496 



INDEX. 



Page. 



Feldspar of muscovite-biotite-gneiss, plate of 298 



of peridotite 252,257,260,261 



of phyllite 440 



of pyroclastics 146, 147 



of quartz-mica-diorite-porpbyry, plate of 310 



cf rhyolite-porphyry 81,82,84,85 



pressure-etiects, plate of. 278 



of sedimentary inclusions in. granite 107 



of slate, altered 205 



of spi losite 200 



of tuff 145 



of ultrabaaic rocks 255 



of variolite Ill 



F volcanic conglomerate 144, 145 



of volcanic sand, plate of , 296 



orientation of 84,90,171 



outlined by apatite 239 



penetrated by biotite 414 



by tourmaline 57 



penetrating hornblende, plate of 322 



perthitic 41^2 



pressure effects in 42, 90, 92, 169, 254, 388, 464 



plate of 276 



replaced by biotite 193 



replaced by calcite 131 



twinning of 41, 42, 89, 191, 201, 224, 233, 468 



zonal intergrowtb "with hornblende 256 



plate of 322 



zonal intergrowtb with pyroxene, plate of 322 



zonal structure in 197, 233 



Fence River described 31,35,334,335 



referred to xix, 38, 39, 50, 51, 152, 329, 333, 408, 427, 430 



Fence Kiver area described 427-450 



Ferruginous chert 168 



of Mansfield formation described 62 



relations to clay slate 63 



Finlay, J. R., referred to 22 



Flag ore of Groveland formation 417 



Floodwood road 88 



Florence, iron ores at ^^"^'1 



discovery of ore deposits at 175 



Flow structure in aporbyolite-porphy ry 87 



plate of - 278 



in granite 45 



in hornblende-gabbro 244 



in metabasalt 99, 102, 105 



plate of 280 



in tufis 138 



{See Banding.) 

 Folding determined by magnetic observations, de- 

 scribed 306-372 



of Algonkian xxiir, 163, 427,428 



of Sturgeon Kiver 471,472.474 



of Archean xxiii 



of Crystal Falls district 26 



of graywacke, caused by intrusion 195 



of Groveland formation 448 



of Hemlock formation' 441 



of Mansfield formation ■ 438, 439 



of Marquette district 26, 452 



of Menominee district 26 



of Eandville dolomite 432-434 



of Sturgeon quartzite ., 399-400 



of Sturgeon River series 471, 472, 474 



of Upper Huronian described 158-162 



sketch of 179 



Folding of Upper Huronian, relations to intrusives. 189-190 



time of 161, 188 



Foliation of ampbibole 395 



of gneiss 430 



of granite 387 



of Sturgeon formation 402 



Forbes, indebtedness to 331 



Ford River, described 334.335 



Forsythe, R. J., analyses by 433 



Foster, J. W., and Whitney, J. D., on Felch Mountain 



range 375 



on Crystal Falls district le 



map of Lake Superior laud district 17 



referred to 21 



Fouque, F., on ellipsoidal basalt 120, 121, 124 



Fox, H., on ellipsoidal structure 118 



Frankenstein, wehrlite from 219 



Friction breccia of Hemlock formation 136 



Fumarolo action on sedimentaries 57 



Fundamental Complex. (See Arcbean.) 



Futterer, Karl, on pressure effects in quartz 90 



on pressure effects in feldspar 91 



G. 



Gabbro described 233-249 



altering to greenstone-schist 466 



crystallization of minerals of 262 



intruded by granite 194 



intruding hornblende-gabbro 265 



pressure effects in 247,248 



relations to peridotite 261 



Garnet of actinolite-schist 450 



of gray wacko 167 



of Mansfield schist 413 



of mica-schist 415 



pseudomorphs after chlorite 403 



Geikie, A., on ellipsoidal structure 114,118 



on Tertiary basalt 75 



Geographical limits of Crystal Falls district 25 



of Felch Mountain range 274 



Glass in metabasalt 99 



in tuff 138 



{See Devitrification.) 



Glauconite, alteration of 422 



of Groveland formation xx 



of Mesabi iron-bearing formation 422 



Glidden exploration 161, 163 



Globular basalt. {See Ellipsoidal structure in meta- 

 basalt.) 



Gneiss, analyses of 391 



developed by intrusion 198 



of Archean xviil 43 



described 390,391 



recrystallization of 390, 391 



Gneiasoid biotite-grauite described 43, 44 



Gneissoirf granite, included in granite-porphyry, 



sketch of 45 



of Sturgeon River ton gue described 463, 464 



pressure effects in 44 



Granite altering to clay slate 58 



altering to phyllite 58 



analyses of 389 



gradation into quartzite 51, 52 



banding of 45 



composition of 58 



contact "ffith dolerite 192 



