17.1 Notes: Earth’s Mantle & Crust

Continental crustThickness: Continental crust is thicker (30-40Km)

Age: older (up to 4.4 billion yrs old)

Composition: Granite, w/ basalt & diorite beneath

Density: Less dense

Oceanic Crust

Thickness: Thinner (6-11km)

Age: younger (200 million yrs old)

Composition: basalt gabbro

Density: more dense

Moho (Mohorovičić discontinuity) Structure: a low pressure & temperature region, so rock becomes more rigid & slows down seismic waves.

Upper Mantle

Structure: Thin top section w/ extreme pressures. Pressures & temperature increase with depth.

Lower mantle

Structure: Bottom section has a higher temperature & pressure than upper mantle

Describe movement between lower & upper mantle:Rock isn’t quite solid here so it moves like a very thick liquid (due to convection).