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Monterey Canyon, or Monterey Submarine Canyon, is a
submarine canyon A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km, from c ...
in
Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by ...
,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
with steep canyon walls measuring a full 1 mile in height from bottom to top, which height/depth rivals the depth of the
Grand Canyon The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , Southern Paiute language: Paxa’uipi, ) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a m ...
itself. It is the largest such submarine canyon along the West coast of the North American continent, and was formed by the underwater erosion process known as turbidity current erosion. Many questions remain unresolved regarding the exact nature of its origins, and as such it is the subject of several ongoing geological and marine life studies being carried out by scientists stationed at the nearby
Monterey Bay Aquarium Research Institute The Monterey Bay Aquarium Research Institute (MBARI) is a private, non-profit oceanographic research center in Moss Landing, California. MBARI was founded in 1987 by David Packard, and is primarily funded by the David and Lucile Packard Founda ...
, the Moss Landing Marine Laboratories, and other
oceanographic Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...
institutions. Monterey Canyon begins at Moss Landing, California, which is situated along the middle of the coast of
Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by ...
, and extends horizontally under the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five 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 the conti ...
where it terminates at the Monterey Canyon
submarine fan Abyssal fans, also known as deep-sea fans, underwater deltas, and submarine fans, are underwater geological structures associated with large-scale sediment deposition and formed by turbidity currents. They can be thought of as an underwater ver ...
, reaching depths of up to 3,600 m (11,800 ft) below surface level at its downstream mouth. It is a part of the greater Monterey Bay Canyon System, which consists of Monterey, Soquel and Carmel Canyons. The canyon's depth and nutrient availability (due to the regular influx of nutrient-rich sediment) provide a habitat suitable for many marine life forms. The
Soquel Canyon State Marine Conservation Area Soquel Canyon State Marine Conservation Area (SMCA) is an offshore marine protected area in Monterey Bay. Monterey Bay is on California’s central coast with the city of Monterey at its south end and the city of Santa Cruz at its north end. T ...
protects a side-branch of the Monterey Submarine Canyon. Like an underwater park, this marine protected area helps conserve ocean wildlife and marine ecosystems.


Geomorphology

While the erosion process of turbidity current erosion which once carved out the submarine Monterey Canyon is well known, the cause of the great depth and length of this canyon, obviously carved out millions of years ago, and the unusually large size of the sedimentary deposit (fan) at its underwater mouth 95 miles West of Monterey, have all been a cause for some speculation. Typically submarine canyons of this depth and length which cut so far across a continental shelf, and with such large sedimentary fans attached, are only formed when aligned to receive the outflows of very major rivers, such as the Mississippi or the Amazon, and such canyons are not typically found in alignment with relatively low flow rivers such as the Salinas River. One dominant theory holds that the canyon is a remnant of an ancient outlet of the
Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...
which once existed before the
Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...
opened up about 7.9 million years ago. Others believe that it may represent the remnant outlet of a larger river that may have once drained the Central Valley, possibly even via the Los Angeles Area Catchment Basin. The Salinas River is thought to have been the outlet for prehistoric Lake Corcoran, which once occupied much of the Central Valley. The Upper Turbidite Unit of the Monterey submarine fan may have formed soon after Lake Corcoran found a new outlet and was catastrophically drained via what is now San Francisco Bay, when sediment from the former lake bed was carried out its new outlet and then down to Monterey Bay by
longshore drift Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle) along a coast parallel to the shoreline, which is dependent on the angle incoming wave direction ...
. Reconstructions of ancient land configurations via
plate tectonic Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
theory indicate that the canyon has moved north to its current location via the horizontal slip-action of the
San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal) ...
and would have been approximately where Santa Barbara is located when both the San Andreas Fault and the Gulf of California came into being. Similar undersea canyons exist at the mouths of other large rivers around the world today, for instance, the
Hudson River Canyon The Hudson Canyon is a submarine canyon that begins from the shallow outlet of the estuary at the mouth of the Hudson River. It extends out over seaward across the continental shelf finally connecting to the deep ocean basin at a depth of 3 to ...
. As no major river lies at the head of Monterey Canyon today, it is surmised that it may have come into being when such a river did so in the past. The clues to the ancient origins of this canyon lie somewhere at the 2 mile deep downstream mouth of the canyon in a huge sedimentary bed called the Monterey Fan. This fan appears to be far too massive to have accumulated from the modern coastal streams. Research including core sampling is ongoing. Thus far, only "recent" sedimentary cores have been obtained. The oldest cores lie deeply buried, and remain to be probed. Once these deeper core samples have been properly analyzed and traced back to their original sedimentary sources, the answers to such speculations as to which river might have provided the high level of turbidity current flows which are believed to have most probably been required to carve out such a deep and long canyon, with such a huge sedimentary deposit (fan) at its mouth will all hopefully be finally resolved.


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External links


Moss Landing Marine Laboratories website
{{Monterey Bay Area Canyons and gorges of California Monterey Bay Submarine canyons of the Pacific Ocean Landforms of Monterey County, California Landforms of Santa Cruz County, California Physical oceanography