408 proceedings of the academy of [1889. 



December 3. 



The President, Dr. Joseph Leidy, in the chair. 



Forty-five persons present. 



A paper entitled " On the Modification of the Apex in Murex," 

 by Frank C. Baker was presented for publication. 



Notes on the drift on Block Island. — Mr. Theo. D. Rand remarked 

 that this island, lying in the Atlantic Ocean off the extreme east- 

 erly point of Long Island, shows the drift formation as he had seen 

 it nowhere else. The shores in many parts rise from the ocean as 

 precipitous bluffs to a height from one hundred to two hundred feet. 

 The outer surface is constantly eroded while the summits are pre- 

 served by a growth of grass generally too high above the water for 

 drifting sands to cover. Thus excellent sections are exposed. 



The island is pear-shaped, about seven miles from north to south 

 and between three and four from east to west at its widest point 

 which is probably a mile and a half from its southern edge. 



There is not a creek or running water of any kind on the island 

 except a few springs bordering the ocean, neither is there a valley 

 strictly so called. The whole island is made up of rounded hills 

 and bowl-like depressions, the bottom of the latter usually occupied 

 by a fresh-water pond, in many of which flourish water lilies of 

 remarkable size and beauty. Most of it is covered with a soil of 

 sand, clay and gravel which seems to be quite fertile. 



Here and there are boulders ranging down from two thousand 

 cubic feet (visible above ground), but the stone fences, which every- 

 where divide the farms often into quite small fields, testify that man's 

 industry has removed many thousands from the surface. 



The island has been described as pear-shaped, but a little north 

 of the middle of the pear is a brackish pond of more than a 

 thousand acres in extent, with but a narrow isthmus of sand separat- 

 ing it from the ocean on the east and on the west. On the west 

 this isthmus has been dredged through and the tide now flows in 

 and out. On the east the isthmus is not over one hundred yards 

 wdde and not over, probably, five or ten feet above high tide. 

 North of this isthmus the ground gradually rises to high bluffs. 

 South and southwest of it almost all the land is elevated, the 

 extreme height being some three hundred feet at Beacon Hill. 



On examining the bluffs it would appear at first sight that erosion 

 is progressing with great rapidity, as along most of the bluffs large 

 boulders line the shore and extend a considerable distance seaward 

 forming a breakwater. The cause of this was not at first apparent. 

 With few exceptions the bluffs were clothed with grass to their 

 extreme edges. The descent from the edge was generally precipitous 



