS - A page from the USGS Groundwater Information series on their website.

National Geographic Education: Aquifer, National Geographic - A very basic look at the "anatomy" of an aquifer.

Ground-Level Changes in Nebraska, University of Nebraska-Lincoln, School of Natural Resources - Maps, maps, maps from the University of Nebraska-Lincoln's School of Natural Resources! These are large, downloadable maps in different formats comparing groundwater levels during different periods of time.

The Price of Water, NET -An NET Television documentary with segments on the Ogallala Aquifer, groundwater and tap water.

Tapping unsustainable groundwater stores for agricultural production in the High Plains Aquifer, PNAS -This page provides an extended abstract for the 2013 article (based on four years of research) that created an outpouring of concern when the authors' argued that "agriculture is tapping the High Plains Aquifer beyond natural replenishment rates to grow irrigated crops and livestock." The abstract page links to the full text of the original article.

How long before the Great Plains run out of water? The Washington Post - A Washington Post article based on a recent major study of the Ogallala Aquifer.

Running Dry on the Great Plains, The New York Times - A New York Times Op-Ed piece claiming that the aquifer is being wasted and polluted.

NGSS Correlations

Performance Expectation: Construct a scientific explanation based on evidence for how the uneven distributions of Earth's mineral, energy, and groundwater resources are the result of past and current geoscience processes. MS-ESS2 Earth's Systems

Disciplinary Core Idea: The Role of Water in Earth's Surface Processes: Water continually cycles among land, ocean, and atmosphere via transpiration, evaporation, condensation and crystallization, and precipitation, as well as downhill flows on land. MS - ESS2.C

Science & Engineering Practices: Developing and Using Models, Constructing Explanations and Designing Solutions & Engaging in Argument from Evidence.

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Production Credits: Producer: Scott Leigh Executive Producer: Melanie Eirich Graphic Designer: Lisa Craig Contributing Producer for QUEST Nebraska: Gary Hochman Educational Review: Anica Brown How would you describe an aquifer? Why are aquifers important? Is it possible for an aquifer to run dry? Why or why not? Which state in the U.S.

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Why do sinkholes seem so common in Baltimore? The city has a long history of unpredictable infrastructure.

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Baltimore's geology and decaying infrastructure produce frequent street collapses and sinkholes.

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Get access to files anywhere through secure cloud storage and file backup for your photos, videos, files and more with Google Drive.

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Watch as rainwater, waves, lava, and bacteria create four different types of caves.

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Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to the removal or movement of subsurface earth material.