928 
INDEX. 
Page. 
Pigeon  slate,  character  and  distribution  of.  68G,  687 
Pikes  Peak,  rocks  of 802, 807 
Pikes  Peak  granite,  character  and  distribu- 
tion of 45, 805, 808, 811 
Pikes  Peak  quadrangle,  rocks  of 805-800,828 
Pilot  Knob,  ores  of 734-735,737 
rocks  of 737-741 
Pinal  Creek,  rocks  on 772 
Pinal  Mountains,  rocks  in 772 
Pinal    schist,     character    and    distribution 
of 45, 77G,  777 
correlation  of 45, 777-778 
Pine  Bluff,  rocks  at 722 
Pine  Bluff  quartz  porphyry,  character  and 
distribution  of 722 
Pine  Island,  rocks  of G31 
Pine  River,  rocks  on 148, 174, 189, 332 
Pihon  Range,  rocks  of 40, 794 
Pipestone,  fossils  at 725 
quarries  of 19G 
Pipestone,  Lake,  rocks  of 532 
Pipestone  Creek,  rocks  on 724-725 
Pipestone  Rapids,  rocks  at 23G 
Pirsson,  L.  V.,  and  Weed,  W.  IT.,  on  Montana 
rocks 856-857, 898 
Placentia  Bay,  rocks  on 51G 
Placid,  Lake,  rocks  of G13 
Pleasant  Hill,  rocks  at 67G 
Plumbago  Canyon,  rocks  in 845 
Plumbago  Creek,  rocks  on 123, 134, 385 
Plummerargillite,  character  and  distribution 
of 410 
Plymouth,  rocks  at 5G1 
Pochuck  gneiss,  character  and  distribution 
of 644,645 
Pogonip  Range,  rocks  in 4G,  794, 800 
Point  aux  Mines,  rocks  at 257, 259 
Point  Isabelle,  rocks  at 1 12 
Point  Lake,  rocks  near 526 
Pokegama  Falls,  rocks  at 202, 214, 237, 238, 306 
Pokegama  quartzite,  character  and  distribu- 
tion of 222, 238, 244-245, 339 
correlation  of 220, 328-329, 409 
Pompton,  rocks  at 638, 639 
Ponds  Bay,  rocks  of 529 
Poohbah,  Lake,  rocks  near 275, 280 
Poplar  Lodge,  rocks  near 297 
Poplar  River,  rocks  on 189, 198 
Popolopen  Pond,  rocks  at 631 
Porcupine  Mountains,  rocks  of 110, 
113, 175, 183, 298, 300, 303, 304 
Portage  Bay  Island,  rocks  of 198 
Portage  Lake,  rocks  near 112-113, 
120,125,163,301,304 
Port  Arthur,  rocks  at 287,293,351,358,372 
Port  Clarence  limestone,  character  and  distri- 
bution of 889 
correlation  of 891 
Port  Coldwell,  rocks  of 291 
Port  Henry,  rocks  at 600, 607 
Porthill,  rocks  near 849-850, 852, 880 
Port  Kent,  rocks  at 600 
Portland,  rocks  at 552, 553, 717 
Portland  group,  character  and  distribution  of.      491 
correlation  of 491, 498 
Portland  quartzite,  correlation  of 721 
Page. 
Port  Neuf  Canyon,  rocks  in 782 
Potato  Creek,  rocks  on 808 
Potato  River,  rocks  on 184 
Potomac  River,  rocks  on 668 
Potsdam,  rocks  near 610, 840 
Potsdam  district,  location  and  character  of. .      218 
Potsdam  sandstone,  character  and  distribu- 
tion of 118, 136-137, 180, 183, 
192, 190, 198, 231, 211, 213, 218, 25G,  273, 
300, 301, 307-308,  603,  C07, 610, 614,  G5G, 
658,  675,  685,  692,  717-719,  723,  727-728 
correlation  of 116,182, 
197, 198, 200, 205, 208, 240, 250, 255, 
313-314, 363-365, 3C8,  5G2, 5G5, 624 
relations  of 65, 101, 182-183, 
188, 419-420, 448, 449, 468, 516, 518, 
529,  600,  623, 637,  657,  659,  722-724 
See  also  Eastern  sandstone. 
Poughquag,  rocks  near 627, 628 
Poughquag  quartzite,  character  and  distribu- 
tion of 
correlation  of 633,  C34 
Poverty  Gulch,  rocks  in 811 
Powell,  J.  W.,  on  Grand  Canyon  rocks 771-773, 
891,892 
on  Uinta  Mountains  rocks 779-780, 893 
Pownal  Mountain,  rocks  of 567 
Prairie  River,  rocks  on 202 
Prairie  River  granite,  character  and  distri- 
bution of 222-223 
Pratt,  J.  H.,  and  Lewis,  J.  V.,  on  North  Caro- 
lina corundum 683, 715 
Pre-Cambrian  rocks,  characteristics  of .  18-19, 57-58 
correlation  of 40-41 
definition  of 16, 25, 29 
distribution  of 16-17, 41-47, 102 
in  America,  map  showing Pocket. 
map  showing,  description  of 102 
in  foreign  countries 47-58 
in  Lake  Superior  region,  map  show- 
ing       330 
fossils  in 19, 96, 349 
intrusives  in 380-382 
iron  in 51 
knowledge  of 17-18 
metamorphism  of 19 
nomenclature  of 58-63 
structure  of 17 
subdivision  of 13, 19-25, 40, 155, 268, 32G 
difficulties  of 24-25 
in  foreign  lands 47-58 
See  also  Archean;  Algonkian. 
Pre-Cambrian  shield,  knowledge  of 17 
location  of 16, 545 
Presque  Isle,  rocks  at  and  near 109, 
110,112,116,125,129 
Pretts,  W.  W.,  on  Fox  River  rocks 722, 750 
Priest  River,  rocks  on 850 
Primal  series,  character  and  distribution  of. .     119, 
654-655, 675 
relations  of 657 
Primary  rocks,  character  and  distribution 
of 108-109, 
114, 254, 403, 448, 490, 504, 514, 552, 
558-560, 582, 583, 598-599, 623-626, 
664, 673, 676,  688,  691,  694,  717, 868 
