INDEX, 
, 
Orthoclase-free diabase (coarse grained). See Gabbro, Ortho- 
clase-free. 
Orthoclase-gabbro. See Gabbro Orthoclase. 
Orthoclase-free gabbro. See Gabbro, Orthoclase-free. 
Osceola, Contact of Keweenaw Series and Potsdam Sandstone 
in, 236, 287. 
Otter Head, Huronian of, 400. 
Owen, D. D., 5, 37, 403. 
—on Fastern Sandstone, 351. 
—— Keweenawan rocks, 112. 
——St. Croix Sandstone, 411. 
——, Publications of, 17. 
—. See Norwood. 
Owen, R., on Pigeon River dikes, 370, 371. 
Pebbles in augite-syenite, 112. 
—of Albany and Boston Conglomerate, 94, 190, 191. 
—— Calumet and Hecla Conglomerate, 105, 195, 196. 
—— National mine, 94, 190, 191. 
Peninsula Bay, Trap of, 401. 
Penokee Huronian, 391, 392. 
Percival mine, 257. 
Petit Marais, 264. 
——, Temperance River Group at, 323. 
Phenix Mine Group, 175, 176, 178. 
Physical Geology of Lake Superior. See Whittlesey. 
Pic Island, Trap of, 401. 
Pie, The, 415. 
Pic River, Huronian of, 401. 
Pie Island, 331. 
Pigeon Bay, Animikie Group on, 372-374. 
——, Dike-rock from, 372. 
——, Gabbros of, 372. 
Pigeon Point, Animikic Group at, 369, 370. 
Pigeon River, 414. 
——, Acid eruptives of, 372. 
—— Animikie Group on, 370-372. 
—-—, Dikes on, 371. 
——-—, Rocks of, 372. 
——, Gabbros of, 371, 372. 
Pike Lake, Gabbros of, 274. 
Pike River, Slates of, 401. 
Pine Rapids, Sandstone of, 249. 
Plagioclase of amygdaloids, 88. 
——augite-syenite, 113. 
— — hornblende-gabbro, 57. 
—— olivine-diabase, 69. 
—— olivine-free diabase, 63. 
——orthoclase-free gabbro, 39, 40. 
——-—, Angles of, 39, 40, 439. See also Tabulations of obser- 
vations of various rocks. 
Point Magnet, 334. 
Pointe aux Mines, 347, 349, 415. 
Pokegoma Falls, Animikie Group at, 383, 384. 
Poplar River, Rocks of head-waters of, 145, 272. 
——, Temperance River Group on, 328. 
Porcupine Mountains, 65, 206-224. 
——, Authorities on, 207. 
—— Basic Belt of, first, 214-218, 432, 435. 
————, second, 219, 220. 
——— belts, continuation of, 224-226. 
——at Carp River and Little Carp River, 215-217. 
——, Diabase-porphyrite of, 82, 215, 440. 
- ——, Dike of, 253. 
——, Fault of, 219. 
—-—, Felsites and quartz-porphyries of, 99, 102, 103, 105, 106, 
343, 150, 209-214. 
459 
Porcupine Mountain, Formation of, 206. 
——, Height of, 209. 
——, Lower Division on, 209. 
——, Melaphyr of, 214. 
—-—, Nonesuch shale belt in, 221-224. 
——, Olivine-diabase of, 72, 74, 214. 
——, Olivine-free diabase of, 67. 
——, Porphyry of, 150, 209-212, 432, 433. 
————, Central, 208, 209. 
———-—, Distribution of, 210-212. 
— ———, Limits of, 212-214. 
——, Sandstone of, 131, 132. 
--—-—, Inner, 217, 218. 
———, Outer, 220, 224. 
——, Stratigraphy of, 208, 209, 413. 
——, Townships 50 and 51, R. 42 W., Conglomerates of, 217. 
——, Upper Division on, 153, 209. 
Pork Bay, Temperance River group at, 324. 
Porphyrite, Diabase. See Diabase-porphyrite. 
Porphyries. See Acid original rocks. 
Porphyry-conglomerates. See Conglomerate, Porphyry. 
Porphyry, Felsitic. See Felsites. 
Porphyry, Granitic, of Albany and Boston Conglomerate, 118, 
119, 190, 191. 
——-—Baptism River, 123, 272. 
——— Beaver Bay, 122, 306. 
——— Béte Grise Bay, 117. 
——— Duluth, 119, 270, 271. 
——— Eagle Mountain, 124, 273, 274. 
—-—— — River conglomerate, 118, 168. 
——— Maw-ske-quaw-caw-maw River, 123. 
——— Minnesota, T. 56, R.7 W., 122. 
——— Mount Bohemia, 116, 184. 
——near Split Rock River, 121. 
——— Tischer’s Creek, 120. 
See Augite-syenite. 
—, Quartz, near Baptism River, 110, 318. 
——of Beaver Bay, 106-108, 307. 
— —— Bead Island, 111, 346. 
——— the Calumet Conglomerate, 105, 195, 196. 
——— Cedar Island, 108, 306, 307. 
———Eagle River Conglomerate, 104, 165. 
——— Grand Marais, 110, 391. 
— —— Great Palisades, 109, 314-818. 
——— Little Carp River, 106, 210. 
——— Michipicoten Island, 112, 346, 
——— Potato River, 106, 231. 
——— Porcupine Mountains, 42, 51, 105, 210, 211. 
— ——Red Rock Bay, 110, 322, 323. 
——— Stannard’s Rock, 197, 198. 
———Torch Lake Railroad, 104, 196. 
——— Tyler's Fork, 106, 
See Felsites. 
—, Quartzless, 91-95. 
—— of Albany and Boston Conglomerate, 94, 190, 191. 
—-—, Base of, 92. 
—— of Bead Island, 95, 304. 
———Brunschweiler River, 95. 
——, Characteristics of, 91, 92 
——, Color of, 92. 
— —, Constituents of, 92, 98. 
——-—, augite, 93. 
——-—, feldspars, 92, 93. 
——-—, quartz, 92, 438. 
—— of Duluth, 95. 
— —, Flowage structure in, 93. 
