Talk:Submarine canyon

No citations

This article needs some supporting citations - interesting discussion about the evolution of thinking on formation processes, but there's no way to tell if the information is credible or not. 67.241.183.247 (talk) 16:31, 22 February 2009 (UTC)

Water level?

I do not understand why the sea level must have been 3000m lower in former times in order to form submarine canyons. The deepest is 1km. Did the author mean 3000ft?

One other thing: "Canyons may have been carved by turbidity currents, or dense, sediment-laden currents triggered by earthquake which flow down the continental margin." sound definitely wrong. I changed this to "Canyons may have been carved by turbidity currents (dense, sediment-laden currents which flow down the continental margin, triggered e.g. by earthquakes)", because a turbidite current is just what the next words discribe. The meaning of "Submarine canyon" is an underwater canyon.

Kind regards, Heiko Evermann 22:12, 22 October 2005 (UTC)

"The difficulties encountered in explaining the lowering of sea level necessary for the canyons to have been cut by streams [with a volume of water such as we have today] seem insurmountable.. If Tolstoy's conclusion that Hudson Canyon extends down to a depth of 15,000 feet [4572 ml [!] is correct, the magnitude of lowering of sea level to permit subaerial canyon cutting seems beyond any possibility of realization." *William D. Thombury, Principles of Geomorphology, (1954), p. 472.

"Can we, as seekers after truth, shut our eyes any longer to the obvious fact that large areas of sea floor have sunk vertical distances measured in miles?" *Kenneth K. Landes, "Illogical Geology, " in Geotimes, March 1959, p. 19.

"How did they get there? What forces could gouge out canyons that are sometimes 15,000 feet below sea level? Was the ocean floor raised or the ocean surface lowered by this amount so ancient rives could cut these canyons? If so, how? Canyons on the continents were supposedly formed by the cutting of fast flowing rivers and surface drainage. However, the flows measured in submarine canyons are much too slow--generally less than one mile per hour. Frequently the flow is in the wrong direction. Submarine landslides or currents of dense, muddy water sometimes occur. However, they would not form the long, branching (or dendritic) patterns that are common to river systems and submarine canyons. Besides, experiments with mud-ladened water in actual submarine canyons have not demonstrated any canyon-cutting ability." *Walter T. Brown, In the Beginning (1989), p. 63.

Does anyone know where the above claims of 15,000 ft below sea level come from? If so, does this prove that sea levels were at one time 4 miles below their current levels?

Joe

We don't need to postulate such extreme changes in sea level. The likely explanation for the initiation of most canyons, is that they start by slumping on the slopes themselves forming a 'gouge'. The gouged area then migrates up the slope by progressive slumping of the material above it, the headwall to the slump. Eventually, it reaches the shelf and continues to cut back into that by continued 'headward erosion' as the steep canyon sides progressively collapse. This explains why they are not always associated with rivers. They are further eroded by fast-moving turbidity currents. I'll try to add all this into the article, when I get the time, but the reference that I just added has some good information. The image that I just added shows five canyons, of which only the Hudson is connected to a river. Mikenorton (talk) 21:34, 26 January 2012 (UTC)

Date of Discovery

In a link to this section, "Continental Shelf" mentions that submarine canyons were only recently found out about.

Any mention of a date on this page would seem appropriate.

~boromadloon~