RocksGroup3

= = = ~Rocks~ =

 

Igneous Rocks

 * form when lava or magma cools and minerals crystallizes
 * the igneous rocks must be heated at a temperatures of 800 degrees C or 1200 degrees C.
 * they also are formed from a volcano if the cool quickly the rock will have a glass look to it.
 * the igneous are classified in 4 groups
 * intrusive rocks- are crystallized bellow the surface
 * extrusive rocks- magma that cools and crystals
 * basaltic rocks- dark color
 * granitic rocks- lighter color

<- the cooled fast thats why it has a glassy look

=Sedimentary Rock: =  Sediments are small pieces of rock that are moved and deposited by water, wind, glaciers and gravity. The formation of the rocks begins through the process of weathering and erosion. Weathering produces rock and mineral fragments. These rocks range in many different sizes.

One type of weathering is __** Chemical Weathering **__:

Chemical Weathering occurs when the minerals in a rock is dissolved or chemically changed. When chemically broken down the more grains are broken off the rock.



Another example is __**Physical Weathering**__ :

Physical Weathering is where the minerals remain the same.



The other part of sedimentary rocks is ** __Erosion__ : **

Erosion is the removal and transport of sediment rocks. The four main agents of Erosion are:


 * <span style="font-family: Tahoma,Geneva,sans-serif;">Wind
 * <span style="font-family: Tahoma,Geneva,sans-serif;">Moving Water
 * <span style="font-family: Tahoma,Geneva,sans-serif;">Gravity and
 * <span style="font-family: Tahoma,Geneva,sans-serif;">Glaciers

<span style="font-family: Tahoma,Geneva,sans-serif;">When rock fragments and sediments are weathered out of the rock they get moved onto different places/locations through the process of erosion. Eroded material is most likely always carried down-hill.

<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif;">

=<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif;">__Deposition__ : = <span style="color: #000000; font-family: Tahoma,Geneva,sans-serif;"> When transported sediments are deposited on the ground or sink to the bottom of a body of water, deposition occurs. They usually are Deposited when the transport stops.

= <span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif;">__Lithification__ : = = = <span style="font-family: Tahoma,Geneva,sans-serif;">As more sediments are deposited in an area, tthe bottom layers are subjected to increasing pressure and temperature. These are the Conditions of Lithification. Lithify comes from the Greek word lithos, which means stones.

=<span style="color: #ff0000; font-family: Tahoma,Geneva,sans-serif;">__Compaction__ :=

The weight of overlying sediments forces grains closer together. Groundwater, oil and natural gases are commonly found in these spaces in sedimentary rocks.

= =

= Metamorphic Rocks = <span style="font-family: Tahoma,Geneva,sans-serif; font-size: small; line-height: normal;"> Metamorphic rocks have been modified by heat, pressure and chemical process usually while buried deep below Earth's surface.

1) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12px; line-height: normal;">**<span style="font-family: Tahoma,Geneva,sans-serif; font-size: small; line-height: normal;">foliated metamorphic rocks ** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: small; line-height: normal;"> such as gneiss, phyllite, schist and slate which have a layered appearance that is made by exposure to heat and directed pressure. 2) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12px; line-height: normal;">**<span style="font-family: Tahoma,Geneva,sans-serif; font-size: small; line-height: normal;">non-foliated metamorphic rocks ** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: small; line-height: normal;"> such as marble and quartzite which do not have a layered appearance
 * There are two basic types of metamorphic rocks:


 * Metamorphic rock types; these include serpentinite, blue schist, soapstone and other rarer species such as eclogite.

- Serpentinite is a heavy, greenish metamorphic rock that forms by hydration.

-blue schist is high pressures combined with relatively low temperatures create a suite of blue minerals.

-soapstone is largely composed of the mineral talc and is rich in magnesium.

- eclogite is formed by regional metamorphosis of basalt under very high pressures and temperatures.
 * //*Fact: The oldest known rock lies in Canada. The Acasta gneiss, a metamorphic rock, is 3.96 billion years old// //.//

Metamorphic rocks changing cycle:** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 12px; line-height: normal;"> <span style="font-family: Helvetica,helvetica,sans-serif; font-size: 12px; line-height: normal;">


 * <span style="color: #0000cc; font-family: Tahoma,Geneva,sans-serif;">==Some Common Metamorphic Rocks== ||
 * ===Name=== || ===Image=== || ===Color=== || ===Texture=== ||
 * Gneiss || [[image:http://library.thinkquest.org/J002289/images/gneiss.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/gneiss.jpg"]] || Pink/Gray || Foliated ||
 * Marble || [[image:http://library.thinkquest.org/J002289/images/marble.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/marble.jpg"]] || Light Colored || Unfoliated ||
 * Quartzite || [[image:http://library.thinkquest.org/J002289/images/quartzite.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/quartzite.jpg"]] || Light Colored || Unfoliated ||
 * Slate || [[image:http://library.thinkquest.org/J002289/images/slate.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/slate.jpg"]] || Dark Gray to Black || Foliated ||

= Rock Cycle = <span style="font-family: Verdana,Arial,sans-serif; font-size: 12px; line-height: normal;">A way to illustrate how the three main types of rock are related to one another and how changes to rocks happen in a sequence is the rock cycle.

//__How the rock cycle works:__// <span style="font-family: Tahoma,Geneva,sans-serif; font-size: small;">*First, Start at is the magma chamber.


 * Next, the igneous rocks erode and turn into sediments. The sediments go through years of pressure and cementation which turns the sediments into sedimentary rock layers.

<span style="font-family: Tahoma,Geneva,sans-serif; font-size: small;">*Again the rocks go through heat and pressure and turn into metamorphic rocks like at the start. Then the new metamorphic rocks go through heat and turn into magma.

Link to show how the rock Cycle Works:** <span style="font-family: Helvetica,Arial,sans-serif; font-size: 13px; line-height: 19px;">http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm

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