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TOPOGRAPHY OF THE SEAFLOOR NOTES. Area of the continent (land) that is underwater. Area that has been flooded and covered with water over many years. This is made up of continental crust (mainly granite). The east coast’s original shoreline used to be 70 miles further out to sea.
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Area of the continent (land) that is underwater. Area that has been flooded and covered with water over many years. This is made up of continental crust (mainly granite). The east coast’s original shoreline used to be 70 miles further out to sea. CONTINENTAL MARGIN
Continental Shelf Continental Slope Continental Rise Submarine Canyon FEATURES FOUND ON CONTINENTAL MARGIN:
Gently sloping part of the continent that is underwater. Used by nations as a legal boundary. The east coast’s shelf is a lot larger than the west coast’s shorter shelf. CONTINENTAL SHELF
The steep sloping edge of the continent that extends from the edge of the shelf to the ocean floor. CONTINENTAL SLOPE
A mound of sediments that separates the continental slope from the ocean bottom. The sediments found here is terrigenous (found from land), but the floor here is made of basalt (ocean floor). CONTINENTAL RISE
Canyon carved out of the continental shelf. Typically runs perpendicular to the shoreline. Carved out by water (typically rivers). Remember the continental shelf used to be “land.” SubmarinE Canyon
The part of the ocean that is oceanic crust. Made primarily of basalt. OCEAN BASIN
Abyssal Plain Mid-Ocean Ridges Rift Valley Seamounts Guyots Atoll Trenches FEATURES FOUND ON CONTINENTAL MARGIN:
Very flat area of the ocean floor at the edge of the continental rise. ABYSSAL PLAIN
Long, underwater mountain chains. These are associated with spreading centers (divergent plate boundaries). New seafloor is being formed here. MID-OCEAN RIDGES
A deep valley which runs down the center of a mid-ocean ridge. Magma oozes out of these valleys which harden into new seafloor. RIFT VALLEY
Underwater mountains, usually volcanic. The biggest mountain on earth is Mauna Loa (Hawaii). Seamounts build-up over time underwater (usually over a hot spot) and eventually break the surface of the water. Seamounts above water turn into islands. When they move away from the hot spot, the seamount will start to “deflate” and go back underwater. SEAMOUNTS
After the seamount becomes an island, coral reefs typically form around the island. The point in which the island subsides back underwater, and the coral reef is still in tact, it becomes an atoll. atolls
Flat-topped seamounts, formed from being above sea level at one time. When seamounts are above water, they experience a lot of weathering and get worn-down and flatten out over time. Guyots are the “deflated” seamounts that have subsided back underwater (the coral reef is no longer present). GUYOTS
A long, narrow, deep depression of the sea floor with steep sides. These are the deepest places on Earth. NOT associated with mid-ocean ridges. Typically formed from earthquakes and tectonic activity. TRENCHES