1884.] NEW YORK ACADEMY OF SCIENCES. 29 



of laminated yellow sands over the cretat-eons beds at Glen Cove. 



The Pre-ylacial Drift of Siuten Island is for the most part 

 concealed by the moraine and the modified Glacial Drift result- 

 ing from the wash of the morainal deposits ])y the sea during 

 periods of depression accompanying or succeeding the ice 

 period. I liave noticed it well exposed for study in but four 

 localities : on Todt Hill, at Prince's Bay Light-house, south-east 

 of Tottenville, and about Kreischerville. 



The Todt Hill exposure is of great interest. The sand and 

 gravel here reach the thickness of six feet in places, and vary 

 from this depth to a layer of scattered yellow pebbles. The 

 area here covered amounts to several acres, and the elevation 

 above tide is about two hundred feet, indicating a depression of 

 more than that amount dm*ing its deposition, and the almost 

 complete submergence in the island at the time. It is here 

 almost entirely made up of gravel, some of the stones reaching 

 two inches in diameter, but there is also sand, and I have re- 

 cently seen a single l)and of a drab-colored clay. The deposit 

 is stratified throughout, and very irregularly so, cross-bed ding- 

 being prominent. The immediate underlying material is limo- 

 nite, on which it rests unconforma])ly, and fragments of this 

 material are to be found in the gravel. Howevei-, the deposi- 

 tion of the iron oxide went on after that of the gravel to a cer- 

 tain extent, for the peculiar conglomerate formed by the 

 cementation of the latter by the former material is to be found 

 in small quantity in the gravel beds. I am inclined to believe 

 that the epochs of deposition of the two were innnediately con- 

 secutive. In a former paper on the Geology of Staten I.-^land,* 

 I suggested that the gravel deposits here descril)ed might per- 

 haps be referred to the modified Glacial Drift, their position im- 

 mediately south of the moraine giving rise to this impression. 

 At that time I was not familiar with the Pre-glacial Drift, and 

 my idea there stated is erroneous. The limonite rests im- 

 mediately on the serpentine rock, which fomns the entire range 

 of high hills of Staten Island. 



On Todt Hill, as elsewhere, the Pre-glacial Drift contains- 

 pebbles with palaeozoic fossils poorly preserved. I have here 

 found crinoid stems, a Fenestelta, a J^'avosite, and one or two 

 Brachiopods. The gravel is used in road-making, and the 



* Annals of this Academy, ii, No. 6, p. 175, 1881. 



