RocksGroup2

-One of the three main rock types. -Igneous rock is formed by magma being cooled and becoming solid. - melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. -i gneous rocks make up approximately 90% of the upper part of the Earth's crust -they are the oldest type of rock. The word igneous comes from the greek word for fire. - Igneous rocks are classified according to mode of occurrence, texture, mineralogy, chemical composition, and the geometry of the igneous body. - The slow cooling formed rocks with large [|crystals] . Granite is an example of a rock that cooled slowly and has large crystals. - Igneous rocks form in three main places: where lithospheric plates pull apart at mid-ocean ridges, where plates come together at subduction zones and where continental crust is pushed together, making it thicker and allowing it to heat to melting.
 * IGNEOUS ROCKS

WHERE IGNEOUS FORM: Igneous rocks form in three main places: where lithospheric plates pull apart at mid-ocean ridges. where plates come together at subduction zones. where continental crust is pushed together, making it thicker and allowing it to heat to melting.

TYPES:

Intrusive- -when they form below the earths surface. -coarse grained -magma cools slowly

Extrusive- - when they form on the earths surface. - fined grained - magma cools quickly   

PICTURES: **


 * ||||||||~ Composition ||
 * ~ Mode of occurrence || Felsic || Intermediate || Mafic || Ultramafic ||
 * Intrusive || [|Granite] || [|Diorite] || [|Gabbro] || [|Peridotite] ||
 * Extrusive || [|Rhyolite] || [|Andesite] || [|Basalt] || [|Komatiite] ||
 * ||||||||~ Essential rock forming silicates ||
 * ~  || Felsic || Intermediate || Mafic || Ultramafic ||
 * Coarse Grained || [|Granite] || [|Diorite] || [|Gabbro] || [|Peridotite] ||
 * Medium Grained ||  ||   || [|Diabase] ||   ||
 * Fine Grained || [|Rhyolite] || [|Andesite] || [|Basalt] || [|Komatiite] ||

 
 * **==Some Common Igneous Rocks==** ||
 * **===Name===** || **===Image===** || **===Color===** || **===Texture===** ||
 * **Granite** || [[image:http://library.thinkquest.org/J002289/images/granite.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/granite.jpg"]] || **Pink/Gray** || **Intrusive** ||
 * **Gabbro** || [[image:http://library.thinkquest.org/J002289/images/gabbro.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/gabbro.jpg"]] || **Dark Gray to Black** || **Intrusive** ||
 * **Rhyolite** || [[image:http://library.thinkquest.org/J002289/images/rhyolite.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/rhyolite.jpg"]] || **Light Pink or Gray** || **Extrusive** ||
 * **Basalt** || [[image:http://library.thinkquest.org/J002289/images/basalt.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/basalt.jpg"]] || **Dark Gray to Black** || **Extrusive** ||
 * **Obsidian** || [[image:http://library.thinkquest.org/J002289/images/obsidian.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/obsidian.jpg"]] || **Usually Dark Colored** || **Extrusive** ||
 * **Scoria** || [[image:http://library.thinkquest.org/J002289/images/scoria.jpg width="75" height="75" align="center" link="http://library.thinkquest.org/J002289/images/scoria.jpg"]] || **Dark Colored** || **Extrusive** ||



** WEBSITES:

http://en.wikipedia.org/wiki/Igneous_rocks

SEDIMENTARY ROCKS **** Vocabulary: sediments - small pieces of rock that are moved and deposited by water, wind, glaciers, and gravity. lithification - the physical and chemical processes that transform sediments into sedimentary rocks. ( lithy comes from the Greek word lithos, which means stone.) cementation - occurs when mineral growth glues sediment grains together into solid rock. bedding - the primary feature of sedimentary rocks horizontal layering. graded bedding - bedding in which the particle sizes become progressively heavier and coarser toward the bottom layers. cross bedding - formed as inclined layers of sediment are deposited across a horizontal surface, erosion - the removal and transport of sediment Facts: -The formation of sedimentary rocks begins when wea thering and erosion produce sediments. ** -Chemical weathering occurs when the minerals in a rock are dissolved or otherwise chemically changed. -When less stable minerals are chemically broken down, the more-resistant grains are broken off of the rock as smaller grains. -After rock fragments and sediments have been weathered out of the rock, they often transported to new locations through the process of erosion.
 * -Sediments range in size from huge boulders to microscopic particles.

PICTURES: **



**- heat and pressure creats metamorphic rocks - goes through physical and chemical changes - formed deep in the Earths crust - make up a huge part of the Earths crust - examples of metamorphic rocks are: gneiss, slate, marble, schist, and quartzite - layering in a metamorphic rock is called foliation - when a rock is not layerd it is nonfloliated - metamorphic rocks have a grain size anywhere from fine to coarse - the texture in metamorphic rocks are banding and mineral alignment - regional, is a type of metamorphism which is wen the heat and pressure increase**
 * METAMORPHIC ROCKS **


 * PICTURES:**



- the rock cycle describes the transistions threw the three rock types, igneous, sedimentary, and metamorphic ** - **the rock cycle is an illustration that explains how the 3 rock types are related to each other and how processes change from one type to another over time**
 * ROCK CYCLE:**

PCITURES:

the rock cycle igneous rock formation