ROCKS
Definition: A rock is a mixture of minerals
Igneous Rocks Igneous rocks are formed as lava or magma cools.
a) Intrusive If the magma cools slowly beneath the surface, INTRUSIVE rocks result INtrusive rocks form INside the Earth and have large crystals since there is time for them to form.
b) Extrusive If the lava cools quickly on the surface EXTRUSIVE rocks result. EXtrusive rocks have EXited the Earth and have small crystals since they formed so fast.
Other igneous rocks…. Diorite and Pumice
Sedimentary Rock Sedimentary Rock is made of sediment that has been compacted and/or cemented together. Delicate Arch in Arches National Park
Sedimentary Facts: 75% of the Earth’s surface rock is sedimentary. Sedimentary rocks store ground water, oil, and coal.
Clastic Sedimentary rock is made of fragments of other rocks.
Organic sedimentary rock has traces of once living things in the rock.
Chemical sedimentary rocks are formed when minerals crystallize as a solution dissolves First image is a playa lake in California in the process of drying up – the evaporates are visible in a ring The second picture is dripping calcium and carbonate bonding together to form calcite in Carlsbad Caverns
Sedimentary rock is held together by COMPACTION and/or CEMENTATION:
During compaction, rocks are squeezed together because of a lot of pressure from above.
During cementation, rocks are held together by a mineral ‘glue’ During cementation, rocks are held together by a mineral ‘glue’. Minerals fill in the spaces between the sediments and bind them together forming a solid rock.
Metamorphic Rock Metamorphic rock is rock that has been changed due to heat and/or pressure. Anticline and syncline in Canadian Rockies. May be sed. .rock and not metamorphic, but an example of stresses of the Earth on rock to make metamorphic. Small dark things are trees.
Foliated metamorphic rock has bands of colors through it Gneiss
Non-foliated metamorphic rock does not have bands of color. Marble
Rock Cycle – any rock can become another rock