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Earth Science for Kids: Rocks, Rock Cycle, and Formation

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Kids learn about the science of rocks and the rock cycle. How different types such as igneous, sedimentary, and metamorphic form from minerals with the help of nature.

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Geologists classify rocks into three basic groups based on how they were formed in nature.

The types of rocks are:

Igneous

Sedimentary

Metamorphic

To help you identify the types of rocks in your collection, let's look at the characteristics that make up the three types. First, we will look at igneous rocks.

Igneous Rock Specimen: Serpentine

A FAMILY OF SILICATE MINERALS RICH IN MAGNESIUM AND WATER, DERIVED FROM LOW-TEMPERATURE ALTERATION OR METAMORPHISM OF THE MINERALS IN ULTRAMAFIC ROCKS.

ROCKS MADE UP OF SERPENTINE MINERALS ARE CALLED SERPENTINITE.

SERPENTINE MINERALS ARE LIGHT TO DARK GREEN, COMMONLY VARIED IN HUE, AND GREASY LOOKING; THE MINERAL FEELS SLIPPERY.

(CREDIT: U.S. GEOLOGICAL SURVEY)

Sedimentary Rock Specimen:

Shale

SEDIMENTARY ROCK DERIVED FROM MUD. COMMONLY FINELY LAMINATED (BEDDED). PARTICLES IN SHALE ARE COMMONLY CLAY MINERALS MIXED WITH TINY GRAINS OF QUARTZ ERODED FROM PRE-EXISTING ROCKS. SHALEY MEANS LIKE A SHALE OR HAVING SOME SHALE COMPONENT, AS IN SHALEY SANDSTONE. (CREDIT: U.S. GEOLOGICAL SURVEY)

Metamorphic Rock Specimen:

Slate
SLATE IS A METAMORPHIC ROCK. METAMORPHIC ROCKS ARE FORMED WHEN SEDIMENTARY OR IGNEOUS ROCKS ARE EXPOSED TO CONDITIONS OF VERY HIGH PRESSURE OR TEMPERATURE, OR ARE EXPOSED TO LARGE AMOUNTS OF VERY HOT WATER. SLATE IS FORMED WHEN FINE-GRAINED SEDIMENTARY ROCK (SHALE) IS BURIED AND EXPOSED TO HIGH PRESSURE DEEP BENEATH THE EARTH'S SURFACE. SLATE, LIKE MANY, BUT NOT ALL, METAMORPHIC ROCKS IS CHARACTERIZED BY THE WAY IT BREAKS, ALONG CLOSELY SPACED PARALLEL FRACTURES. (CREDIT: U.S. GEOLOGICAL SURVEY)

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Geologists classify rocks into three basic groups based on how they were formed in nature. The types of rocks are: Igneous Sedimentary Metamorphic To help you identify the types of rocks in your collection, let's look at the characteristics that make up the three types. First, we will look at igneous rocks.

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Fun Rock Facts for Kids - Information about Types of Rocks & Minerals

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Let's start off with an explanation that rocks and minerals are different things. Rocks are groups of different minerals pushed together and combined. They don't have easy chemical formulas to describe their makeup. A ruby is considered a mineral. It's a nice pretty crystal with the same compounds throughout the object. But the rock that surrounds that ruby has many many different compounds (and even a few pieces of ruby mixed in). There's an easier example that many people can relate to. Think about quartz. On its own (as a mineral) it's a nice pretty crystal. But a piece of granite often has loads of quartz. It's ground up and crushed, but its still bits of quartz. Granite is a rock and quartz is a mineral.

Igneous rocks are the ones that were superheated and originally liquid. They come from the center of the Earth! Not really the center, but they often start their lives below the crust and then get pumped out. There are two basic types of igneous rocks. There are the rocks that make it to the surface (extrusive) and the ones that are stuck in the crust just below the surface (intrusive). These igneous types have all hardened after being molten rock. If you walk around a volcano, you will find those extrusive types. The intrusive types are usually found in areas called plutons and dikes, big old pools of molten rock that were just beneath the surface. Some examples of igneous rock are granite, all volcanic rock, basalt, and obsidian.

