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Cordell Bank National Marine Sanctuary is a marine sanctuary located off the coast of California. It protects an area of of marine wildlife. The administrative center of the sanctuary is on an offshore granite outcrop by , located on the continental shelf off of California. The outcrop is, at its closest (Point Reyes), from the sanctuary itself.〔(【引用サイトリンク】title=About the Sanctuary )〕 Cordell Bank is one of the United States' 13 National Marine Sanctuaries that protect and preserve ocean ecosystems in the U.S. Cordell Bank is a seamount approximately northwest of San Francisco where the ocean bottom rises to within 120 feet (37 meters) of the surface. The seamount was discovered in 1853 by the U.S. Coast Survey, and named for Edward Cordell, who surveyed the area more thoroughly in 1869. It was extensively explored and described during 1978-86 by Robert Schmieder, who published a monograph about it (1991 ). It has been protected as a sanctuary since 1989. The protected area encompasses 526 square miles (1347 km2) of ocean. The unique blend of ocean conditions and undersea topography creates a rich and diverse underwater ecosystem. A subsurface island rises from soft sediments covering the continental shelf. The upper pinnacles reach to within of the surface, and the average depth is . The sanctuary serves as a breeding ground for migratory marine mammals, birds, and fish. The prevailing California Current flows southward along to coast, causing an upwelling of nutrient-rich water that provided the foundation for the area's marine ecosystem.〔 Sanctuary regulations prohibit extraction of hydrocarbons (oil, natural gas), the removal of benthic (bottom-dwelling) organisms, discharge of wastes, and removal of cultural resources. Recreational scuba diving is not recommended in the sanctuary due to depth and currents. ==Geological setting== Cordell Bank was originally created 93 million years ago, as a member of the Sierra Nevada. The grinding of the plates at the San Andreas Fault, with the Pacific Plate moving north and the North American Plate moving south, parts of the Sierra Mountains were sheared off and carried northwards, including Cordell Bank. Eventually this grinding carried Cordell Bank to its present location opposite Reyes Point. Cordell Bank is still moving, by an average of per year.〔(【引用サイトリンク】title=Natural Natural Environment: Geologic History )〕 Between 20,000 and 15,000 years ago the sea level in the area was below the current level, leaving most of Cordell Bank exposed and making it a true island. Today the bank rises out of soft sediment, deposited on the bank more recently by coastal erosion. Within just of Cordell Bank, the continental shelf drops to over deep.〔 The seamount is largely composed of granite. 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「Cordell Bank National Marine Sanctuary」の詳細全文を読む スポンサード リンク
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