Bowie Seamount
Bowie Seamount | |
---|---|
Kodiak-Bowie Seamount chain | |
Age of rock | Pleistocene |
Last eruption | 18,000 years ago[2] |
Bowie Seamount, or SG̱aan Ḵinghlas ("Supernatural One Looking Outward") in the Haida language,[3][4] 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 also known as Bowie Bank. The English name for the feature is after William Bowie of the United States Coast and Geodetic Survey.[5]
The volcano has a flat-topped summit rising about 3,000 m (10,000 ft) above the
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. It is adjacent to two other submarine volcanoes; Hodgkins Seamount on its northern flank and Graham Seamount on its eastern flank.
Geology
Structure
With a height of at least 3,000 m (10,000 ft) and rising to within only 24 m (79 ft) of the sea surface, Bowie Seamount is the shallowest submarine volcano on the British Columbia Coast, as well as in Canadian waters, and one of the shallowest submarine volcanoes in the northeast Pacific Ocean.[1][2] Most seamounts are found hundreds to thousands of metres below sea level, and are therefore considered to be within the deep sea. If Bowie Seamount were on land it would be about 600 m (2,000 ft) higher than Whistler Mountain in southwestern British Columbia and 800 m (2,600 ft) lower than Mount Robson, the highest mountain in the Canadian portion of the Rocky Mountains.[2]
Bowie Seamount is about 55 km (34 mi) long and 24 km (15 mi) wide.
Eruptive history
Bowie Seamount was formed by
Close to Bowie's submerged summit, former coastlines cut by wave actions and beach deposits show that the submarine volcano would once have stood above sea level, as either a single volcanic island or as a small cluster of shoals that would have been volcanically active. Sea levels during the last glacial period, when Bowie Seamount was formed, were at least 100 m (300 ft) lower than they are today.[1][2] It would have had a land area similar to, if not larger than, Midway Atoll in the central Pacific Ocean.
Origins
There is some disagreement about the origin of Bowie seamount: Geological studies indicate that the
The volcanic rocks which make up some of the seamounts in the Kodiak-Bowie Seamount chain are unusual in that they have an acid-neutralizing chemical substance like typical ocean-island basalts but a low percentage of strontium as found at mid-ocean ridge basalts. However, the strontium-bearing volcanic rocks comprising Bowie Seamount also contain lead. Therefore, the magma mixtures that formed Bowie Seamount seem to have originated from varying degrees of partial melting of a depleted source in the Earth's mantle and basalts which had distinctly high lead isotopic ratios. Estimates during geological studies indicate that the abundance of the depleted-source component ranges from 60 to 80 percent of the erupted material.[8]
Some aspects of the origin of the Kodiak-Bowie Seamount chain remain uncertain. The volcanic rocks found at the
Although some of the seamounts in the Kodiak-Bowie Seamount chain appear to follow the expected age progression for a mantle plume trail, others, such as Denson Seamount, are older than that hypothesis would suggest.[9] As a result, the Kodiak-Bowie Seamount chain has also been proposed by geoscientists to be a mix of ridge and mantle plume volcanism.
