Landslide‐modifications of submarine valleys

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Abstract
Introduction—The continental shelves are accordant in level to such a degree that they must have been remarkably free from earth‐movements both during and since their formation. Yet these same stable shelves are traversed in many places by deep elongate depressions many of which are so similar to river valleys that they have been attributed to the submergence of the continental borders. Since most of the valleys have bases thousands of feet below sea‐level how could the sinking have occurred without throwing the shelves out of adjustment? A deep submergence at present would not only deform the shelf but would also cause deep indentations into the lands along the sides of the submerged valleys, but the coasts inside most of the submarine valleys are essentially straight. Obviously if these valleys were cut by rivers and then submerged this must have happened prior to the formation of the continental shelves and enough time must have elapsed to eliminate the estuaries which the submergence produced. Here again we meet obstacles. If the valleys have been submerged for a long time, why have they not been filled by sedimentation attendant upon the formation of the continental shelves? Also the valleys show various signs of recency such as their steep sides and their situation directly off rivers which are actively depositing sediment.

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