- Slides: 11
The Ocean Floor
Features of the Ocean Floor
Continental Shelf �Zone of shallow water where the ocean covers the end of the continent. �Shallow slope �Where most ocean life is found. Why? �Answer: Photic zone is the first 100 feet of water and allows sunlight to penetrate the water.
Continental Slope �Continental slope is a very steep slope off the continental shelf. �Here, the ocean becomes very deep. �Submarine canyons are carved out by underwater landslides called turbidity currents.
Continental Rise �Sediments from the submarine canyons are deposited further out in the ocean. �These sediments form the continental rise. �It is here that the continental crust ends and oceanic crust begins.
Abyssal Plain • A large, flat, almost level area of the deep-ocean basin �Abyssal plains cover about half of the deepocean basins and are the flattest regions on Earth. �Layers of fine sediment cover the abyssal plains.
Mid-Ocean Ridge �Formed by divergent plate boundary. �Magma rises as plates pushed apart. �Forms underwater mountain range of volcanoes. �These ridges can cause sea level to rise and fall drastically.
Guyots and Seamounts �Guyot: A flat-topped underwater mountain. Formerly an island that was eroded and sank into the ocean. �Seamounts: Pointedtopped underwater mountain ranges that were likely volcanic. �Hawaii will become seamounts and guyots.
Trenches �Deepest point in the ocean. �Have the most pressure. �Formed from convergent boundaries where one plate dives beneath another (Subduction zone). �Often form Island Arcs like Japan or Philippines.
Ocean Floor Sediments
Sediments �Clastics: Sand, silt, mud, and clay found on continental shelf make up the thickest sediments. �Biogenic Sediments: Calcium carbonate and Silica from organisms like forams and diatoms leave oozes on the ocean floor that form Chert (Silica from diatoms) and Chalk (Calcite from forams). Also limestone (calcite). �Chemical Sediments: Nodules of manganese, copper, iron, and nickel can form and be found scattered on the ocean floor.