By Marissa Welch

EDU 290

Central Michigan University

Rocks

A Rock is a grouping of one or more mineralsThree types

Igneous Sedimentary Metamorphic

What is a rock?

Rocks are very useful in the environment for things such as:cement, gravel, building materials, countertops, tiles, and statues as well as other things like containing ground water and oils/gasHelps to discover the history of the Earth’s atmosphere and life on Earth

Why study Rocks?

Igneous rocks are formed by cooling and crystallization of magma (below the Earth’s surface) or Lava (above the Earth’s surface)

There are two types of Igneous rocksIntrusive which form from magma coming up

from the mantle into the crust and coolingExtrusive which form from volcanic eruptions

Igneous Rocks

Examples of Igneous RocksGranite is an example of an

Intrusive Igneous Rock It forms under the Earths

surface from the cooling of magma leaking up from the mantle of Earth

Intrusive igneous rocks have noticeably large crystals and are usually rough to the touch unless they are polished Examples: Kitchen Counters

The Continental Crust of the Earth is primarily made of Granite

Other examples of Intrusive Igneous Rocks:

Gabbro Andesite Diorite

Examples of Extrusive Igneous RocksBasalt is an example

of an Extrusive Igneous Rock

The Oceanic Crust is made primarily of Basalt Basalt is formed

from lava on the crust of the Earth.

Because it is formed on the surface, the crystals are very fine-grained

Obsidian Rhyolite Scoria

Other examples of Extrusive Igneous Rocks

Sedimentary RocksSedimentary rocks are formed by the

accumulation of sediments. Sediments include materials from sand grain

size to boulder size There are three basic types of sedimentary

rocks:Clastic (physical weathering)Chemical Organic

Clastic Sedimentary RocksClastic Sedimentary

Rocks are formed from mechanical weathering debris

Mechanical weathering takes place when rocks are broken down without any change in the chemical nature of the rocks

breccia, conglomerate, sandstone and shale are some examples

Breccia

Conglomerate

Sandstone

Shale

Chemical Sedimentary RocksChemical

Sedimentary Rocks form when dissolved materials precipitate from solutionExample : Halite that

forms from dried up saltwater lakes

rock salt (Halite) and some limestone are examples of Chemical Sed. Rocks

Halite

Limestone

Organic Sedimentary RocksOrganic Sedimentary

Rocks form from the dead plants and animals and their debris.

Coal and fossiliferous limestone are examples of organic sed. rock An example of

fossiliferous limestone has sea shells in it

Organic material comes from anything living or has lived before

Fossiliferous Limestone

Coal

Metamorphic RocksMetamorphic rocks have been modified by

heat, pressure and chemical process usually while buried deep below Earth's

surface.Exposure to these extreme conditions has

altered the minerals, texture and chemical composition of the rocks.

There are two basic types of metamorphic rocks:

Non-foliated Foliated

Foliated Metamorphic RocksFoliated

metamorphic rocks: have a layered or banded appearance known as a foliation

Examples are gneiss, phyllite, schist and slateproduced by

exposure to heat and directed pressure

Gneiss

Schist Slate

Non-Foliated Metamorphic RockNon-foliated

metamorphic rocks such as marble and quartzite

do not have a layered or banded appearance

Quartzite

Marble

All pictures came from www.gelogy.comInformation on definitions came from the

book used in Gel 100 at Central Michigan University

Information from slides 9-15 came from www.gelogy.com Sedimentary information came from http://

geology.com/rocks/sedimentary-rocks.shtml Metamorphic information came from http://

geology.com/rocks/metamorphic-rocks.shtml

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