11 



INDEX. 



gn'.iuite dikes never seen in the Marquette 

 Series, 74; his methods ol' work, 71; 

 Lake Superior sandstone, always horizon- 

 tal, 100 ; no basis for Ibrniations of, 75 ; 

 on Iluroniau age of granite, 24; on indi- 

 cations of stratification, 18 ; ou Laurcu- 

 tian age of aetinolitc roek, 53 ; on 

 magnesian schists, 20 ; on origin of 

 " soft hematites," 20 ; on the original 

 state of the iron ore, 32 ; on the perido- 

 tite of Presque Isle, 75 ; on the quartz- 

 ites, 30, 31 ; origin of diorite, 20 ; plasti- 

 city of iron ore, 21; " quartzite " ol' 

 Republic Mountain, 34 ; report on the 

 iron district, 18-22; sedimentary origin 

 of iron ore, 20, 21 ; nnconformability ol' 

 the Laurentian and ITuronian formations, 

 22. 



Brooks (T. B ) and Pumpelly (R), East- 

 ern sandstone yonnger than the copper- 

 bearing rocks, 98, 99; the cojjper-bear- 

 ins; rocks conformable with the Iluronian, 

 98, 99. 



Burt, W. A., reports on iron district, 3-5. 



Calciferous formation, presence of, 103. 



Calcite, in spike-like forms, 126. 



Calcite veins, igneous origin of, 82, 83, 90. 



California, origin of placer gold of, 16, 17. 



Calumet and Hecla Jline, character of 

 copper deposit mined, 129; contact of 

 sandstone and trap at, 110 ; copper de- 

 posits of, 127 ; microscopic study of peb- 

 bles from, 118-120; sheet copper at, 

 126, 



Cambrian Age, Huronian the equivalent of, 

 13 ; of Keweenaw Point sandstone, 90. 



Canada, relations of Lanrcntian and Iluro- 

 nian in, 72. 



Canada, West, copper mines said to bo the 

 most important in America, 106. 



Cai-p River, age of rocks of, 4 ; quartzite of, 

 9 ; sandstone and quartzite of, 22, 23, 60. 



Cascade Range, iron ore and quartzite of, 

 33 ; ore and jasper of, 32, 33. 



Central Mine, a fissure vein, 129; best vein- 

 stone at, 130 ; copper deposits of, 127. 



Chamberlin, T. C.^ report of the Wisconsin 

 Geological Survey, 66. 



Champion Mine, intrusive granite at, 57 ; 

 ore of, 36 ; rocks of, 45. 



Chazy age of Keweenaw Point sandstone, 95. 



Chemist, duty of, 69. 



Chlorite, alteration product after augite, 39 ; 

 alteration product after hornblende, 56 ; 

 in quartzite, 59. 



Chlorite Schist, formed from a dike, 48; 

 occurrence of, 20, 21. 



Chocolate River, age of rocks of, 4. 



Chromic oxide, not in Presque Isle perido- 

 tite, 61. 



Chrysotile, mistaken for asbestus, 66. 



('lay, masses in sandstone, 118. 



Cleavage, no proof of stratification, 28. 



Cleaveland Mine, lamination of schist, 41 ; 

 relation of ore and schist at, 31. 



Cliff, Captain, 131. 



Cliff Mine, copper deposits of, 127 ; diabase 

 of. 111. 



Conglomerate, formation of, 84, 87,128; 

 local nature of, 122, 128 ; marks old sea- 

 beach in Ihu'onian, 31 ; of Keweenaw 

 Point, lateral moraine formations, 85; of 

 Presque Isle runtaining dolomite ])ebbles, 

 23; origin of, 122; overlying iron ore, 

 30 ; overlying peridotite of Presque Isle, 

 63; pebbles of nudaphyr at base, 115; 

 thermid water action on, 116 ; thickness 

 of, 100; copper deposited in, 83, 127- 



Conglomerate mines, mode of formation, 

 126, 127. 



Connecticut, sandstone of, 79; trap of, 81. 



Contact of diorite and schist shown in thin 

 section, 37. 



Continents, relative Ages of American and 

 European, 9. 



Cooper and Patch, Messrs., 132. 



Copper, concentration of, 92, 102, 109; 

 conditions of deposition, 130; deposi- 

 tion of, 88, 90, 92, 97. 109; deposits 

 mined for, 128, 129 ; derived from ores 

 in older rocks, 109 ; derived from tlie 

 sandstone, 81 ; description of spd<es, 126-. 

 filling joints, 126 ; finely disseminated in 

 lava, 126; in conglomerate mines, 126; 

 of volcanic origin, 76 ; originally dissemi- 

 nated in the traps, 92, 102, 109; origi- 

 nally from primitive rocks, 81 ; origi- 

 nal material brought up by the traj), 81 ; 

 mode of occurrence of, 86, 124; i)rotita- 

 ble deposits of, 76, 77 ; reduction of, 90, 

 92, 93 ; replacing melaphyr pebbles, 126 ; 

 torn from Azoic rocks by the trap, 94; 

 united to silver, 79, 81, "l05, 106, 109; 

 use of, by Indians, 92. 



Copper-bearing rocks, conformable with the 

 Huronian, 99 ; easterly dip of, 26 ; Huro- 

 nian age of, 108 ; Keweenawan age of, 

 108 ; lava flows, 86-88, 100-103, 105 ; ly- 

 ing between the Iluroniau and Potsdam, _ 

 99, 105, 107 ; of calciferous and Potsdam' 

 age, 94 ; Permian age of, 97 ; Quebec 

 age of, 94, 97 ; Taconian age of, 105 ; 

 Triassic age of, 97, 108 ; unconformable 

 to the Huronian, 105. 



Copper deposits, associated with heavy beds 

 of trap, 126; not contact fonns, 127; 

 origin of, 89, 91-95, 106, 107, 130, 131. 



