INDEX TO GEOLOGY OF THE NEW YORK CITY AQUEDUCT 281 



Oil-well rig, 26. 



Olive Bridge, no; site, 1 12-14; pref- 

 erable location for the proposed 

 Ashokan dam, 116. 



Oiieonta formation, 38, 55, 119. 



Onondaga limestone, 39-40, 55, 78, 

 126, 127, 129. 



Oriskany beds, 40, 55, 126. 



Orthothetes woohvorthanus, 42, 



Pagenstechers gorge, 154, 155, 159. 



Paleozoic time, 63. 



Palisade diabase, Z7, 54- 



Pebble beds, 111-12. 



Peekskill creek, 172; 



Peekskill creek valley, structure of, 



175-82; geologic cross section ana 



detail of borings, 180. 

 Peekskill granite, 52, 53, 57. 

 Peggs point, borings, 89; gorge at, 



91, 92. 

 Peggs point, crossing, S3, 97, 103. 

 Pegmatite, 53, 57, 185; dikes, 52. 

 Peneplain, Cretaceous, 67. 

 Pennsylvania borings opposite 33d 



street. New York city, 89. 

 Phyllite, 175-76, 181. 

 Physiography. 30-31, 65-74. 

 Piedmont belt, yz- 

 Platyceras dumosum, 40. 



nodosum, 41. 

 Pleistocene glaciation, 71. 

 Pliocene deposits, 36, 54. 

 Pompey's cave, 137-38. 

 Porosity tests, 142-47. 

 Porosity of Kensico rocks, 199. 

 Port Ewen beds, 40, 42, 55, 126. 

 Postglacial faulting, general ques- 

 tion of, 271-76. 

 Poughquag quartzite, 47, 56, 100, 172, 



176, 181, 272. 

 Pressure tests, 2y. 

 Pumping experiments, 142-47. 



Quartz, 202. 



Quartzite beds. 99, 100, 176. 

 Quaternary deposits, 32-36, 54. 



Raritan formation, 2>7, 54- 



Ravenswood granodiorite, 52, 53, -y;, 

 217, 220, 221, 226, 233, 252, 265, 

 269. 



Rhipidomella oblata, 42. 



Ridgway, Robert, acknowledgments 

 to, 6; department engineer, 13. 



Rondout cement, 44. 



Rondout creek, 11, 69. 



Rondout creek section, 131-35. 



Rondout siphon statistics, 141-42. 



Rondout valley section, 125-47; en- 

 gineering problems, 17-19 ; geology, 

 31; special features, 137-40; analy- 

 sis of limestones, 139; cross sec- 

 tions, 140. 



Ronkonkoma moraine, 35. 



Rosendale cement, 44, 45. 



Rosendalc limestone, 126. 



St Nicholas Park, 246. 

 Sanborn, James F., acknowledg- 

 ments to, 6 ; division engineer, 21, 



125, 149. 

 Sand, no, in. 

 Sandstones, 100. 

 Saw Mill valley, 209. 

 Schistose beds, 99. 

 Schoharie creek, 11. 

 Schoharie shale, 40, 55. 

 Sedimentation structures, 58. 

 Shales, better quality of wall than 



limestones, 140. 

 Shaw, Charles A., member of Board 



of Water Supply, 13. 

 Shawangunk conglomerate, 45, 55, 



63, 126, 127, 133, 135, 136, 149; 



thickness, 136; overthrust, 137. 

 Shawangunk mountains, 31, 127. 

 Sherburne beds, 38, 55, 109, 119. 

 Shot drill, 26. 

 Sieberella galeata, 43 ; figures, 43. 



pseudogaleata, 4S; figures, 42. 

 Siluric strata, 43-45, 55- 

 Sing Sing marble, 201. 

 Siphon line, total borings on, 141. 

 Skunnemunk mountain, 153, 154. 



