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SUBMARINE CANYONS : DISTRIBUTION and LONGITUDINAL PROFILES By SUBMARINE CANYONS : DISTRIBUTION AND LONGITUDINAL PROFILES by Francis P. SHEPARD and Charles N. BEARD. (Reproduced from Geographical Review, New-York, July 1938, page 439). In the recent discussions of submarine canyons (1) there has been a tendency to base con­ clusions on the characteristics of selected examples, such as the canyons off Georges Bank, without much regard for the facts that the canyons are universal features and that they are associated with all kinds of conditions. Information on the distribution of many of the canyons has not been generally available, and there is practically no information regarding their longitu­ dinal profiles. In discussing these matters it seems advisable to take the opportunity of naming the canyons in order to facilitate future reference to them. BASIS FOR CANYON NAMES. In choosing names for the canyons (Table I) the Writers utilized practically all names used on charts and by earlier Writers such as Davidson (2) and H ull (3). In general, if a canyon heads towards a river mouth, the name of the river has been given to it. For other canyons the name of some shore feature or of a town in the vicinity Was used. However, there are a number of canyons whose heads are so far from the shore that it seemed unwise to name them after shore features. For these canyons names of vessels Were used, vessels being chosen that had played some part in the exploration of the canyons. In the lists in Table I the names of these canyons are underlined. One canyon off Georges Bank was named Georges Canyon because of its nearness to the dangerous Georges Shoal. CANYON DISTRIBUTION. The canyons located on Figure 1 include all about Which any information could be obtained. Of these, 102 examples Were chosen on the basis of the availability of enough soundings to per­ mit the construction of the longitudinal profiles. These profiles will constitute the main subject of discussion in this paper. However, dots Were placed on the map to show where other canyons have been discovered. For some of these canyons only a very small number of sound­ ings are available, so that one cannot be certain that the canyon has the V-shaped, steep- Walled profile of the typical submarine canyon. There are other types of submarine valley also, the two most notable being the submarine glacial trough and the submarine fault trough. These two types were omitted from the map, since it is evident from their characteristics that they are quite distinct in origin from the canyons (4). The canyons are found off every long stretch of coast except the Arctic and Antarctic, and the fact that none are known to be there may be due to lack of soundings. On the other hand, the distribution of the canyons is not uniform: they are found in large numbers off some coasts and are rare or entirely lacking off others. There are numerous canyons off the east coast of the United States north of Chesapeake Bay and off the West coast from the Mexican border to Humboldt Bay in northern California; and there are many from the Columbia River to the northern boundary of the United States. Canyons are common off the coasts of Korea, Japan, Formosa, and Luzon; off those of Ceylon and a part of eastern equatorial Africa; and off practically all the borders of the Mediterranean Sea. In most of the regions where canyons are either lacking or rare few soundings of the kind necessary for their discovery have been made. If the map (Fig. 1) had been made a few years ago, only one canyon, or perhaps three, could have been located off the entire east coast of the United States. This coast is bordered by a wide continental shelf, and detailed soundings had been made only on the shelf shoreward of the canyons. The same condition still exists for most of the broad continental shelves of other coasts of the world, so that future surveying will undoubtedly lead to the discovery of many more canyons. On the other hand, certain adequately sounded areas off the coasts of the United States lack canyons. These areas have an extremely gentle continental slope. If the river origin of the canyons is correct, the explanation of the absence of canyons in these areas is simple. 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