Rocks Here, There, Everywhere Mrs. Tweedie April 2008.

RocksRocks

Here, There, EverywhereHere, There, Everywhere

Mrs. TweedieApril 2008

You can find rocks just You can find rocks just about anywhere. One rock about anywhere. One rock can be very different from can be very different from another.another.

RocksRocks

Have you ever seen a rock Have you ever seen a rock with layers? Some of these with layers? Some of these rocks were formed under water. rocks were formed under water.

Sedimentary Sedimentary RocksRocks

They are made up of pieces of They are made up of pieces of other rocks and things like sand, other rocks and things like sand, clay, and mud that settled in layers clay, and mud that settled in layers under water. After a long time, the under water. After a long time, the layers piled up and stuck together.layers piled up and stuck together.

Sedimentary RocksSedimentary Rocks

Sometimes, plants, bones, or Sometimes, plants, bones, or sea shells got caught in the layers. sea shells got caught in the layers. They formed fossils. Some fossils They formed fossils. Some fossils are the prints of plants and animals are the prints of plants and animals that lived long ago.that lived long ago.


Other fossils are actual parts of Other fossils are actual parts of plants or animals that have been plants or animals that have been mineralized.mineralized.


Do you know what a pebble Do you know what a pebble is? If you look closely, you can is? If you look closely, you can see pebbles in some rocks that see pebbles in some rocks that formed under water.formed under water.


Conglomerate

Because these rocks are formed Because these rocks are formed of sediment, or bits and pieces of of sediment, or bits and pieces of matter that have settled to the matter that have settled to the bottom of water, scientists call bottom of water, scientists call them them sedimentary rocks.sedimentary rocks.


Sandstone

For thousands, For thousands, even millions of even millions of years, little pieces of years, little pieces of our earth have been our earth have been eroded--broken eroded--broken down and worn away down and worn away by wind and water. by wind and water. These little bits of These little bits of our earth are our earth are washed downstream washed downstream where they settle to where they settle to the bottom of the the bottom of the rivers, lakes, and rivers, lakes, and oceans. oceans.

Sedimentary Rocks SummarySedimentary Rocks Summary

Layer after Layer after layer of eroded layer of eroded earth is deposited earth is deposited on top of each on top of each previous layer. previous layer. These layers are These layers are pressed down pressed down more and more more and more through time, through time, until the bottom until the bottom layers slowly turn layers slowly turn into rock.into rock.

Sedimentary Rocks SummarySedimentary Rocks Summary

Some rocks were formed inside Some rocks were formed inside the earth. Deep inside the earth, it the earth. Deep inside the earth, it is very hot. In fact, it is so hot that is very hot. In fact, it is so hot that rocks melt! rocks melt!

Igneous RockIgneous Rock


Melted Melted underground underground rock is called rock is called magma. magma. Rocks formed Rocks formed from magma from magma are called are called igneous.igneous.


Sometimes Sometimes the magma the magma erupts through erupts through the surface of the surface of the earth. the earth. Rocks, flames, Rocks, flames, and steam and steam spout toward spout toward the sky.the sky.


When this happens, the When this happens, the magma gets a new name. It is magma gets a new name. It is called lava. As the lava piles up called lava. As the lava piles up and hardens, it forms a volcano.and hardens, it forms a volcano.


Rocks from volcanoes don’t Rocks from volcanoes don’t always look the same. Some always look the same. Some look like glass. They are smooth. look like glass. They are smooth. This is because they cooled fast. This is because they cooled fast.

Obsidian Rock


Other rocks from volcanoes Other rocks from volcanoes cooled slowly. Gas bubbled out, cooled slowly. Gas bubbled out, causing small holes to form. causing small holes to form. Their surface is often rough.Their surface is often rough.

Pumice


Volcanoes often erupt more Volcanoes often erupt more than once. As soon as the lava than once. As soon as the lava starts to harden, more lava lands starts to harden, more lava lands on top of it! on top of it!


Rocks formed this way have Rocks formed this way have bands, or streaks, in them.bands, or streaks, in them.

Granite


Sometimes the magma cools Sometimes the magma cools very slowly underground. Rocks very slowly underground. Rocks formed in this way are very hard formed in this way are very hard and heavy. You can see pieces of and heavy. You can see pieces of minerals in them.minerals in them.

Basalt

Igneous rocks are Igneous rocks are called fire rocks and called fire rocks and are formed either are formed either underground or above underground or above ground. Underground, ground. Underground, they are formed when they are formed when the melted rock, called the melted rock, called magma, deep within magma, deep within the earth becomes the earth becomes trapped in small trapped in small pockets. As these pockets. As these pockets of magma cool pockets of magma cool slowly underground, slowly underground, the magma becomes the magma becomes igneous rocks. igneous rocks.

Igneous Rock SummaryIgneous Rock Summary

Igneous rocks are Igneous rocks are also formed when also formed when volcanoes erupt, volcanoes erupt, causing the magma causing the magma to rise above the to rise above the earth's surface. earth's surface. When magma When magma appears above the appears above the earth, it is called earth, it is called lava. Igneous rocks lava. Igneous rocks are formed as the are formed as the lava cools above lava cools above ground.ground.

Igneous Rock SummaryIgneous Rock Summary

Metamorphic RockMetamorphic Rock

Rocks don’t always stay Rocks don’t always stay where they are formed. where they are formed. Overtime, earthquakes move Overtime, earthquakes move them around.them around.


As rocks are moved, they can As rocks are moved, they can change. They become twisted. change. They become twisted. They can even break up.They can even break up.


Heat also changes rocks. Heat also changes rocks. There is heat just under the There is heat just under the surface of the earth. surface of the earth.


It is not hot enough to turn It is not hot enough to turn rocks into liquid, but it is hot rocks into liquid, but it is hot enough to change them.enough to change them.


Rocks that have been Rocks that have been changed by underground changed by underground pressure or heat are called pressure or heat are called metamorphic.metamorphic.

Slate

Schist

Gneiss

marble

Metamorphic Rock SummaryMetamorphic Rock Summary

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change?

The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you examine metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

Metamorphic Rock SummaryMetamorphic Rock Summary

Rocks will give us clues about Rocks will give us clues about how and where they were how and where they were formed-if we take time to look at formed-if we take time to look at them closely.them closely.

RocksRocksHere, There, EverywhereHere, There, Everywhere

Rocks Here, There, Everywhere Mrs. Tweedie April 2008.

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