GEOS 1004 Lecture Notes - Lecture 18: Abyssal Plain, Continental Crust, Geochemistry
Document Summary
The oceans are critical for earth surface processes: the largest reservoir of water, control climate, influence surface geochemistry, a hazard, a resource, ocean physiography. The sea floor and geography of oceans are controlled by plate tectonics. Mid-ocean ridges and trenches occur at the plate boundaries. In between, most sea floor is ~5 km deep; the flat abyssal plain. Sediments of the abyssal plain are fine clay and chert. Rising from the abyssal plain is the gentle (~5 ) continental slope. Sediment is controlled by underwater landslides of mixed sand and mud (turbidity currents). Above the slope is the continental shelf, lying above thin continental crust. 200 m deep and dominated by thick sand/mud from rivers (+/- carbonate): ocean movement. Solar insolation (radiative heating) varies with latitude; this uneven distribution of thermal energy drives ___________________________ of the oceans. Water that is more saline (due to evaporation) sinks, whereas fresher water (e. g. meltwater from ice) is less dense and floats.
