Near Coram the Ronkonkoma moraine turns sharply south, thence runs east just north 

 of Yaphank and then north again tln-ough Manorville and Calverton. In this southward sag, 

 the moraine is less massive than elsewhere, or else it has been partly buried by glacial outwash. 



Coram sink above mentioned lies at the westerly foot of a north and south ridge several 

 miles long, the southern end of which rests on the Ronkonkoma moraine. The hamlet of Middle 

 Island is on the east side of this ridge. Further east there is another ridge some five miles long 

 running more nearly northeast. These ridges form a "V" pointing south, the apex of which is 

 notched and occupied by Carmans river. In the "V" shaped area between the ridges there is a 

 small lake and a number of converging streams which drain the area to the north and parts 

 of the territory northwest of the westei'n ridge. These streams join to form Carmans river 

 which flows to the Atlantic. 



There is some evidence that the stream disappearing in Coram sink once flowed around 

 the northerly ends of these ridges to Peconic river. 



East of the easterly ridge and occupying the space down to and north of the sag in the 

 moraine is Camp Upton. This area is a sort of basin and is the headwaters of Peconic river. 

 There are numerous streams in it, but they all seem somewhat uncertain. Some run into sinks, 

 others have interrupted courses. Some show signs of having reversed the direction of flow. 

 Kettle holes and valleys are numerous and appear to define an earlier drainage system running 

 northerly towards Wading river. This section probably is a good gathering ground, but the 

 direction of underground flow is obscure and needs study. This particularly is true on account 

 of the wastes from the Laboratory. South of Ronkonkoma moraine and to the east a neck 

 extends to the south. Topographically this neck seems to differ somewhat from its neighbors. 

 It extends further south almost touching Great South Beach and it is but little eroded, Carmans 

 river runs along its west side. 



West of the neck and extending from the moraine at Yaphank to the bay there is a flat 

 bottomed valley about three miles wide, sloping to the south. 



This whole area needs study as to its history and the significance of the formations and 

 their effect on the ground water of the island. 



187 



