14-2 Flashcards
what are the ocean floor regions?
continental margins, ocean basin floor, and mid-ocean ridges
what are continental margins?
area of transition between a continent and adjacent ocean basin floor. Atlantic Ocean: thick undisturbed sediment covering, not associated with plate boundaries
Pacific Ocean: subduction zones, lot of volcanoes and earthquakes, narrow
what is a continental shelf?
lies beyond every shoreline, under ocean water, relatively flat part of the continent with a gentle slope.
what is a continental slope?
starts at end of continental shelf, steeper, boundary between continental and oceanic crust. relatively narrow
what is a submarine canyon?
steep-sided valleys cut into continental slope, may extend to ocean basin floor
what are turbidity currents?
occasional movements of dense, sidemeat-rich water down the continental shelf, currents erode and form submarine canyons, may be triggered by earthquakes
what is continental rise?
in areas of no trenches, steep continental slope merges into a more gradual incline. Thick layer of sediments that moved from the shelf to deep ocean, more steep than continental shelf but less steep than continental slope.
what is ocean basin floor?
between continental margin and mid-ocean ridge. large area, consists of four major features
what are the four major features of the ocean basin floor?
abyssal plains, deep-ocean trenches, seamounts, and guyots
what are abyssal plains?
extremely flat and deep areas.
Currents deposit sediments from land and continental shelf and elopes onto ocean floor and deposits sediments filling in valleys which creates thick accumulation of fine sediment
what are deep-ocean trenches?
long steep-sided depressions in the ocean floor
One plate going under another plate, causes earthquakes and volcanoes. mariana trench
what are seamounts?
volcanic peaks not tall enough to break through ocean surface, steep-sided like volcanoes on land, some form hotspots
what are guyots?
results from volcanic island that erodes away by running water or waves. Islands may slowly sink as plates move them away from elevated areas, once island is submerged then a guyot
what are mid-ocean ridges?
where new ocean floor forms. forces within Earth spread seafloor apart, causing seafloor to buckle up making a ridge on both sides. longest topographic feature
what is seafloor spreading?
diverging plates moving away from each other, new crust forms
