GEOLOGY OF THE NEW YORK CITY AQUEDUCT 257 



218 South side of Hester street east of Norfolk street 

 Surface elevation 31 feet 



Rock floor at el. -183 feet 

 No core recovered in upper 300 feet 



Interbedded limestone in Fordham gneiss below el. -550 feet 

 to bottom 



yj Hester street near Suffolk \^sce 202] 

 202 Hester street west of Suffolk 

 Surface elevation 30.5 feet 



Rock floor -99.5 feet. Rock all decayed to great depth 

 Manhattan schist to -470 feet 



Fordham gneiss -470 feet to bottom at -577 feet 

 Believed to cross fault plane 

 213 Hester street 85 feet east of Suffolk street 

 Surface elevation 33.3 feet 

 Rock floor at el. -i 16.7 feet 



The rock is Fordham gneiss of the black and white banded 

 type, with dips varying from 30° to 80^. For a very short 

 distance at el. -275 feet dips of io'^-i5° were recorded 

 Core recovery very good 



II Hester and Clinton streets 



Rock floor -204 feet. Badly disintegrated and no core to -279 

 feet. Unusual rock, identified as a mica schist of obscure 

 structure (not typical). Some calcareous portions. 

 At first this was thought to belong to the Manhattan formation, 

 but it is probably a schistose and rather unusual f acies of the Ford- 

 ham series. This hole was subsequently reoccupied and deepened 

 as no. 220 under another contract with the result that an inter- 

 bedded series of gneisses and limestones was shown to a total final 

 depth reaching el -660 feet. Rock cores indicate dip of about 60°. 

 201 Clinton street between east Broadway and Henry street 

 Surface elevation -31.3 feet 

 Rock floor -133.7 feet 



A schistose variety of Fordham gneiss with associated inter- 

 bedded limestone 



219 Northwest corner of Clinton and Madison streets 

 Surface elevation 26 feet 



Rock floor at el. -214 feet 



Fordham gneiss and interbedded limestone 



Good core recovery below el. -400 feet 



