The Rock Cycle The processes through which rocks are formed

Igneous Rocks  Form by the cooling of molten rock (either lava or magma)  Typically have a texture of random crystals  Form by the cooling of molten rock (either lava or magma)  Typically have a texture of random crystals

Iceland s, Alan Rubin

Eruption of Mount St. Helens - May, 1980 (commercial slide)

Mount St. Helens

Middle and North Sister - Oregon Cascades

Sedimentary Rocks  Often form when particles weathered from earlier rocks are transported (by streams, wind or glaciers) and deposited as sediment  The sediment is then buried and converted to rock by compression and cementation  Typically have a texture of small rounded particles cemented together  Often form when particles weathered from earlier rocks are transported (by streams, wind or glaciers) and deposited as sediment  The sediment is then buried and converted to rock by compression and cementation  Typically have a texture of small rounded particles cemented together

French Pete Creek - Oregon Cascades

Basin and Range - eastern Nevada

Cochetopa Creek near Gunnison, Colorado

Creek building delta into Lyman Lake - Washington Cascades

Cape Cod, Massachusetts

Canyonlands National Park, UT - Needles section

Metamorphic Rocks  Generally form when earlier rocks are subjected to high temperatures and/or pressures (BUT without melting!)  Typically have a crystalline texture, with a pattern to the arrangement of crystals  Generally form when earlier rocks are subjected to high temperatures and/or pressures (BUT without melting!)  Typically have a crystalline texture, with a pattern to the arrangement of crystals

Mt. Jefferson, Oregon Cascades