INDEX.

Abajo Mountains, 67, 69, 152

Agricultural lands, 152

Alluvial cones and alluviation, 133, 139

Alpine sculpture, 36, 38

Altitudes of peaks and passes, 3, 117

Analogues of the laccolite, 98

Ancient rivers no larger than modern, 133

Antecedent drainage, 143

Arch, Bowl Creek, 45 , Crescent, 44 , Dana, 43 , G, 43 , Maze, 44 , Pulpit, 33, 147

Arches, Forces which produced laccolitic, 87

Aridity favorable to geological examination, 2, 98 of the Colorado Basin in former times, 120

Aubrey Sandstone, 8

Bad-lands, Sculpture of, 120, 140

Bischof, on contraction of igneous rocks in cooling, 76

Blue Gate flexure, 13 Sandstone, 4 Shale, 4

Bonneville, Outlet of Lake, 134

Bowl Creek arch, 45

Cañons of the Colorado as obstructions to travel, 1, 151 as evidence of arid climate, 120

Carboniferous strata, 8

Carriso Mountains, 69, 152

Circle Cliffs, 14

Cleavage, Slaty, not found, 66 , Vertical, produced by sapping, 55

Cliffs, Circle, 14

Climate, Arid, favorable to geological examination, 2, 98 , General influence of, on erosion, 103 , Influence of, on sculpture, 117

Coal, 5, 151

Colorado Basin, History of the, 84 Desert, 134 River, Origin of the, 85

Colors of sandstones, Local variation of, 7

Comminution of detritus aids transportation, 106

Competence, 110

Conditions of rock flexure, 83

Cones, Alluvial, 133

Consequent drainage, 143

Contact phenomena, 65

Contraction of igneous rocks by cooling, 75, 80

154Corrasion, 100, 101 , Relation of, to declivity, 112 , to friction of flow, 109 , to transportation, 111

Cover of the laccolites, Depth of the, 86, 94

Crescent arch, 44

Cotta, Prof. Bernhard von, cited, 75

Cretaceous period, Disturbance at the close of the, 10, 85 rock series, 4

Cross-lamination, Inclination of, 7

Dana arch, 43

Declivity, General influence of, upon erosion, 102 of stream beds, relation to corrasion, 112 , relation to transportation, 108 , Relation of, to quantity of water, 113

Declivities, Influence of unequal, on divides, 140

Degradation (see Erosion), 99, 115

Delesse on contraction of igneous rocks in cooling, 76

Densities of igneous rocks, 75 of sedimentary rocks, 77

Density a condition of laccolitic intrusion, 73, 74 of porphyritic trachyte, 77

Denudation (see Erosion), 99, 115 of laccolites, 21

Deposition by running water, 111

Diameters of laccolites, 92

Dike near Mount Ellsworth, 59

Dikes and sheets defined, 20 , Flat-topped, 28 of Mount Ellsworth, 23 of Mount Holmes, 28 , Relation of, to strains, 96

Dinah Creek Pass, 3

Dirty Devil River, Flood-plains of, 131

Distances, Table of, 17

Distribution of laccolites, Horizontal, 20, 30 , Vertical, 21, 56

Divides in bad-lands, Rounding of, 122 , Instability of, 139 , Law of, 116 , Stability of, 138

Drainage lines, Instability of, 125 , Stability of, 124 , Systems of, 124, 143

Dutton, Capt. C. E., on the intrusive rocks, 61

Economic geology, 151

Elk Mountains, 69

Ellen Mount (see Mount Ellen).

Ellsworth Mount (see Mount Ellsworth).

