672 
INDEX, 
Oolitic limestone and sandstone, 508. 
Oolitic or argillaceous iron ore, 00, 61, 09. 
Ophileta, 28. 
Orbicula,28, 48, 103, 180, 222, 256, 461; one of the earliest 
fossils, and an existing genus, 10. 
Ore used for paint, 419. 
Organic forms, their rarity in the western waters from the 
termination of the Corniferous limestone to the commence¬ 
ment of the Carboniferous period, 514. 
Organic remains of the Chemung group, 261 ; of the Clinton 
group, 68; Corniferous limestone, 170 ; Genesee slate, 
221; Hamilton group, 195 ; Marcellus shale, 183; Medina 
sandstone, 46 ; Niagara group, 100; Onondaga limestone, 
157; Onondaga-salt group, 137 ; Oriskany sandstone, 148, 
149; Old Red sandstone, 280; Portage group, 241; Tully 
limestone, 215 ; Water-lime group, 142; not found in the 
clays of Lake Ontario, 317. 
Organic remains of the Blue limestone of Ohio, identical 
with those of the Hudson-river group of New-York, 504. 
Oriskany sandstone, general characters, 146; absence in the 
Fourth district, 146 > thickness in Pennsylvania, 147; 
organic remains of, 148, 149; locality in Ontario county, 
456. 
Orleans county, rocks of, surface, etc. 433. 
Orthis, 28, 29, 30, 71, 105, 142, 175, 180, 215, 229, 245, 255, 
256, 267, 461, 494. 
Orthoceras, 28, 29, 30, 110, 137, 180, 243, 418, 461. 
Orthonota, 76, 205. 
Orthonychia, 172. 
Oswego river, the common outlet of four lakes of the Fourth 
district, 406. 
Owen, Dr. D. D., report on the geology of Indiana, 23. 
E». 
Paint ore, 419. 
Paracyclas, 171. e 
Parallel ridges, 357. 
Pearl spar, 92, 98. 
Peat, 442, 490. 
Pecten, 264. 
Pennsylvania survey, No. 1, 27 ; No. 5, 34; No. 6, 80, 144, 
145 ; No. 7, 146 ; No. 8, 177, 184, 218 ; No. 9, 224, 251; 
No. 11, 278. 
Pentamerus, 70, 382, 422. 
Pentamerus limestone, 62, 144. 
Percival, Dr. & Prof. C. U. Shepard, survey of Connecticut, 
23. 
Petroleum, 168, 497, 498. 
Philipsburgh, rocks at, 486. 
Pholas costata, a bed of the shells found at New-Bedford, 
but the species not now known in a living state, 9. 
Physical advantages of New-York, 410. 
Physical features of the Fourth district, 405. 
Pinnopsis, 243. 
Planorbis, 361, 396, 479. 
Plaster or gypsum beds, 121 - 125. 
Plaster, its action on vegetation, 430. 
Pleurorhyncus, 171. 
Pleurotomaria, 28, 29, 48. 
Ponds, 169, 170. 
Porites, 86, 91. 
Portage falls, 368 ; lower falls, groundplan of, 37. 
Portage or Nunda group, general characters of, 224; sub¬ 
divisions. 226 ; diagonal lamination, 230 ; ripplemarks, 
230; casts of shrinkage cracks, 230; concretions, 230; 
casts of flowing mud, 232; casts of mud-furrows and 
striae, 231 ; localities, 234; thickness, 238; minerals and 
springs of, 239; agricultural characters, 239; organic 
remains, 241 ; localities of superposition, 248 ; summit of, 
260; local details of, 452, 457, 458, 467, 473, 477, 480, 
484, 488, 494. 
Portage group equivalent of Waverley sandstone, 501. 
Posidonia, 72. 
Potholes, 376. 
Potsdam sandstone, 27. 
Prairies, 321. 
Primary or Hvpogene system, 17. 
Protean group, 58, 80. 
Protozoic rocks, the first great division, 24. 
Pseudomorphous or hopper-form crystals and cavities, 127. 
Pterinea, 29, 30, 172, 229, 254. 
Pyrites, 477 ; see Iron pyrites. 
Pyritiferous rock, 177, 184. 
45 . 
Quantity of water flowing down the Niagara river, 401. 
Quarries, 38, 451, 460, 478, 488, 492, 497. 
Quartz crystals in Calciferous sandrock, 28 ; in Clinton 
group, 67; in Onondaga limestone, 153, 157, 168. 
Quaternary system, 19. 
Queenston heights, 384. 
Quicklime, 84, 85, 88, 420, 438, 467; and hydraulic cement, 
431. 
Quicksand, 346. 
IS. 
Rapids between Lake Erie and Niagara falls, 400. 
Ravines of Chautauque county, 253 ; in the Hamilton group, 
451; at the head of Canandaigua lake, 457. 
Recession of falls, 378; of Niagara falls, 391, 398. 
Red and variegated shales and sandstones of Pennsylvania, 
58. 
Red marl and sandstone, 34. 
Red marly and shaly sandstone, 36. 
Red sandstone of Oswego, 34. 
Red shale of the Onondaga-salt group, 119. 
Red shale and sandstone, 38. 
Relative elevation of Northern and Western New-York, 335. 
Relative ages of modern deposits, 342. 
Remarks preliminary to the rocks above the Tully limestone, 
217. 
Rensselaer School, establishment and objects of, 6. 
Resources of the northern counties, 498 ; of the southern, 
498. 
Rhomb spar, 134. 
