Nehalem Bank (Clatsop County, Oregon) Explained

Nehalem Bank
Other Name:The Shale Pile
Location:Pacific Ocean, near Tillamook Head
Coordinates:45.9°N -124.55°W
Type:Bar
Oceans:Pacific
Basin Countries:United States
Area:74.6km2
Max-Depth:160m (530feet)
Islands:No islands
Pushpin Map:Oregon
Pushpin Map Alt:Nehaalem Bank is located off the Oregon coast in the Pacific Ocean
Pushpin Map Caption:Nehalem Bank

Nehalem Bank is a bar, off the coast of Oregon, United States. It also has both rocky reefs and mud habitat, and is just northwest of Garibaldi Reef.[1] [2] [3]

Nehalem Bank runs between 150m (490feet) and 200m (700feet) deep, having an area of 74.6km2.[4] It is located off Tillamook Head, hence is off Clatsop County, and is barely south of the mouth of the Columbia River and Astoria Canyon.[5] Nehalem Bank is north of Nehalem Bay.

Nehalem Bank is one of the three major offshore banks of Oregon, the other two being Heceta Bank and Coquille Bank.[6] Nehalem Bank compares in size to Heceta Bank.[7]

Fishing

Nehalem Bank has been trawled, for shrimp.[8]

As of 2020, it is illegal to fish the Nehalem Bank with bottom trawl gear.[9]

Oceanography and Geology

Nehalem Bank has underwater sea stacks and paleoshorelines. There are rocky remnants of former seacliffs which are bored with intertidal pholad clam holes, testifying to what the level of the sea once was.[5]

Methane seeps are found, on Nehalem Bank, also, on Heceta Bank and Coquille Bank. These sites have microbial communities, also known as bacterial mats, in patches close to the sources of methane bubbles. They use methane for their metabolism. Whether the methane could be used the generate power is problematic, introduces many questions.[10]

A north-and northwest-striking geologic fault, the Nehalem Bank Fault, crosses the Nehalem Bank, is estimated to slip 0.5 to 5 millimeters per year.[11] [12] In the forearc of the Cascadia Subduction Zone, this fault underlies the continental shelf.[13]

See also

General references

Geologic references

Notes and References

  1. Web site: Gockel . Catherine . December 9, 2016 . Oregon Department of Fish and Wildlife . 2020-12-27.
  2. Web site: Gockel . Catherine . Offshore Seafood Processors in Federal Waters Off the Coast of Washington and Oregon (WAG520000) . 2020-12-27 . EPA.
  3. Web site: Hannah . Robert . Information Reports Number 2014-03 .
  4. Web site: Hannah . Robert . Effects of trawling for ocean shrimp (Pandalus jordani) on macroinvertebrate abundance and diversity at four sites near Nehalem Bank, Oregon .
  5. Web site: Embley . Bob . Mapping Ancient Shorelines . 2020-12-26.
  6. Web site: Milstein . Michael . March 8, 2008 . Oregon tsunami may turn out bigger than thought . December 28, 2020.
  7. Web site: McNeill . Lisa C. . August 2000 . Tectonics of the Neogene Cascadia forearc basin: Investigations of a deformed late Miocene unconformity . 2020-12-28.
  8. Web site: Hannah . Robert . Fish Division Oregon Department of Fish and Wildlife .
  9. Web site: Legal Information Institute . 2020-12-26.
  10. Web site: Floyd . Mark . June 6, 2018 . Oregon's Methane Coast . 2020-12-26.
  11. Web site: Nehalem Bank fault (Class A) No. 789 .
  12. Web site: Personius . Stephen F. . Map and data for Quaternary faults and folds in Oregon .
  13. Web site: Personius . S.F. . May 17, 2002 . Quaternary Fault and Fold Database of the United States . 2020-12-28.