SOILS OF THE SASSAFRAS SERIES. 7 



On the western end of Long Island, N. Y., the narrow belt of 

 Coastal Plain rises rather steeply from the coast line to the front 

 of the ridge which forms the northern border of the island. The 

 plain terminates against the front of this ridge at elevations of 

 100 to 240 feet above tide level. Within this sloping plain there 

 are also outlying hills and ridges, consisting of old glacial moraine, 

 which rise to considerable elevations above the surrounding sur- 

 face. These roughly divide the plains into a higher interior plain 

 and a lower coastal slope. These coalesce through intervals in the 

 ridge. Otherwise the plain is interrupted only by shallow stream 

 channels which are normally dry during a greater portion of the 

 year. 



The materials which constitute the older deposits of the North 

 Atlantic Coastal Plain are chiefly unconsolidated gravel, sands, 

 loams, clays, and marls, although there are local occurrences of in- 

 durated clays and iron-cemented sands and gravels of little thickness 

 and of limited extent. 



These sediments of varying degrees of coarseness have been de- 

 rived from the adjacent, interior land areas, transported to the older 

 shore lines, and deposited at various periods of geologic time as 

 successive layers or strata in the older marine or estuarine waters. 

 The surfaces of all of these older deposits are marked by a seaward 

 slope and the oldest formations reach the surface along the inner 

 margin of the Coastal Plain while the younger ones are successively 

 encountered at or near the surface in a seaward direction. These 

 older formations, from the Cretaceous to the Miocene in geologic 

 age, form the basal structure of the Coastal Plain. They reach the 

 surface chiefly along the lines of greatest erosion near the inner 

 margin of the region and they are very extensively covered by later 

 deposits, forming the terraces and the greater part of the seaward 

 slopes of the present land surfaces. These later deposits are referred 

 by geologists to the Pliocene and Pleistocene periods. They im- 

 mediately preceded the present geologic time. 



The soils of the Sassafras series are chiefly derived from the de- 

 posits of the Pleistocene age. This is the latest completed geologic 

 period before the present time. It was marked in the northern por- 

 tion of the area under discussion by two or more invasions of glacial 

 ice. During the period of ice occupation, and particularly while the 

 ice sheet Avas melting and its front receding, large amounts of ma- 

 terial were deposited near its front in the form of glacial outwash. 

 At the same time other glacial material was carried down all of the 

 larger streams of the region to be deposited as a part of the material 

 of the Pleistocene terraces, which were being formed at the same time 

 along the coast. 



