|
:''For the U.S.-based bank, see Ocean Bank'' An ocean bank, sometimes referred to as a fishing bank or simply bank, is a part of the sea which is shallow compared to its surrounding area, such as a shoal or the top of an underwater hill. Somewhat like continental slopes, ocean banks slopes can upwell as tidal and other flows intercept them, resulting sometimes in nutrient rich currents. Because of this, some large banks, such as Dogger Bank and the Grand Banks of Newfoundland, are among the richest fishing grounds in the world. There are some banks that were reported in the 19th century by navigators, such as Wachusett Reef, whose existence is doubtful. ==Types== Ocean banks may be of volcanic nature. Banks may be carbonate or terrigenous. In tropical areas some banks are submerged atolls. As they are not associated with any landmass, banks have no outside source of sediments. Carbonate banks are typically platforms, rising from the ocean depths, whereas terrigenous banks are elevated sedimentary deposits.〔Morelock, J. (2005). (Morphology ). Geological Oceanography Program, University of Puerto Rico at Mayagüez (UPRM). Retrieved on: October 11, 2008.〕 Seamounts, by contrast, are mountains, of volcanic origin, rising from the deep sea, and are steeper, and higher in comparison to the surrounding seabed.〔Farallones Marine Sanctuary Association. (Islands, Banks & Seamounts: Geologic Features Under the Sea ).〕 Examples are Pioneer and Guide Seamounts, west of the Farallon Islands. The Pioneer Seamount has a depth of 1,000 meters,〔 In other cases, parts of a bank may reach above the water surface, thereby forming islands.〔World Wildlife Fund. (Deep sea ecology: seamounts ). Retrieved on: October 11, 2008.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ocean bank」の詳細全文を読む スポンサード リンク
|