11 



INDEX. 



granite dikes never seen in the Marquette 

 Series, Ti; his methods of work, 71; 

 Lake Superior sandstone, always horizon- 

 tal, 100; no hasis for formations of, 75 ; 

 on lluronlan age of granite, 2'i ; on indi- 

 cations of stratification, 18; on Lauren- 

 tian ago of aetinolite 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 Presqne Isle, 75 ; on the quartz- 

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

 city of iron ore, 21; "quartzitc" of 

 Kepublic Mountain, 34; report on the 

 iron district, 18-22; sedimentary origin 

 of iron ore, 20, 21 ; nnconformahility of 

 the Laarentian and lluronian formations, 



23. 

 Bj'ooks (T. 13.) and Pumpelly (R), East- 

 ern sandstone younger tlian the copper- 

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

 ing ro(dis conformable with the Huronian, 



98, 99. 

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



Calcifeuous formation, presence of, 103. 



Calcite, in spike-like forms, 120. 



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



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



Calumet and ITccla Mine, 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, Hui'onian the equivalent of, 

 13 ; of Keweenaw Point sandstone, 90. 



Canada, relations of Lanrentian and lluro- 

 nian in, 72. 



Canada, West, copper mines said to be the 

 most important in America, 106. 



Car]) River, age of I'ocks of, 4 ; quartzite of, 

 9 ; sandstone andquarizite of, 22, 23, GO. 



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. 



Chnmberlin, 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, 09. 



Chlorite, alteration product after angitc, 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 Presquc Isle pcrido- 



tite, 61. 



Chrvsotile, mistaken for asbestus, 66. 



(Uay, masses in sandstone, 118. 



Cleavage, no proof of stratilication, 28. 



(Jleaveland Mine, lamination of schist, 41 ; 

 relation of ore and seliist at, 31. 



Clilf, Captain, 131. 



Cliff Mine, copper deposits of, 127 ; diabase 

 of, 111. 



Cotiglomeratc, formation of, 84, 87,1.28; 

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

 beach in Muronian, 31 ; of Keweenaw 

 Point, lateral moraine formations, 85; of 

 Presqoe Isle containing dolomite pebb.les, 

 23; origin of, 122; overlying iron ore, 

 30 ; overlying peridotite of Presque Isle, 

 63 ; pebbles of melaphyr at base, 115 ; 

 thermal 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 dlorite 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 the 

 sandstone, 81 ; description of spikes, 126; 

 liUIng joints, 126 ; fmely 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 tra]), 81 ; 

 mode of occurrence of, 86, 124; profita- 

 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, 105, 106,109; 

 use of, by Indians, 92. 



Copper-bearing rocks, conformable with the 

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

 nian age of, 108 ; Kcweenawan age of, 

 108 ; luvallows, 86-88, 100-103, 105 ; ly- 

 ing between the lluronian and Potsdam, 

 99, 105, 107 ; of calcifcrous and Potsdam 

 age, 94 ; Permian age of, 97 ; (^uebee 

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

 Triassle age of, 97, 108 ; unconformable 

 to the lluronian, 105. 



Copper deposits, associated with heavy beds 

 of trap, 126; not contact forms, 127; 

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



