INDEX. 
A. Page. 
Acknowledgments to those aiding 13 
Alabama hematite, comparison of, with 
Iron Springs ores 73, 95 
Albite, precipitation of 8 
Alluvial fans, description of 18, 22, 45 
Amphibole, development of 16 
Andesite, analyses of 58-59, 81 
composition of, plates showing 48, 50 
variations in 59, 61 
density of 47 
dike of 46 
distribution of 46 
erosion of, view of 22 
fissures in, iron ores in 7, 67, 86 
figures showing 71, 74 
origin of. See Fissures. 
See also Laccoliths. 
Andesite-limestone contact. See Limestone- 
andesite contact. 
Antelope Springs, rocks near 18 
Anthracite beds, age of 64 
Apatite, alteration of 9, 83 
Aubrey limestone, correlation of 63 
Aviculopecten, occurrence of 37, 63 
B. 
Beck, Richard, on ore deposition 94 
Bibliography 97 
Biotite dacite, analysis of 58 
description of 55-56 
Biotite-hornblende-pyroxene andesite, de- 
scription of 56-57 
Blackwelder, Eliot, fossils determined by.. 37,63 
Blowout contact deposit, section of, figure 
showing 69 
view of 68 
Breccias, cements of 70 
iron ores in 7, 69-70 
occurrence and description of 39 
British Colombia, iron ores in 92 
Bull Valley district, iron ores of 91-92 
iron ores of, comparison of Iron Springs 
ores and 91-92 
map showing 90 
C. 
Calcite, redeposition of 9, 82 
iron ores in 92 
Carboniferous rocks, correlation of 63-65 
occurrence and description of 16, 24-37 
relation of, to Cretaceous rocks 16-17 
See also Homestake limestone. 
Cedar Canyon, location and character of. . . 15 
rocks in 1. 1 
Page. 
Chalcedony, analysis of 81 
introduction of 80-81 
Chesapeake claim, Assure vein on, view of. 68 
map of Pocket. 
Claron limestone, age of 64 
character of 42 
conglomerate in 42 
dip of 43 
distribution of 41 
fossils in 43 
metamorphism of 43-44 
mineralization of 44 
structural relations of 41 
thickness of 41 
Clay, occurrence and description of 45 
Clinton ores, comparison of Iron Springs 
ores and 73, 95 
Colorado, iron ores in 92 
Concentration, secondary, causes of 9 
description of 75-82 
extent of 9 
Conglomerate, occurrence and description 
of 39-40, 42, 44 
Correlation, discussion of 62-65 
Cretaceous rocks, character and distribu- 
tion of 16, 37-41 
correlation of 64-65 
relation of, to Carboniferous rocks 16-17 
See also Pinto sandstone. 
D. 
Density, alteration in 8, 34-35 
Desert Mound, development at 74 
mining claims at, map showing 66 
ore deposits at, map of Pocket. 
section of, figure showing 68 
view of 70 
Dickman, R. W., aid of 13, 71 
Drainage, character of 14. 22 
relation of, to faults 22 
Duluth group, map of Pocket. 
Dutton, C. E., on Iron Springs region sedi- 
ments 62-63 
E. 
Edmondia, occurrence of 37 
Elevation, range of 14 
Eocene series, character and occurrence 
Of 17-18.22, 11-11 
See also Claron limestone. 
Erosion, development by 7, 21, 22, 23, 86 
Escalante Desert, deposits in 45 
Excelsior claim , map of Pockel 
Exploration, extent of 7 
hints for 86 89 
99 
