PLEISTOCENE GEOLOGY OF NASSAU CO. AND BOROUGH OF QUEENS 619 



and the northern ridge rude plains of coarse gravels rise gently 

 toward the southern face of the latter. Between the mounds them- 

 selves, these plains merge southward into a broad, slightly creased 

 plain, which sinks to the level of the marshes and the sea on the 

 south coast. 



The main ridge rises very frequently to a hight of 300 feet above 

 sealevel, and from 100 to 150 feet above the low ground at its base. 

 AYhere most distinct in its topographic features, its base is but little 

 more than a mile wide. Between Syosset on the south and East 

 Norwich and Brookville on the north side, this ridge is relatively 

 low and narrow. Betwe> n Jericho and Wheatley three or four 

 well marked spurs extend for one or two miles to the southward, 

 impinging on the line of aounds representing the continuation of 

 the southern ridge above (iscribed. West of this broad develop- 

 ment, the ridge becomes more massive and elevated, attaining its 

 liighest point in Harbor hi] 391 feet. West of Boslyn, it gradually 

 falls off in elevation, and fi )m Lake Surprise westward becomes a 

 low, flat ridge with a steep south rly front and with a gentle slope 

 • northward. The broad crest, seld m over 200 feet above the sea, is 

 cast into mounds and hollows, or knobs and basins, some of the latter 

 containing small tarns or lily ponds, a feature less common in the 

 eastern extension of the ridge. 



From the northern base of the ridge there extends a series of 

 plains or terraces, frequently at an elevation of about 200 feet near 

 the ridge, separated by the wedge-shaped harbors of the north shore. 

 These surfaces form the headlands or " necks," between the bays, 

 with elevations of from 100 feet to nearly 200 feet. The surface is 

 deeply indented by valleys mouthing on the broader indentations of 

 the coast line ; and in the vicinity of Oyster Bay harbor the land is 

 reduced to a few islands, now tied to the main island by marine 

 beaches. 



Between these rude plains on the north and the broad plain on 

 the south the deeper reentrants of the northern coast are continued 

 by narrow depressions across the main ridge. One of these troughs 

 occurs south of Manhasset, another at Hoslyn, and similar passes 

 traverse the ridge at the eastern base of the Harbor hill mass, on 

 the roa.d from Brookville to Locust Grove, and eastward along the 



