Bowie Seamount

Bowie Seamount is a large submarine volcano in the northeastern Pacific Ocean, located 180 km (110 mi) west of Haida Gwaii, British Columbia, Canada.

The seamount is named after William Bowie of the Coast & Geodetic Survey.

The volcano has a flat-topped summit (thus making it a guyot) rising about 3,000 m (10,000 ft) above the seabed, to 24 m (79 ft) below sea level. The seamount lies at the southern end of a long underwater volcanic mountain range called the Pratt-Welker or Kodiak-Bowie Seamount chain, stretching from the Aleutian Trench in the north almost to the Queen Charlotte Islands in the south.

Bowie Seamount lies on the Pacific Plate, a large segment of the Earth's surface which moves in a northwestern direction under the Pacific Ocean. Its northern and eastern flanks are surrounded by neighboring submarine volcanoes; Hodgkins Seamount on its northern flank and Graham Seamount on its eastern flank.

Geology

Structure

Seamounts are volcanic mountains which rise from the seafloor. The unlimited supply of water surrounding these volcanoes can cause them to behave differently from volcanoes on land. The lava emitted in eruptions at Bowie Seamount is made of basalt, a common gray to black or dark brown volcanic rock low in silica content (the lava is mafic). When basaltic lava makes contact with the cold sea water, it may cool very rapidly to form pillow lava, through which the hot lava breaks to form another pillow. Pillow lava is typically fine-grained, due to rapid cooling, with a glassy crust, and has radial jointing.

Seamount

A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface (sea level), and thus is not an island. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 metres (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 metres (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts"

A total of 9,951 seamounts and 283 guyots, covering a total area of 8,796,150 km2 have been mapped but only a few have been studied in detail by scientists. Seamounts and guyots are most abundant in the North Pacific Ocean, and follow a distinctive evolutionary pattern of eruption, build-up, subsidence and erosion. In recent years, several active seamounts have been observed, for example Loihi in the Hawaiian Islands.

Gulf of Alaska

The Gulf of Alaska is an arm of the Pacific Ocean defined by the curve of the southern coast of Alaska, stretching from the Alaska Peninsula and Kodiak Island in the west to the Alexander Archipelago in the east, where Glacier Bay and the Inside Passage are found.

The entire shoreline of the Gulf is a rugged combination of forest, mountain, and a number of tidewater glaciers. Alaska's largest glaciers, the Malaspina Glacier and Bering Glacier spill out onto the coastal lain along the Gulf of Alaska. The coast is also heavily indented, with Cook Inlet and Prince William Sound the two largest connected bodies of water, but also including Yakutat Bay and Cross Sound. Lituya Bay is the site of the largest recorded tsunami in history and is a popular sheltered anchorage for fishing boats.

Ecology

The Gulf of Alaska is considered a Class I, highly productive ecosystem (more than 300 grams of carbon per square meter per year) based on SeaWiFS data.

Many deep water corals can be found in the Gulf of Alaska. Primnoa pacifica has contributed to the location being labeled as Habitat Areas of Particular Concern.P. pacifica is typically a deep water coral normally found between 150 metres (490 ft) and 900 metres (3,000 ft) here.

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south and is bounded by Asia and Australia in the west and the Americas in the east.

At 165.25 million square kilometers (63.8 million square miles) in area, this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of the Earth's water surface and about one-third of its total surface area, making it larger than all of the Earth's land area combined.

The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific. The Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 metres (35,797 ft).

The eastern Pacific Ocean was first sighted by Europeans in the early 16th century when Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and discovered the great "southern sea" which he named Mar del Sur. The ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favourable winds on reaching the ocean. He called it Mar Pacifico, which in both Portuguese and Spanish means "peaceful sea".

Kodiak–Bowie Seamount chain

The Kodiak–Bowie Seamount chain, also called the Pratt–Welker Seamount chain, is a seamount chain in southeastern Gulf of Alaska stretching from the Aleutian Trench in the north to Bowie Seamount, the youngest volcano in the chain, which lies 180 km (112 mi) west of the Queen Charlotte Islands, British Columbia, Canada. The oldest volcano in the chain is the Kodiak Seamount. Although the Kodiak Seamount is the oldest extant seamount in the Kodiak-Bowie chain, the adjacent lower slope contains transverse scars indicating earlier subduction of seamounts.

The Kodiak–Bowie Seamount chain are mostly extinct volcanoes that formed above the Bowie hotspot. This is a 100-to-150-km-wide morphological swell presumably of thickened hotspot generated crust, although there are no seismic refraction data across the swell to define crustal thickness. The crest of one such peak, Patton Seamount originally formed off Washington state as a submerged volcano 33 million years ago. Over time, as the Pacific Plate moved steadily northwest, Patton Seamount was carried off the Bowie hotspot and into the Gulf of Alaska. New volcanoes were formed one after another over the hotspot, creating the Kodiak–Bowie Seamount chain.