This rock type is created by heat and/or pressure. Even though heat is involved, they didn't start off as molten rock. But. You often find metamorphic rock near volcanoes and sources of super hot rock. The heat from the magma changes all of the rock around it. Try another explanation. Look at the name 'metamorphic.' It looks like the word used to describe insects that go through a metamorphosis. It's the same concept. Some force (heat/pressure) has changed these rocks from one type into a new type. The result is a metamorphic rock. Some examples are marble, jade, slate, and gneiss. Because pressure and heat are involved, these rock types are usually found deep beneath the surface. They are also found near fault lines where plates push against each other and create enormous pressures. Over time, because of the movement of the crust, these metamorphic rocks are pushed to the surface where you can find them every day.

The last of the big three rock types is probably the rarest... unless you live near the coast. Sedimentary rock types are created when sediment compresses. It's pretty simple. Here's the setup... A river flows through a canyon and picks up a bunch of silt. That sediment and silt runs downstream and deposits where the river ends. It could be in a flood plain or a valley, but we're using a coastline as an example. When that material gets to the beach, it sits there. Now if you watch this happen over millions of years, more and more sediment builds up and compacts. That compacted sediment eventually becomes a type of rock. Examples of sedimentary rock include sandstone, amber, anthracite, and limestone.

That's right, not all rocks are from Earth. Sure you can debate whether a meteorite is a rock, but you definitely find them all over the Earth. Some super big ones have created massive craters across the globe. Most scientists now believe that a super-massive meteorite hit the Earth and created an extinction event for the dinosaurs. There are also millions of tiny meteorites. They look just like rocks until you break them open. Meteorites are mainly made of iron and nickel. You will also find many smaller trace elements. The key thing to remember about meteorites is that they have much different percentages of elements than rocks on Earth. Many trace elements found on these space travelers are nearly impossible to find on Earth.

Or search the sites for a specific topic.

Our World: The Rock Cycle (NASA eClips Video)

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Geography4Kids.com: Earth Structure: Rock Types

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Let's start off with an explanation that rocks and minerals are different things. Rocks are groups of different minerals pushed together and combined. They don't have easy chemical formulas to describe their makeup. A ruby is considered a mineral. It's a nice pretty crystal with the same compounds throughout the object.

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Types Of Rocks | The Dr. Binocs Show | Learn Videos For Kids

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3 Types of Rocks | #aumsum #kids #science #education #children

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3 Rocks Types Igneous rocks,Sedimentary rocks,Metamorphic rocks for kids

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Rocks and Minerals For Kids | Science For Kids | Grade 2 | Periwinkle

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The 3 Types of Rocks | Educational Science Rap Curriculum

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Properties of Rocks: Lesson for Kids - Lesson | Study.com

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Investigate the various properties and characteristics of rocks. Discover how rocks vary in color, texture, shape, size, luster, and hardness.…

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Igneous Rocks video for kids by makemegenius.com

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Sedimentary Rocks Video for kids by makemegenius.com

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Fossils and Rock Identification for Kids

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Rock cycle video |  Learn about Types of Rocks | Rock cycle for kids

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Rocks Types & Rocks Cycle  - Video for Kids by makemegenius.com

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Earth Science - Rock Cycle And Types Of Rock | iKen | iKen Edu | iKen App

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THE ROCK CYCLE SONG | Science Music Video

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Fun Rock Cycle Facts for Kids (All You Need to Know!)

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Humans use rocks for many different things - in particular, roofing and building materials. Is it possible to run out of rocks? Although we should always use natural resources carefully, it's not likely that we'll run out of rocks anytime soon. Rocks go through a continuous cycle of change.

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Rock Cycle Lesson for Kids: Definition & Facts - Lesson | Study.com

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Learn about the rock cycle in this informative video lesson for kids! Explore the key stages of this geological process and test your knowledge with an optional quiz.

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Let's say you made a cake and left it outside. What would happen? Maybe it would dry up and crack in the hot sun. Or perhaps rain would wash it away. If it froze, it might crack too. This process would probably take just a few days.

The Earth - and the rocks on the Earth - is a bit like that cake. The surface of the Earth is constantly being changed due to weathering processes. This process can take millions of years or happen relatively quickly.

Fun Facts about Weathering for Kids

Rain is mildly acidic and it slowly eats away rocks. Rain slowly dissolves limestone. It turns the feldspar in granite into soft clay. The remaining quartz crystals are often crushed into grains of sand.

