Elizabeth Riker, Aaron Mosesso, Mike Werhan, and Abbi Smith

Rocks

Classifications of Rocks

Sedimentary RockSediment rocks occur

by weathering, erosion and transport because of wind and water, sediments become rock when they get compacted.

Common sedimentary rocks are:LimestoneSandstoneConglomerate

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:GraniteBasalt Diorite

Granite

Metamorphic RocksMetamorphic 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: GneissSchistSlate

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 orock layers were depositedin a horizontal orientation.

•If units aren’t horizontalan event occurredsubsequent to thedeposition whichcaused layers to fold ortilt.

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.