Cascadia Channel

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Coordinates: 43°30′00″N 130°00′00″W / 43.50000°N 130.00000°W / 43.50000; -130.00000
Source: Wikipedia, the free encyclopedia.

Cascadia Channel is the most extensive

river tributaries.[2]

Cascadia Channel has two contributing tributaries—

Quinault and Willapa Channels in the south.[2] The channel is believed to be over 2,200 kilometres (1,400 mi) long.[1]

Formation

Headed north-south, Cascadia Channel initially formed on the eastern flank of the

Pleistocene glaciation and the lowering of sea level, much sand and gravel from the shore deposited on either the upper slope or the outer shelf, which initiated turbidity currents, converting the lower and middle portions of the channel into erosional features. This led to the initiation of downcutting. At this time, apparently the channel built up by turbidity current that proceeded south, along the western part of the Cascadia abyssal plain, also from the west of the Astoria Fan. During the Holocene, turbidity current from the Columbia River sediment continued to flow, both down the Cascade channel and the Blanco Fracture Zone.[3]

Marine Biology

In the channel, the

benthic animal population is four times as abundant compared to the surrounding Juan de Fuca Plate. In Cascadia Channel, burrowing organisms have left many well-preserved burrows of distinct sizes and shapes in turbidity current deposits.[4]

Turbidite Flows

An earthquake can trigger a

sediment flow
, which may begin as a slide or slump, continue as a debris flow, and change into a turbidity current as fluid content increases down slope.

deep-sea channels and abyssal fans
.

turbidity currents.[2]

In 1990, John Adams of the

turbidites in core samples from both side and main channels, indicating that each turbidity current was likely caused at the same time, by the same event which may be the 1700 Cascadia earthquake
.

Of the turbidites, large storms are not the likely source.[5]

Ash from the eruption of

submarine canyons.[2]

Local geography

References

  1. ^ a b Gary Bruce Griggs. "Cascadia Channel: The Anatomy of a Deep-Sea Channel" (PDF). Retrieved 4 September 2017.
  2. ^ a b c d Brian F. Atwater and Gary B. Griggs (2012). "Deep-Sea Turbidites as Guides to Holocene Earthquake History at the Cascadia Subduction Zone— Alternative Views for a Seismic-Hazard Workshop" (PDF). USGS. Retrieved 11 September 2017.
  3. doi:10.1029/JC078i027p06325
    .
  4. doi:10.1016/0011-7471(69)90071-0.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  5. ^ "Turbidite evidence". Pacific Northwest Seismic Reference. Retrieved 14 September 2017.

External links and references

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