Transcript Rocks
Rocks Sedimentary, Metamorphic, Igneous Sedimentary Rock Sedimentary Rock • Weather break rocks into small pieces that are carried away and left elsewhere. • These small pieces are often left in shallow seas or lakes. • As the layers pile up, perhaps over millions of years, pressure from the weight of the sediments above turns the lower layers into solid rock. • Sand may turn into sandstone; silt and clay become shale. Such rock, made of sediment, is called sedimentary rock. Sedimentary Rocks Sandstone: Made from sand cemented together Limestone: Made from shells of dead sea animals Shale: Made from mud cemented together Chalk: Made from shells of dead sea animals Igneous Rock • The inside of the earth is very hot - hot enough to melt rocks. • The deeper you get the hotter it gets. • As the super hot magma cools, it solidifies to form a rock and that rock is called igneous rock. When most people think of igneous rock they vision a volcano erupting. • Igneous rocks crystalize after the magma reaches the earth's surface. Igneous Rock • Igneous rock is divided into 2 groups: – Extrusive - when magma flows onto the surface of the earth or floor of the ocean through deep cracks and at volcanic vents, and then cools and hardens. – Intrusive- when magma solidifies beneath the earth's surface and is later found in mines and tunnels or at the surface where it has been exposed by the ground shifting and by erosion. Igneous Rock Granite: Made from magma inside the Earth Rhyolite: Made from lava on the surface of the Earth Basalt: Made from lava on the surface of the Earth Metamorphic Rock • Metamorphic rock is rock that has been altered by heat or by heat and pressure. • ‘Metamorphic' means ‘change of form'; • Rocks change when mountain-building forces apply a great deal of pressure and heat to them. • Rock is changed by heat produced by nearby molten rock, or by both heat and pressure produced mainly by movements in the earth's surface. • Metamorphic rocks are sedimentary or igneous rocks that have been modified or changed in form Metamorphic • No banding- usually rock of one mineral • Example: Quartzite (from sandstone quartz) • Example: Marble (from limestone calcium carbonate) Metamorphic • Types • banded • Example: Schist (fine grain) (from slate) • Example: Gneiss (coarse grain) (from a variety of rock, one of which is granite)