INDEX. 



VU 



Lithologista who have studied Lake Supe- 

 rior rocks, 74. 



Litholojfv, defects of its methods, 74 ; of 

 irou district, 2, 7- 



Limcstoue, associated with serpentine, 66. 



Limonilc, botrvoidal ore of Peudill Mine, 

 51. 



Liiigulffi in sandstone, 20. 



Locke, J., on Pn-sque Isle serpentine, 62; 

 nietamorphic origin of Keweenaw Point 

 rocks, 7y, 80 ; on quartz veins, 6. 



Logan, W. E., on the Calciferous and Pots- 

 dam age of the copper-bearing rocks, 94 ; 

 Cambrian age of sandstone, 90 ; confusion 

 of Azoic with copper-bearing rocks, 91 ; 

 eastern sandstone of Chazy age, 94 ; er- 

 roneous statement of Houghton's views, 

 83 ; sandstone older than Potsdam, 83. 



McCoMBER Mine, minerals of, 51 ; geologi- 

 cal structure of, 51. 



Macfarlaue, T., maintains the Permian age 

 of the Lake Superior sandstone, 94 ; op- 

 poses Selwyn's views, 106. 



Magnetite, octahedrons of, 30, 33 ; caught 

 up by a dike, 45 ; dikes of, 36 ; altered to 

 hematite, 39 ; network form of, 66 ; 

 produced in the alteration of olivine, 61 ; 

 surrounded by hematite films, 48 ; rec- 

 tangular network of, 61; its relations to 

 martite, 34, 33. 



Maine, trap of, 81. 



Malachite on Keweenaw Point, 76. 



Manganite at McComber Mine, 51. 



Marcou, J., on the igneous origin of copper, 

 90 ; maintains the New Red age of the 

 Lake Superior sandstone, 90 ; copper 

 veins dike formations, 90. 



Margarophyllites in garnet, 53. 



Marquette, dikes near, 36, 37, 38 ; sand- 

 stone of, 60. 



Marquette region, Laurentian and Huro- 

 nian in, 22 ; stratigraphy of, 19 ; iron ore 

 in, 6, 7 ; sediuentary rocks of, 74, 75. 



Masonite microscopically like ottrelite, 45. 



Massachusetts, Eastern, geological methods 

 followed in, 72. 



Martite, relations to magnetite, 34, 35 ; 

 octahedrons of, 33. 



Marvine, A. R., on the formation of the 

 copper-bearing veins, 103 : on the con- 

 centration of the copper in the veins, 102 ; 

 his geological observations sustained, 131 ; 

 relation of trap and sandstone. 111 ; on 

 conglomerate beds, 100 ; origin of amyg- 

 daloid structure, 100, 101 ; supports the 

 views of Foster and 'Whitney, 103 ; his 

 report on copper-bearing rocks, 100-103 ; 

 on metamorphism, 101, 102. 



Mclaphyr, an altered basalt. 111 ; dikes of, 

 at Coppper Falls Mine, 111, 112; fre- 

 quently mined on Keweenaw Point, 111 ; 

 glassy material formerly in, 125, 126 ; 

 impregnated with copper, 130; locally lim- 

 ited, 128 ; microscoi)ic examination of, 

 from junction with jasper, 44; micro- 

 scopic study of, from Washington Mine, 

 43 ; pebbles of, replaced by copper, 126; 

 fit Portage Lake, 94 ; relation of first lava 

 flow to underlying sandstone, 114, 115; 

 richer in copper near a vein, 125. 



Menominee district, granite of, 24, 71; 

 iron ore in, 3, 6, 7 ; Laurentian in, 22; 

 Huronian rocks of, 22. 



Melamorphic rocks, origin of, 3, 5, 6, 7, 8, 

 9, 10, 11, 14, 15. 



Metamorphism, the agent of, 35 ; of ciystal- 

 line rocks, 8, 9, 14, 15 ; exciting cause 

 of, 27 ; of traps and sandstones, 101, 102 ; 

 of schists, 26. 



Mica, in nrgillaceous sandstone, 116; sec- 

 ondary origin of, 38 ; greenish, ill quartz 

 rock, 49. 



Michigan geologists, defective methods of, 

 118. 



Microclinc in granite, 57. 



Microlites, of apatite, 37 ; in feldspar and 

 quartz, 56 ; in quartz, 38, 44. 



Microscope, use of, in the study of rocks, 73, 

 74. 



Microscopic analysis, insuflBcient to prove 

 origin of rock, 43. 



Microscopic distinction between lava flows 

 and intrusive rocks. 111. 



Microscopic examination of Lake Angeline 

 diorite, 42. 



Mineral Point Railroad, microscopic study 

 of pebbles from, 120. 



Mining, destructive of geological evidence, 

 68. 



Montalban series in the iron region, 24. 



Mud-flows in shale, 121. 



Jliiller, A., copper reduced by organic mat- 

 ter and oxide of iron, 92. 



JIurray, A., Huronian age of iron district, 

 13. 



Muscovite, cutting biotite, 56 ; folia of, in 

 feldspar, 57 ; in feldspar, 56. 



Negaunee, Michigan, eruptive diorite at, 

 41 ; "soft hematite" mines of, 51. 



Nevadite, 72. 



Nc\v England, methods of observation in, 73. 



New Jersey, sandstone of, contemporaneous 

 with that of Keweenaw Point, 79. 



New Red sandstone of Upper Silurian age, 

 89, 90. 



New York Mine, quartzite of, 59. 



