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 ProcessesGeologic ProcessesGeologic ProcessesGeologic Processes

Structure ofthe Earth

Structure ofthe Earth

Mantle

Core

Crust

Low-velocity zone

Solid

Outer core(liquid)

Innercore(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 ProcessesPlate 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 BoundariesConvergent 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,

horns• Gravity: Mudslides, landslides