The vast give-and-take at the Earth- atmosphere-ocean interface or cycling within the lithosphere –Fueled by the sun and Earth’s internal heat –Hydrologic Cycle –Rock Cycle –Tectonic Cycle The Geologic Cycle
Extrusive Igneous Rock Basalt - fine-grained, dark-colored extrusive igneous rock Rhyolite - fine- grained, dark-colored extrusive igneous rock
Intrusive Igneous Rocks Diorite – coarse-grained, intrusive igneous rock Gabbro – coarse-grained, intrusive igneous rock Granite – coarse-grained, intrusive igneous rock
Sedimentary Rock Vast amts of formerly loose minerals (sediment) deposited in layers Sediments cement to each other in process called lithification – 3 Types:
Clastic Sedimentary Rock Examples Siltstone Sandstone
Chemical Sedimentary Rock Formation Andros Island, Bahamas
Chemical Sedimentary Rock Examples Limestone - can also form chemically from the precipitation of calcium carbonate from lake or ocean water Rock Salt - forms from the evaporation of ocean or saline lake waters.
Organic Sedimentary Rocks Coal – from plant and organic matter deposited in cool wetlands, forming peat – over time overlying layers of sediment compress & heat peat into coal “Overcooked” deposits become petroleum Natural gas – from microscopic plants at surface of sea water – decompose to gas
Metamorphic Rocks From igneous & sedimentary rock under great heat & pressure for millions of years Examples of igneous & sedimentary rocks becoming metamorphic: –Shale → Slate → Schist –Limestone → Marble –Sandstone → Quartzite
Metamorphic Rock Examples Schist Slate Marble Quartzite
Geologic Time Earth’s history (4.5 B years) divided into: –Eons Eras –Periods »Epochs Radiometric Dating – compare amt of radio- active isotope to amt of decayed end product in a rock to estimate its age
Geomorphology of Continents and Ocean Basins Geomorphology – study of formation, shape, distribution, & evolution of landforms on Earth Landform – a distinct geographic feature such as a mountain, river valley, coastline, or sand dune Continents consist of 3 basic geomorphic regions: Alpine Chains, Continental Shelves, & Continental Shields
Continental Shelf Earth’s land area increases dramatically (from 29% to 35% of Earth’s surface) if sea level falls as in a previous glaciation (1.6 my ago) because of the relatively shallow continental shelf.
Continental Shields Geologically inactive regions with low relief made of old, stable, igneous or metamorphic rock
Alpine Chains Belts of active mountain building due to volcanic or tectonic processes