at about 15 fathoms, drops to 20 fathoms north of Sunken Meadow, briefly drops to below 25 

 fathoms north of Old Field point and thence continues easterly under the 20 fathom line. East 

 of Old Field point the 15 fathom depth expands easterly into a triangular shape bounded on 

 the east by the meridian of Fresh Pond landing, northeast of Calverton, up to a point about 

 six miles south of Sachem head and Faulkners island in Connecticut, thence easterly as a 

 channel as far as the meridian of the mouth of the Hammonasset. 



Starting at Hart's island-Hewlett point line (Queens-Nassau line) on the west the sound 

 deepens to over five fathoms near both shores but does not reach 10 fathoms before the western 

 end of the trough is met. It is constricted by a shoal running out from Eaton neck to meet 

 another running south from Wilson Point (Norwalk) and again on the line at Stratford point 

 (Housatonic river), Old Field point (west of Port Jefl'erson harbor), by a shoal running south 

 from the first point and a good sized bar or near island in the center of the sound. The deepest 

 point in the sound is off Norwalk; one almost as deep is in the above trough off Old Field 

 point. The sill which would limit the drawdown of the sound were sea level to be depressed is 

 a line running from Cornfield (Connecticut river) to Roanoke point (north of Riverhead) 

 and is less than 15 fathoms deep. East of this line the outlet of the sound to the east is blocked 

 by the extensive delta deposits of the Connecticut, of irregular contour, grooved and pitted by 

 tidal scour. The submerged channel of the Connecticut runs easterly to The Race (off the west 

 end of Fishers island) and thence continues through the intermorainal space (Block Island 

 sound) through the southern morain between Montauk point and Block island. There is a well 

 marked broad depression in the ocean floor running a little east of south to the Hudson sub- 

 marine canyon over 120 miles distant. The sill of the channel at Block island is less than 15 

 fathoms. The Race is depressed to over 25 fathoms, and the submerged channel running east 

 to the north of Block island is about 20 fathoms. 



Basically, Long Island is the unsubmerged portion of a gently sloping, slightly concave 

 plain, the upper edge of which has been plowed out to form Long Island sound. The north 

 shore is a more or less abrupt escarpment from the top of which the surface slopes to the 

 south and east passing under the waters of the Atlantic. The whole island is slightly down to 

 the eastward and probably continues submerged far to the east, the New England islands 

 being part of the same general formation. 



The north shore is indented by many bays and harbors with intervening necks and off -lying- 

 islands connected by bar beaches. The south shore in general changes to swamps and lagoons 

 at sea level, which last are contained by long barrier beaches topped by dunes. There is a 

 westerly drift of sand all along these beaches. 



The north shore, except in the bays, is being eroded by wave wash. The bays are filling. 

 The south shore lagoons are filling. The beaches are moving westward. From Napeague beach 

 to Montauk point the south shore is eroding. 



The most conspicuous features of the topography are the two moraines of the latest Wis- 

 consin ice advance which traverse the island from end to end with an intermorainal trough 

 between them except where they merge and cross near Lake Success. The older of these, 

 Ronkonkoma moraine, starts at Montauk point and runs well inland on the island to Lake 

 Success, thence westerly from Little Neck bay to East river. In this last area there seem to be 

 several deposits of morainal material; that just north of Newtown creek may be the main 

 branch. To the eastward of Montauk point this moraine also forms Block island and others 

 beyond. 



The younger. Harbor Hill moraine, starts in Brooklyn at the Narrows opposite Staten 

 island and runs thence to Lake Success and continues along the heads of the bays to Port 

 Jefferson. East of that point it crowns the north shore escarpment, and has been heavily eroded. 



160 



