THE GEOLOGY OF LONG ISLAND, ETC. 



mitting these parts to be occupied by the estuaries of the 

 sea, and causing - a slackening of the drainage. Such is the 

 condition at Cold Spring Harbor. (Johnson and York, 

 Conard, lac. cit.) 



"Cold Spring Harbor," which extends back in the country 

 for 3 miles from the upper end of the harbor, is a sunken 

 river valley. In the valley runs the stream of Cold Spring 

 Creek, which expands at three different levels into broad, 

 deep and shallow ponds connected by waterfalls and shaded 

 by dense foliage. Cold Spring Creek, flowing laden with 

 silt into the upper end of the harbor has aided the sea in 

 forming the sandsp-it, which nearly cuts off an inner basin 

 having an area of 110 acres at high water and 45 acres at 

 low water, the mean range of the tide being 7.75 ft. and 

 the maximum depth being 7 ft. over an area 100 ft. in dia- 

 meter. The inner harbor is silting up, and its water is 

 decidedly brackish at high tide varying from 1.006 to 1.016 

 at the surface and from 1.006 to 1.018 at the bottom. 



The passage from the inner basin to the harbor is only 

 200-300 ft. wide at low tide, and through this gut the water 

 flows at times with great rapidity. The steep sides of the 

 harbor are piles of glacial drift full of clay, siliceous sand 

 and gravel and boulders of varying size. This determines 

 the prevailing character of the shore line, sandy or gravelly 

 beaches with boulders extending into deep water and most 

 abundant at the base of the worn off bluffs. Mud flats are 

 common, but for the most part are underlaid with sands at 

 a depth of 1-3 ft. A mud flat extends from parts of the 

 sandspit at the level of mean low tide. No rock occurs in 

 place, but on many headlands the accumulated boulders 

 form an extensive rock work. At intervals the shore line 

 is diversified by salt meadows, partly enclosed salt ponds 

 and shallow harbors and bays. 



Opening into Cold Spring Harbor at about the middle 

 of its western side is Oyster Bay, a tortuous body of water 

 running back some 6-7 miles and having a breadth varying 

 from li/o miles to I/2 niile. Oyster Bay also receives at its 



* Following the account of Davenport, C. B., and Johnson, D. S. 

 The Flora about Cold Spring Harbor ('98). 



—11— 



