(icuh)ilil vf l\icli inniid Cninihi. X. V. 17o 



metamorpliic rocks alreudy described us lying just northciist of 

 the chtys, \\a\Q furnislied some if not nil of the material for their 

 formation. These rocks lie immediately between the Triassic 

 and Cretaceous, and were })robably very much higher in those 

 epochs than they are now, for they formed in part tlie southeast- 

 ern boundary of the Triassic sea. 



The decomposition of the gneiss would i)roduce the nuiterials 

 composing the strata of sand and clay which Avere deposited in 

 basins along the coast, the strata lying nearest to the rocks 

 being first deposited. 



Where the Cretaceous formation is not covered ))y glacial 

 drift, there is now living on it a i)ecnliarly southern vegetation. 

 J have called attention to this fact in the Bulletin of the Torrey 

 Botanical Club, VII, 81. by showing how the characteristically 

 southern flora of -the ISTew Jersey pine-barrens extends into 

 Richmond and Suffolk Counties, N. Y., hue only on the sands 

 of the Yellow Drift. 



Qi'ATEHXA in" Epoch. 



GUirial Drift.- — Deposits of material brought from the north 

 by the ice of the glacial ej)och. are found over the greater part 

 of Staten Island, but do not entirely overspread it. 



The nujst southern terminal glacial moraine crosses Staten 

 Island from the Narrows to Tottenville, and is distinctly marked 

 by a continuous line of hills, the size and appearance of which 

 have been already described. These hills mark the farthest 

 southern extension of the ice-sheet, and the line along which 

 the glacier deposited most of its burden of boulders, pebbles, 

 sand and chi}', which it had torn irom the rocks in its south- 

 ward journey. In many places these hills have the peculiar 

 lenticular form which they assume on Long Island and in the 

 Eastern States. The dotted line on the map extending west- 

 wardly from Clifton and ending at Tottenville, represents the 

 most southern and eastern position of the boulder-drift on 

 Htaten Island, and has been quite accurately determined. The 

 moraine has been partially removed by the wash of the waves 

 from Prince's Buy northward to near the Great Kills, leaving a 

 bluff of variable height. 