Plants and microbes also attack rocks. All living things need elements, such as copper, potassium and iron, as nutrients. These minerals are found within rocks. Lichens grow on rocks and release acids to dissolve the minerals in them. Plant roots slowly grow into rocks, forcing them apart.

In cold areas, water seeps into cracks in the rocks during the day. At night, the water freezes and expands, cracking the rocks even more. This continual freeze and thaw cycle causes rocks to splinter and break into small pieces.

In the desert, rocks expand during the heat of the day and contract at night when temperatures cool. Sheets of rock slowly flake away.

Weathering Vocabulary

Learn More All About Weathering

Check out this cool video about Weathering for kids:

This video explains the factors and the process of weathering.

Weathering Q&A

Question: How are the types of weathering described?

Answer: Chemical weathering occurs when a chemical, such as acid rain, breaks down rocks. Mechanical weathering is the process of weathering through external forces, such as freeze and thaw cycles. When plants or microbes break down rocks, the process is known as organic weathering.

Enjoyed the Geography for Kids all about Weathering info? Take the FREE & fun all about Weathering quiz and download FREE Weathering worksheet for kids. For lengthy info click here.

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Let's say you made a cake and left it outside. What would happen? Maybe it would dry up and crack in the hot sun. Or perhaps rain would wash it away. If it froze, it might crack too. This process would probably take just a few days.

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Weathering is the breaking down of rocks, soil and their minerals through direct contact with the Earth's atmosphere, waters, or living things. It is a natural process.

Weathering occurs in one place with little or no movement, and should not be confused with erosion which is when rocks and minerals are moved to another place by ice, water, wind or gravity.

Mechanical weathering

Mechanical or physical weathering is when the rocks and minerals are broken down but the chemical composition remains the same. Mechanical weathering physically breaks up rock.

Wind can blow water or small particles such as sand against the rock thus breaking it down.

Rain is another force that works slowly. The force of raindrops on some rocks make them wear down. Rain also can make a chemical change in some rocks, because it is usually slightly acidic. The water mixes with the minerals in the rock to break it down.

Temperature

Changing temperature can make a rock crack. Every day when the sun shines on the rock, its surface is heated. Heat causes the surface to expand (get bigger) a little. The inside of the rock, though, does not heat up as fast as the outside of the rock. The inside of the rock stays cooler. At night, the surface cools down and contracts. The expanding and contracting makes some places on the surface weak, and a crack is made.

Also, if water gets into a crack in a rock and the temperature goes below the freezing point, the water will freeze and expand. After some time, the rock may be weak enough to break into pieces.

Ice, which can be miles thick, grinds the surface of the rock below it. The particles are carried with the ice, and if a glacier ends up in the sea, so does all the material carried with it.

Lava or magma

Lava or magma can cause weathering when molten rock touches older rock. It causes the older rock to change form to a different crystal structure.

Chemical weathering

Chemical weathering is the breaking down of rock which changes the chemical composition.

Carbon dioxide cycle

The carbon dioxide cycle is the most important for weathering. CO ₂ is put into the atmosphere mostly by volcanoes, and it is taken out of the atmosphere by photosynthesis, and by one other process.

While it is in the air, CO ₂ can dissolve in water droplets to form weak carbonic acid.

When rain hits rock it does so with mechanical energy and dilute acid. The acid dissolves many types of minerals and rocks though, of course, very slowly. When a mineral like feldspar is dissolved, it lets sodium ions into the sea; chlorine ions come from other minerals. The sea tastes salty because of the elements which have been dissolved out of rocks.

Weathering Media

A natural arch produced by erosion of differentially weathered rock in Jebel Kharaz ( Jordan)

Exfoliated granite sheets in Texas, possibly caused by pressure release

A pyrite cube has dissolved away from host rock, leaving gold particles behind.

Oxidized or "rusted" Pyrite cubes, in matrix. This is an important Redox chemical reaction in Acid mine drainage.

Related pages

References

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Weathering facts. Weathering is the breaking down of rocks, soil and their minerals through direct contact with the Earth's atmosphere, waters, or living things. It is a natural process.

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Weathering and Erosion: Crash Course Kids #10.2

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Erosion and Weathering for Kids -Causes and Differences