Hollick: Features of Silver Lake Basin 6r 



Gratacap read a paper on the results of a series of soundings in 

 the lake, made in cooperation with Mr. Ernest Congdon.^ The 

 greatest depth of water recorded was i6 ft. lo in., and the 

 temperature of the surface water and that of the deepest part 

 were found to be, respectively, 76° and 70° Fahr. 



At a meeting of the Association held October 10, 1903, it was 

 my privilege to read a paper entitled Depth and Form of the 

 Silver Lake Basin,* based upon accurate surveys and soundings 

 made in connection with condemnation proceedings for the then 

 projected Silver Lake Park. The greatest depth recorded was 

 18 ft. 6 in., and the form of the basin was illustrated by a 

 series of contour lines joining the points indicating equal depth. 

 At the February meeting following, I presented a second paper, 

 on Some Recently Discovered Facts in Regard to Silver Lake,^ 

 based upon results obtained from a series of borings driven 

 around the margin of the lake and from analyses of the water, 

 also made in connection with the park condemnation proceedings. 

 The sections revealed by three of the borings, and the chemical 

 constituents of the water as determined by four different analyses, 

 are given in detail in this paper, and also a list of the genera of 

 microscopic organisms detected. 



These facts were of interest at the times when they were 

 recorded. They will be of still greater interest years hence. 

 And the visible features of today will very soon be merely 

 matters of recollection or record. 



The Silver Lake basin, so far as its natural genesis is con- 

 cerned, was formed toward the close of the Glacial Epoch, by the 

 deposition of a morainal dam across the lower or southwest 

 end of a branch of the Clove Valley. This valley, with its side 

 branches, was an ancient topographic feature which was formed 

 far back in geologic time and subsequently modified by erosion 

 of the soapstone or serpentine rock which forms the adjacent 



2 Proc. Nat. Sci. Assoc. Staten Is. i : 11. September 13, 1884. 



4 Ibid. 8: 68, 69. October 10, 1903. 



5 Ibid. 9: 11-13. February 13, 1904. 



