Rocks
I. Classifications
A. Igneous
B. Sedimentary
C. Metamorphic
II. Igneous rocks are formed when magma cools
A. Extrusive rock is pushed out onto earth's surface as lava
1. Obsidian
2. Pumice
3. Basalt
B. Intrusive rock is under the earth's surface
1. Granites
2. Syenites
III. Sedimentary rocks are made of strata
A. Clastic sediments are made from rock material
1. Shale
2. Sandstone
3. Conglomerate rock
B. Chemical sediments are made from dissolved minerals
1. Rock salt
2. Phosphate rock
3. Gypsum
4. Some limestone
C. Organic sediments are made from plant and animal material
1. Coal
2. Chalky limestone
IV. Metamorphic rock is rock that has been changed by forces
A. Can be changed from both igneous and sedimentary rocks
1. Granite becomes gneiss
2. Limestone becomes marble
3. Sandstone becomes quartzite
4. Shale becomes slate