460 
Porphyry, Quartzless, Localities for, 93. 
—— of National mine, 94. 
——, Phases of, 91. 
——, Relation of, to augite-syenite, 92. 
—— Silica content of, 92. 
——, Tabulation of observations on, 94, 95. 
Portage Bay Island and vicinity, 296-298. 
———-—, Animikie Group on, 297. 
————— , Diabase-porphyrite of, 78, 85, 297. 
Portage Lake, Amygdaloids of, 189, 345. 
——, Amygdaloids (cupriferous) of, 421, 422. 
——, Conglomerates of, 93, 190-192. 
——, Copper deposits of, 420-422. 
——, Dip of strata on, 187. 
——, Nonesuch Shale belt on, 193. 
——, Sandstone of, 130, 131, 185, 192, 193. 
—-—, Thinning of beds on, 187. 
——, Upper Division on, 153, 193. 
Portage Lake Section, 188-195. 
———, Conglomerates of, 32, 190, 191. 
———, Exposures of, 188. 
———, Great Conglomerate of, 191, 192. 
——-—, Marvine on, 188. 
———, Pumpelly on, 188-190, 194. 
———, Sandstone of, 192, 193. 
——-—, Shales of, 192, 193. 
——-—, Stratigraphy of, 189. 
———, Summary of, 194, 195. 
———, Thickness of, 188. 
———, Upper Division on, 192, 193. 
Potato River Section, 230, 231. 
——-—, Diabases of, 74, 83, 231. 
——~—, Felsitic porphyry of, 103, 106, 231. 
———, Gabbros of, 45, 231. 
Potsdam Sandstone of New York, Relation of, to Keweenaw 
Series, 443-445. 
———-—, Western «quivalents of, 442, 445. 
————. See Cambrian, Sandstone. 
Powell, J. W., Publication of, 431. 
—,on Tertiary and Keweenawan eruptives, 436. 
Praysville, Diabase-porphyrite of, 81, 176, 177. 
Presq’ Isle River, Diabase of, 212. 
— ——, Limits of Porphyry on, 212. 
———, Lower Division on, 208. 
———~, Nonesuch shale belt on, 223. 
——-—, Outer sandstone exposed on, 220. 
—— —, Outer trap exposed on, 219. 
———, Upper Division on, 220. 
Prehnite in amygdaloids, 89, 90. 
—— olivine-diabase, 71. 
—— olivine-free diabase, 65. 
----— (amygdaloidal), 64. 
— — pseudamygdaloids, 62-66. 
Pyroxene. See Augite. 
Pumpelly, R.., 2, 5, 7, 10, 163. 
— on amygdaloids, 88, 89, 135, 136, 416. 
———, copper in, 421, 422. 
——-— of melaphyrs, 87. 
——augite-diorite, 56. 
—— ashbed-diabases, 61. 
—-— basic original rocks, 135. 
—-— Calumet Conglomerate, 195. 
--— conglomerates, pebbles of, 31. 
—— Des Cloizeanx’ method, 39. 
—— diabases, origin of, 11. 
—— diabase-porphyrite, 77, 83, 235. 
INDEX. 
Pumpelly on Eastern Sandstone, relation of to Keweenaw 
Series, 360, 362, 363. 
—— granitic porphyry, 110. 
——hornblende-gabbro, 56. 
—— Keweenawan sandstones, nature of, 30. 
—— Keweenaw Series, age of, 13. 
——-——, relation of, to Huronian, 106, 107. 
—— melaphyr, 68-70. 
—— olivine-diabase, 68-71, 73, 74. 
— — olivine-free diabase, 60-66. 
—— ‘ordinary ” diabase, 61. 
—— orthoclase-free gabbro, 45. 
—— orthoclase-gabbro, 53, 54. 
——the Porcupine Mountains, 207. 
——— Portage Lake Section, 188, 189. 
—— Pre-Cambrian erosion of Keweenawan rocks, 363. 
—— pseudamygdaloids, 60-66, 135. 
—, Publications of, 21, 22, 23. 
—onrocks of Saint Croix Valley, 239. 
Quartz of amygdaloids, 89, 90. 
——augite-syenite, 112, 113, 114. 
——diabase-porphyrite, 79. 
—— granitic porphyry, 112, 113, 114. 
— (secondary) of felsites, 99, 100, 211, 438. 
——, Fenqué and Lévy on, 438. 
—— of orthoclase-gabbros, 51. 
——— augite syenite and granitell, 113, 114, 438, 
——— quartzless porphyry, 92, 438. 
— of hornblende-gabbro, 57. 
—(porphyritic) of quartz-porphyry, 93, 102. 
Quarzites, Animikie, 367-386. 
—, Huronian, 386-388. 
Quartz-porphyry. See Felsites and Porphyry, Quartz-. 
Quartzless porphyry. See Porphyry, Quartzless. 
Rainy Lake, Schists of, 397. 
Red River Road, Animikie Group on, 380. 
Red Rock Bay and vicinity, Beaver Bay Group at, 320. 
———-—, Diabase-porphyrite of, 85, 323. 
———-—, Dike near, 322, 323, 436. 
———~—, Felsites of, 322. 
————, Gabbro of, 322. 
———-—, Quartz-porphyry of, 103, 110, 322. 
Red Rock Post, Gabbro of, 333. 
Report of Geological and Mineralogical Survey of Mineral 
Lands of United States in Michigan. See Foster and 
Whitney. 
Rice Point Quarry, 119. See Duluth. 
Rivot, L. E., 5. 
—on origin of traps, 10. 
—, Publication of, 18. 
Roche de Bout, Diabase of Island near, 338. 
Rockland (National mine), Quartzless porphyry of, 94. 
Rocky Run River, Sandstone of, 249. 
Rogers, W. B., Publication of, 15, 19. 
Rominger, C., 5. 
— on Eastern Sandstone, age of, 352. 
—— Keweenaw Series, age of, 12. 
—, Publications of, 21, 22. 
Rosenbusch, H., on augite-syenite, 115. 
—— basalt, 37. 
—, Classification of plagioclase-augite rocks by, 35. 
-—, Nomenclature of rocks adopted, 28. 
—, Nomenclature of felsites, 96. 
Rutley on quartz-crystals in quartz-porphyry, 101. 
Saganaga Lake, Schists of, 397. 
St. Croix, Dalles of, Diabase-porphyrite of, 235, 236, 
