Types of Rocks!Types of Rocks!What do they have to say What do they have to say

to us?to us?

The 3 Types of Rocks:The 3 Types of Rocks: IgneousIgneous

Slow-CoolingSlow-Cooling Fast-CoolingFast-Cooling Flow DirectionFlow Direction

SedimentarySedimentary ChemicalChemical DetritalDetrital

MetamorphicMetamorphic FoliatedFoliated Non-FoliatedNon-Foliated

About the AuthorAbout the Author

Resource PageResource Page

Watch a video about the typesWatch a video about the types of rocks! of rocks!

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Click on the photo to visit a website about the rock

types!

Igneous RocksIgneous Rocks Igneous rocks are found by

volcanoes and in mountain belts

They form when melted rock cools and becomes a solid.

There are 3 prominent ways that igneous rocks form:

Some cool slowly and have bigger crystals

Some cool very fast and have small crystals

Some even show the direction of the lava flow.

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Slow-Cooling Igneous RocksSlow-Cooling Igneous Rocks

When magma stays underground, it cools very When magma stays underground, it cools very slowly.slowly. This allows time for the crystals to form which is why This allows time for the crystals to form which is why

there are larger crystals in slow-cooling rocksthere are larger crystals in slow-cooling rocks

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Fast-Cooling Igneous RocksFast-Cooling Igneous Rocks

On the other hand, magma can also cool very quickly if the On the other hand, magma can also cool very quickly if the temperature is suddenly lowered. This temperature change can temperature is suddenly lowered. This temperature change can occur when the magma is quenched either by air or water.occur when the magma is quenched either by air or water. The crystals have little time to form, therefore, fast-cooling rocks The crystals have little time to form, therefore, fast-cooling rocks

have smaller crystals than slow-cooling rocks.have smaller crystals than slow-cooling rocks.

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Igneous Rocks That Show Igneous Rocks That Show FlowFlow

When magma flows out of a volcano, it is called lava.When magma flows out of a volcano, it is called lava. While the lava is flowing, some of the lava begins to solidify While the lava is flowing, some of the lava begins to solidify

while the lava underneath is still molten. This molten lava while the lava underneath is still molten. This molten lava pushed through the solid rock and creates a unique rolling pushed through the solid rock and creates a unique rolling texturetexture

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Sedimentary RocksSedimentary Rocks Sedimentary Rocks are Sedimentary Rocks are

formed when rocks formed when rocks ‘settle out’ of water or ‘settle out’ of water or air.air.

There are 2 Types of There are 2 Types of Sedimentary RocksSedimentary Rocks

ChemicalChemicalDetritalDetrital

The rock pieces are then The rock pieces are then cemented together for cemented together for form Sedimentary Rocksform Sedimentary Rocks

They also contain many They also contain many fossils from millions of fossils from millions of years ago!years ago!

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Chemical Sedimentary Chemical Sedimentary RocksRocks

Chemical Sedimentary rocks form when chemicals, Chemical Sedimentary rocks form when chemicals, such as calcium carbonate, are precipitated out of such as calcium carbonate, are precipitated out of the water by organic or inorganic processes.the water by organic or inorganic processes.

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Detrital Sedimentary RocksDetrital Sedimentary Rocks

Detrital sedimentary rocks form when solid Detrital sedimentary rocks form when solid particles are transported and then accumulate.particles are transported and then accumulate.

They occur as a result of chemical or mechanical They occur as a result of chemical or mechanical weathering.weathering.

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Metamorphic RocksMetamorphic Rocks Metamorphic Rocks are Metamorphic Rocks are

found in areas that have found in areas that have been under lots of pressure been under lots of pressure and/or temperature.and/or temperature.

ex: mountainsex: mountains There are 2 types of There are 2 types of

Metamorphic Rocks:Metamorphic Rocks:FoliatedFoliatedNon-foliatedNon-foliated

They can form from either They can form from either igneous rocks or igneous rocks or sedimentary rockssedimentary rocks

Sandstone changes to Sandstone changes to quartzitequartzite

Granite changes to gneiss Granite changes to gneiss (which is shown at the right)(which is shown at the right)

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Foliated Metamorphic RocksFoliated Metamorphic Rocks

As a result of compression and stress on the rock, As a result of compression and stress on the rock, the minerals within the rock align themselves the minerals within the rock align themselves perpendicular to the direction of stress.perpendicular to the direction of stress. This alignment creates the banding/foliation in the rock.This alignment creates the banding/foliation in the rock.

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Non-Foliated Metamorphic Non-Foliated Metamorphic RocksRocks

In general, many non-foliated rocks have not undergone a In general, many non-foliated rocks have not undergone a great amount of stress, and therefore, do not show foliation.great amount of stress, and therefore, do not show foliation.

Also, the minerals that compose non-foliated rocks are Also, the minerals that compose non-foliated rocks are equidimensional crystals. As a result, no foliation would equidimensional crystals. As a result, no foliation would appear because all the mineral grains look similar. appear because all the mineral grains look similar.

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A Little Bit About Me…A Little Bit About Me…

My name is Laura Donker, and I am an My name is Laura Donker, and I am an Earth Science major and a Biology Earth Science major and a Biology minor. I enjoy spending time minor. I enjoy spending time outdoors…especially in mountainous outdoors…especially in mountainous places, and yes – I do like looking at places, and yes – I do like looking at rocks! rocks!

One day, I plan to be a science teacher One day, I plan to be a science teacher at a middle or high school. I cannot at a middle or high school. I cannot wait to share everything I know with wait to share everything I know with my studentsmy students!!

Email me!Email me!

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ResourcesResources

Rock Cycle ImageRock Cycle Imagehttp://www.rocksandminerals4u.com/http://www.rocksandminerals4u.com/

All Rock ImagesAll Rock Imageshttp://geology.com/rocks/http://geology.com/rocks/

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