Biology
Bowie Seamount supports a biologically rich area with a vigorous ecosystem. Studies have recorded high densities of
SGaan Kinghlas-Bowie Seamount Marine Protected Area
Because of its biological richness, Bowie Seamount was designated as Canada's seventh
The Marine Protected Area measures about 118 km (73 mi) long and 80 km (50 mi) wide, totaling an area of 6,131 km2 (2,367 sq mi).[12] The Bowie Seamount Marine Protected Area also includes Peirce Seamount (also called Davidson Seamount) and Hodgkins Seamount.[11] Previous to this designation, beginning in 1997, Bowie Seamount was a Haida marine protected area.[13]
Diving explorations and studies
The shallow depth of Bowie Seamount makes it the only underwater mountain off the British Columbia Coast easily reached using
In August 1969, Canadian Forces Maritime Command divers made more dives during scientific studies by the Fisheries Research Board of Canada. They found very dense shoals of rockfish floating over Bowie's flat-topped summit and a variety of bottom life. A number of monochrome photographs were taken and a few seaweeds were collected, but no species record was created for other types of oceanic life around Bowie Seamount.[7]
In November 1996, an issue of the
Scientist Bill Austin of Khoyatan Marine Lab in the Northeast Pacific examined a video made during the National Geographic dives to identify the
A team of five divers, led by photographer/videographer Neil McDaniel, visited the seamount August 3–5, 2003 and conducted a biological and photographic survey of the summit down to depths of about 40 m (130 ft). A total of 18 taxa of algae, 83 taxa of conspicuous invertebrates and 12 taxa of fishes were documented, approximately 180 underwater still photographs were taken and approximately 90 minutes of digital video were recorded. Of particular note were the dense schools of rockfish hovering over the summit and numerous curious prowfish.[7]
Indigenous people
To the Haida, the indigenous people who played a key role in establishing the Bowie Seamount Marine Protected Area, the submarine volcano is called SGaan Kinghlas. In Haida language it means "Supernatural Being Looking Outward".[11]
Haida have long recognized seamount as a special place. Gidansda Guujaaw, former President of the Council of the Haida Nation, has said: "SGaan Kinghlas represents a shift in recognizing the need for respect and care for the Earth. This is a very significant turning point in reversing the trends that have been leading to the depletion of life in the sea."[11]
Marine hazard
Given its shallow depth, Bowie Bank is a potential marine hazard. Waves up to 27 m (89 ft) high have been recorded along the
See also
- Volcanism of Western Canada
- List of volcanoes in Canada
- List of Marine Protected Areas of Canada
- Bowie hotspot
References
- ^ a b c d e f g "Bowie Seamount Marine Protected Area Management Plan" (PDF). Fisheries and Oceans Canada. August 2001. Archived from the original (PDF) on 2009-03-24. Retrieved October 27, 2008.
- ^ a b c d e f g h i "The Bowie Seamount Area" (PDF). John F. Dower and Frances J. Fee. February 1999. Archived from the original (PDF) on 2009-03-24. Retrieved October 27, 2008.
- ^ "DFO SGaan Kinghlas-Bowie Seamount Marine Protected Area". www.dfo-mpo.gc.ca/. Department of Fisheries and Oceans Canada. Retrieved 2018-01-16.
- ^ "SGAAN KINGHLAS BOWIE SEAMOUNT MARINE PROTECTED AREA MONITORING INDICATORS, PROTOCOLS AND STRATEGIES" (PDF). www.dfo-mpo.gc.ca/. Department of Fisheries and Oceans Canada. Retrieved 2018-01-16.
- ^ "Undersea Features History". GEOnet Names Server. Archived from the original on 2012-02-11. Retrieved 2012-03-07.
- ^ "Submarine Volcanoes, Vents, Ridges, and Eruptions". USGS. March 13, 2005. Retrieved October 27, 2008.
- ^ a b c d e f "Biological Observations at Bowie Seamount: August 3-5, 2003" (PDF). N. McDaniel, D. Swanston, R. Haight, D. Reid and G. Grant. October 22, 2003. Archived from the original (PDF) on 2009-03-24. Retrieved November 6, 2008.
- ^ ISBN 978-3-540-67772-7.
- ^ a b "Seamounts in the Eastern Gulf of Alaska: A Volcanic Hotspot with a Twist?". National Oceanic and Atmospheric Administration. July 12, 2005. Retrieved October 27, 2008.
- ^ a b "Bowie Seamount Marine Protected Area". Fisheries and Oceans Canada. May 25, 2006. Archived from the original on 2009-03-01. Retrieved October 27, 2008.
- ^ a b c d e "Bowie Seamount Designated as Canada's Seventh Marine Protected Area". Fisheries and Oceans Canada. April 19, 2008. Archived from the original on September 11, 2009. Retrieved October 27, 2008.
- ^ a b "Designation of Bowie Seamount as a Marine Protected Area". Fisheries and Oceans Canada. October 11, 2008. Archived from the original on May 20, 2011. Retrieved October 30, 2008.
- ^ "SGaan Kinghlas–Bowie Seamount Gin siigee tl'a damaan kinggangs gin k'aalaagangs Marine Protected Area Management Plan 2019" (PDF). Council of the Haida Nation / Fisheries and Oceans Canada. 2019. Retrieved 2023-06-02.
- ISBN 1-57785-658-9.
- ISSN 0706-6457.
External links