Rocks Elizabeth Riker Aaron Mosesso Mike Werhan and
Rocks Elizabeth Riker, Aaron Mosesso, Mike Werhan, and Abbi Smith
Classifications of Rocks
Sedimentary Rock Sediment rocks occur by weathering, erosion and transport because of wind and water, sediments become rock when they get compacted. Common sedimentary rocks are: Limestone Sandstone Conglomerate
Igneous Rocks The Earth has magma deep inside it. If the magma stays underground, cools, and hardens, it makes intrusive igneous rock. Extrusive igneous rock is made when magma comes to the Earth’s surface in the form of lava and then cools and hardens. Common igneous rocks are: Granite Basalt Diorite Granite
Metamorphic Rocks Metamorphic rocks are formed when other kinds of rocks are changed by great heat and pressure inside the earth. They were once indigenous or sedimentary rocks but have morphed over time. They are usually toward the bottom of layers of rocks. Common Metamorphic rocks are: Gneiss Schist Slate Gniess
Stratigraphic Laws
Law of Superposition • States that the oldest layer of rock is at the bottom and the youngest layer of rock is at the top.
Law of Original Horizontality • States that sediment o rock layers were deposited in a horizontal orientation. • If units aren’t horizontal an event occurred subsequent to the deposition which caused layers to fold or tilt.
Law of Lateral Continuity • States that deposits originally extended in all directions.
Law of Cross-Cutting Relationships • States the relationship between existing rock and rock which intrudes by magma flow into existing rock. • This creates and intrusion and an intrusion is always younger than the rock it invades.
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