Pioneer Seamount
Encyclopedia
Pioneer Seamount is an undersea mountain
, or seamount
, in the Pacific Ocean
off the coast of central California
.
, 123° 26.1' West Longitude
, at the base of the continental slope of North America
about 95 kilometers (51 nautical miles) off the coast just north of San Francisco
, California.
between 10.9 and 11.1 million years old. It is about 12.8 kilometers (6.9 nautical miles) long as well as about 12.8 kilometers (6.9 nautical miles) wide, and has a volume of about 135 cubic kilometers (32.4 cubic miles). It rises about 1,930 meters (6,332 feet) above the surrounding ocean floor, and its peak is a minimum of 820 meters (2,696 feet) below the oceans surface. Samples from the seamount consist of highly vesicular alkalic basalt
, hawaiite
, and mugearite
.
s dominate in deeper areas and sponges in its shallower parts.
, the first of three survey ships of the United States Coast and Geodetic Survey to bear the name. Pioneer operated along the United States West Coast and in the then-Territory of Alaska during her Coast and Geodetic Survey career, which lasted from 1922 to 1941.
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
, or seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
, in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
off the coast of central California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Location
Pioneer Seamount is located at 37° 21.1' North LatitudeLatitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, 123° 26.1' West Longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
, at the base of the continental slope of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
about 95 kilometers (51 nautical miles) off the coast just north of San Francisco
San Francisco, California
San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...
, California.
Physical characteristics
The seamount is a volcanoVolcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
between 10.9 and 11.1 million years old. It is about 12.8 kilometers (6.9 nautical miles) long as well as about 12.8 kilometers (6.9 nautical miles) wide, and has a volume of about 135 cubic kilometers (32.4 cubic miles). It rises about 1,930 meters (6,332 feet) above the surrounding ocean floor, and its peak is a minimum of 820 meters (2,696 feet) below the oceans surface. Samples from the seamount consist of highly vesicular alkalic basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
, hawaiite
Hawaiite
Hawaiite is an olivine basalt with intermediate composition between alkali olivine and mugearite. It was first described at the island of Hawaii. In gemology, hawaiite is a colloquial term for Hawaii-originated peridot,which is gem-quality olivine mineral....
, and mugearite
Mugearite
Mugearite is a type of orthoclase-bearing basalt, comprising olivine, apatite, and opaque oxides. The main feldspar in mugearite is oligoclase....
.
Biological environment
A wide variety of sealife lives on the seamount. CoralCoral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s dominate in deeper areas and sponges in its shallower parts.
Naming
Pioneer Seamount was named for PioneerUSC&GS Pioneer (1922)
USC&GS Pioneer was a survey ship that served in the United States Coast and Geodetic Survey from 1922 to 1941. She was the first ship of the Coast and Geodetic Survey to bear the name.-Construction and United States Navy service:...
, the first of three survey ships of the United States Coast and Geodetic Survey to bear the name. Pioneer operated along the United States West Coast and in the then-Territory of Alaska during her Coast and Geodetic Survey career, which lasted from 1922 to 1941.