Rock Review

Major Rock Groups:

-Igneous: Forms when molten rock (lava/magma) cools and solidifies; categorized by grain size and mineral content.

-Grain size:

-Intrusive: Formed beneath Earth's surface+slow cooling=LARGE grains

-Extrusive: Formed at/near Earth's surface (often associated with volcanic activity) + rapid cooling=SMALL grains

 -Mineral content:

-Felsic: Lightly colored; Al and Si rich.

 -Mafic: Dark in color; Fe and Mg rich.

-Sedimentary: Forms by the compaction and cementing of layers of sediment.

 -3 Types:

-Clastic or Terrigenous (sediment)

-Biogenic (contains fossils, shells; once living things)

-Chemical (precipitation, evaporation; chemical reactions)

 -Proccess:

1. Weathering- decays and breaks up rock

2. Erosion- soil and rock are loosened and moved

3. Transportation- movement of sediment by water or air

4. Deposition- settles out into flat/horizontal layers

5. Lithification- compacts and cements; hardens into solid rock

-Metamorphic: Forms when igneous, sedimentary, or other metamorphic rocks change into other rocks by heat and/or pressure without actually melting.

 -Causes:

-Heat

-Pressure

-Chemically active fluids

 -Location: ALWAYS located on the interior of the Earth

  -Proccesses:

-Compaction- moves grains closer together

-Chemical recrystallization- the formation and growth of new crystals

 -Texture:

-Foliated- bands circling the outside of the rock

-Non-foliated- no (visible) bands