Structure of the earth – Core Inner: solid, high temp and pressure, made of: nickel and iron Outer: liquid, cooler than the inner core, Made of: nickel and iron – Mantle Made of iron, oxygen and silicon (Rock called peridotite) Solid at the bottom becomes more Pliable and plastic near the surface. Upper layers: asthenosphere and the lithosphere – Crust Thinnest zone (6 miles deep to 35 miles deep) Mostly made of silicon and oxygen in the Form of quartz (SiO2) Two types of crust: - oceanic-which is dense and made of basalt - continental crust Which is less dense and made of: granite

Geologic Processes  Structure of the Earth Mantle Core Crust Low-velocity zone Solid Outer core (liquid) Inner core (solid) 35 km (21 mi.) avg., 1,200˚C 2,900km (1,800 mi.) 3,700˚C 5,200 km (3,100 mi.), 4,300˚C 10 to 65km 100 km 200 km 100 km (60 mi.) 200 km (120 mi.) Crust Lithosphere Asthenosphere (depth unknown) Fig. 10.2, p. 212

Internal Earth Processes Plate tectonics: theory developed in the 1960’s about the crust of the earth. The theory says that the crust is not one large piece, but is broken into large segments called plates. When these plates move and collide they form:

Divergent Plate Boundary Divergent plate boundary: where plates move apart in opposite directions Landforms: under water mountain chains called mid-ocean ridges, on land forms rift valleys Examples: Mid-Atlantic Ridge, African Rift Valley, Iceland, Baja California

Convergent Plate Boundaries Convergent plate boundary: Where plates collide Forms subduction zones where one plate rides up and over the other plate, this causes deep-sea trenches, and steep sided composite cone volcanoes. This only occurs where continental crust collides with oceanic crust or where oceanic crust collides with continental crust. Continental crust can collide with continental crust and form folded mountains. Examples: Mt. Everest, Mt. St. Helens, Mt. Fuji, Mt. Vesuvius

Continental VS Continental

Continental VS Oceanic

Oceanic Vs. Oceanic

Transform Boundaries Transform Boundary: plates slide past one another in opposite, but parallel directions. Examples: San Andreas Fault

Transform

California Geology

External Earth Processes – Weathering: Breaking down rock into smaller pieces Mechanical weathering: roots, animals, freeze-thaw: Chemical: lichens, organic acids, acid rain and: – Erosion: Picking up small rocks and carrying them away Wind: desert pavement, san dunes, abrasion Water: beaches, levees, oxbow lakes, meanders Ice: glaciers – Kettle lakes, moraine, till, u-shaped valleys, hornstill Gravity: Mudslides, landslides