Presentation on theme: "Rocks. Different from minerals Can be organic Classified by: –C–C–C–Color –T–T–T–Texture –M–M–M–Mineral composition –O–O–O–Origin (how they were formed)."— Presentation transcript:
Different from minerals Can be organic Classified by: –C–C–C–Color –T–T–T–Texture –M–M–M–Mineral composition –O–O–O–Origin (how they were formed). Three main groups of rocks.
Igneous Rocks Formed by cooled magma or lava. Found in volcanic regions 2 types: –I–I–I–Intrusive: Rocks that cool under Earth’s surface. CCCCool slowly. –G–G–G–Grains of rock are bigger –E–E–E–Extrusive: Rocks that cool on Earth’s surface. CCCCool quickly. –G–G–G–Grains of rock are smaller, with more air spaces (pores)
Sedimentary Rocks 5 step process creates sedimentary rocks Weathering: Existing rock is broken down into sediments. Erosion: Sediments are carried away to a new location Deposition: Sediments are laid down in a new location. Build up in layers. Compaction: Sediments are pressed together by the wieght of new sediment on top. Cementation: Sediments are glued together by a chemical reaction.
Sedimentary Rocks cont. Usually seen in layers. Fossils are found only in sedimentary rocks.
Examples Sandstone Shale Limestone Conglomerate
Metamorphic Rocks Formed by heat and pressure acting on existing rocks. Sandstone (heat & pressure) Quartzite