SURFACE TOPOGRAPHY 



Long Island sound is a body of salt water lying in a depression eroded in the landward 

 margin of the continental shelf. It is bounded on the north by the concave, rocky coast of 

 Westchester county and the State of Connecticut, on the south by the somewhat abrupt north 

 shore of Long Island, curving in a direction opposite to the north shore and composed almost 

 entirely of unconsolidated materials. On the west it connects with East river through Hell- 

 gate. On the east it is limited by a picket line of islands, part of a glacial moraine, extending 

 from Orient point on Long Island to Watch hill in the southwest corner of Rhode Island. The 

 maximum width is about 23 miles, just east of New Haven. 



It is reasonable to believe that the combination of natural phenomena which caused the 

 sound to be excavated did not cease to operate at Watch hill and that the sound is but the 

 western end of a depression which extends far to the east. In that case the New England 

 islands would represent the high points on an easterly continuation of the south fluke of Long 

 Island which are high enough to rise above the ocean. It will be noted that Long Island 

 itself appears to be lower at the east end, a feature common to the entire continental shelf 

 (9) (GW-2 — Fig. 7), as above noted. In front of Rhode Island this shelf is entirely submerged 

 except for isolated islands. 



Long Island sound receives all northward flowing drainage of Long Island, which is rather 

 small in volume, also the drainage from a considerable portion of Westchester and adjacent 

 counties in New York and all the drainage from Connecticut. The only real river entering the 

 sound is the Connecticut itself which enters at the extreme eastern end. 



There are strong tidal currents in Hellgate, but it is thought that the bulk of the out-flow 

 of water from the sound is to the east. To escape to the ocean, this water has to pass over two 

 barriers, the moraines and underlying formations which extend for the entire length of Long 

 Island and continue further to the east. 



Study of the Coast Survey charts shows that under present conditions the out-flow passes 

 the inner barrier through Plum gut and The Race, just west of Fishers island. The second 

 barrier is passed between Montauk point and Block island, and thence the water flows in a 

 southerly direction over a well marked channel in the continental shelf in the general direction 

 of the Hudson canyon. Perhaps it would be better to say that the above would be the course 

 followed were sea level to be reduced by several hundred feet. With the present ocean level the 

 escaping water, although generally following the above course, is spread out and diifused 

 through salt water, affected by tidal phenomena and other things so it does not flow in a well 

 appointed stream. It is probable that a portion of the flow is eastward in a well developed 

 depression passing north of Block island. 



The configuration of the bed of Long Island sound is irregular and complicated. The north 

 shore is practically on rock. Only as it enters East river is exposed rock found on the south 

 but this serves to establish a sill to escape in that direction and under the existing channel. 

 Little is known of the rock surface under most of the sound but as far as known, rock contours 

 as given here are approximately parallel to the north shore. A well on Orient point struck rock 

 at Elevation -654. 



A deep, rather narrow trough generally follows the 41° :00' parallel of latitude and extends 

 from close to the Connecticut shore east of the mouth of Mianus creek to a point not far from 

 the north shore of the island at about the meridian of Baiting Hollow. This starts at the west 



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