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Science Frontiers ONLINE No. 17: Fall 1981 |
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Submarine canyons: a 50-year perspective
F.P. Shepard has devoted most of his professional life to the study of submarine canyons. These great canyons, some cut through thousands of feet of hard crystalline rock, dwarf the largest land-based canyons. No wonder Shepard was fascinated enough to spend his life collecting data and weighing possible explanations. After 50 years, he has concluded that these colossal submarine features have no single cause. Subaerial erosion, turbidity currents, submarine slumping, and faulting have all played roles.
Anomalists will be most interested in Shepard's insistence that the evidence shows that subaerial erosion has played a major part in carving out the submarine canyons. This explanation is definitely frowned upon by most geologists because the Pleistocene sea levels dropped only about 100 meters according to current thinking. How could subaerial erosion account for canyons several thousand feet below present sea level? Shepard persists; the evidence is there. The continental margins must have risen and then sank back! He also points out that the Mediterranean seems to have dried up in recent geological times. Could the major oceans have dropped thousands of feet in a similar fashion? Shepard doesn't intimate this, saying only that the submarine canyons still present puzzles.
(Shepard, Francis P.; "Submarine Canyons: Multiple Causes and Long-Time Persistence," American Association of Petroleum Geologists, Bulletin, 65:1062, 1981.)
Reference. We catalog submarine-canyon anomalies under ETV1 in Carolina Bays, Mima Mounds. For more information on this book, visit: here.