r»4<*» NVW YOKK STATE MTSEUM 



quudrHiigle comes to the surface south of that limit and flows in 

 Biimll streams to tlio sea 6u«^gests that clays are there immediately 

 beneath the surface veneer of sand and tine gravel. 



Tlie surface slopes seaward at the rate of about 15 feet to the 

 mile. Aside from the drainage creases above referred to, no other 

 lines of water action have been found within the area. The line of 

 contact with the moraines gradually rises from west to east, very 

 much as the elevation of the older Pleistocene increases on the north 

 of the moraine. Everywhere the plain appears to rise continuously 

 to tlie base of the moraines. The only possible exception to this 

 statement is found in the barlike ridge which lies northeast of Ilicks- 

 ville ; but the northern slope of this bar, much steeper on the whole 

 than it^ southeastern face, is not conclusively to be compared with 

 the northern margin of a frontal terrace plain such as that of 

 Nantucket, in which the outwash of sand and gravel has carried the 

 deposit up against the base of the ice front. If this deposit were of 

 such an origin, its northern slope would fix the front of the ice at 

 the time of the making of the outer line of morainal deposits, about 

 half a mile in front of the submarginal moraine, and this gravel bar 

 would somewhat antedate the part of the creased plain lying to the 

 west. 



The })lain everywhere on the south sinks beneath the surface of 

 the marsh without trace of a shore line action. So far as its present 

 surface is concerned, it appears to have arisen by the outwash of 

 streams in the manner of those extensive sheets of gravel, sand, and 

 glacier mud which confront the Malaspina and other existing gla- 

 ciers in high latitudes at the present day. 



With the completion of the iimer moraine and the sheeting over 

 of tlie southern outer slope with gravels and sands creased by out- 

 running streams, the principal work of the ice sheet on this portion 

 of the island ceased, and we next find indications of its front farther 

 nortii along the blnffHke descent to the present T^ong Island sound. 

 This front is lH?st marked at Port AVashington and on the area to the 

 wfhtward shown on the Harlem and Brooklyn quadrangles. 



Port Washington stage. The first definite trace of a halt 

 in the ice front after the retreat from the main moraine is found on 

 the northern and western extremity of Manhasset neck near Port 



