. The Earth beneath the sea : History . Fig. 20. Distribution of sediments over the continental shelf and slope off More and Romsdal, West Norway. (From Holtedahl and Berthois, in Berthois, 1957.) Legend—1: mixed clay and sand; 2: fine sand; 3: sand; 4: coarse sand and gravel; 5: pebbles; 6: angular cobbles; 7: corals; 8: broken shells; 9: numerous stones; 10: rocky bottom. Depth contour to 200 m. Depressions on shelf not shown. However, geologists must be very cautious in generalizations, for sediments can settle in unexpected areas. Between the islands of the Molene archipelago, off West Bri
. The Earth beneath the sea : History . Fig. 20. Distribution of sediments over the continental shelf and slope off More and Romsdal, West Norway. (From Holtedahl and Berthois, in Berthois, 1957.) Legend—1: mixed clay and sand; 2: fine sand; 3: sand; 4: coarse sand and gravel; 5: pebbles; 6: angular cobbles; 7: corals; 8: broken shells; 9: numerous stones; 10: rocky bottom. Depth contour to 200 m. Depressions on shelf not shown. However, geologists must be very cautious in generalizations, for sediments can settle in unexpected areas. Between the islands of the Molene archipelago, off West Brittany, hydraulic "dunes" of different shapes, consisting of gravel and coarse sand, exist in many places below low water at spring tides, in spite of the fact that the maximum velocity of the tidal currents exceeds 5 knots. This results from numerous skerries which divide the current and create small shelters where deposition is possible. It can derive from the difference in velo- city between the ebb and the flood; this causes deposition at one side of the rocks, whereas at the opposite side the bottom remains rocky (Guilcher, in Bourcart, 1959). In such areas of very rugged submarine topography, the local environment plays an essential part in sedimentation: the characteristics of the
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