Energy of muddy streams, 108 streams, how measured, 106

Equal action, Principle of, 123

Erosion, Conditions which control, 102 , Influence of climate upon, 103 , Influence of declivity upon, 102

155Erosion, Influence of rock texture upon, 103 , Influence of vegetation upon, 104 of Mount Ellsworth, 25 , Principles of, 99 , Processes of, 99

Farming lands, 152

Faults on Mount Ellsworth, 23 Mount Holmes, 28 , Region of, 12, 15

Fish Lake Valley, Structure of, 14

Fissure veins limited in depth, 82 not found in the Henry Mountains, 83, 151

Flaming Gorge Group, 6

Flat-topped dikes, 28

Flexure of rocks, Conditions of, 83

Flood-plain defined, 127

Flow of streams, Friction of, 107, 109

Folds, The Great, 10, 11, 85

Forces which produce laccolitic arches, 87

Form of laccolites, 55

Frost, 104

Friction of flow of streams, 107, 109

Geikie laccolite, 41

Gold and silver, 151

Granite, Eruptive, 70

Graves, Mr. Walter H., 1

Gray Cliff Group, 6

Grazing lands, 152

Heights, 3, 117

Henry, Prof. Joseph, 1

Henry Mountains, Altitudes of the, 2, 117 caused by resistance of trachyte to erosion, 25, 35 , Contributions of the, to the principles of erosion, 99 , Detailed description of the, 22 , Drainage of the, 144 , Economic value of the, 152 , Planation in the, 127, 149 , Relation of vegetation to type of sculpture in the, 118 , Route of travel to the, 14; their structure laccolitic, 19, 53

Henry’s Fork Group, 4

Hillers, Mount (see Mount Hillers).

Hills of planation, 130

Historical note, 66

History of the Colorado Basin, 84

Holmes, Mount (see Mount Holmes).

Holmes, Mr. W. H., on the Elk Mountains, 70 La Lata and Carriso Mountains, 69

Hopkins on the power of currents, 106

Howell laccolite, 34 , Mr. Edwin E., Fossils discovered by, 5; observation of the Henry Mountains, 66; observation of the Navajo Mountain, 69

Hydrostatic equilibrium, Law of, 72

Igneous mountains of the Plateau Province, 67

156Igneous rocks, Contraction of, by cooling, 75, 80

Inconsequent drainage, 143

Instability of divides, 139 drainage lines, 125

Interdependence of drainage slopes, 123, 141

Internal structure of laccolites, 55

Intrusive rocks of the Henry Mountains, 59, 61

Isolation of the Henry Mountains, 2, 18

Jerry Butte, 34

Jukes Butte, 46

Jukes, Prof. J. Beete, on prismatic structure, 76

Jura-Trias rock series, 5

Kaibab structure, 11

Laccolite A, 32 B, 32 C, 32 D, 35 E, 41 F, 42 , Geikie, 41 H, 46 , Hillers, 30 , History of the, 95 , Howell, 34 , Jukes, 46 , Marvine, 42 , Newberry, 41 of Mount Ellsworth, 27 of Mount Pennell, 36 of the western base of Mount Ellen, 40 , Peale, 47 , Possible analogues of the, 98 , Scrope, 47 , Sentinel, 38 , Shoulder, 42 , Steward, 32 , The, defined, 19

Laccolites, Age of the, discussed, 84 , Composite, 55 , Denudation of, 21 , Depth of cover of, 86, 94 , Detailed description of, 22 , Diameters of, 92 , Form of, 55, 91 , Holmes, 27 , Horizontal, distribution of, 20 intruded in soft beds, 58 , Limital area of, 90, 97 thickness of, 91 , Material of, 59 not prismatic, 55 of the Elk Mountains, 70 of other regions, 97; size limited, 86 subsequent to the strata which inclose them, 51 157, Vertical distribution of, 21, 56, 65

Laccolitic mountains of the Plateau Province, 67, 69 structure characteristic of the Henry Mountains, 19, 53 Sierra La Sal, etc., 69 conditioned by densities, 74 correlated with acidic lavas, 71 , Discussion of the origin of, 72

Lake Bonneville, Outlet of, 134 , Great Salt, Outlet of, 134 Winipeg, Origin of, 126

Land, Agricultural, 152 , Grazing, 152 sculpture, Principles of, 99, 115 , Timber, 152

La Lata Mountains, 68, 69, 152

La Sal Mountains, 68, 69, 152

Law of divides, 116 , Exception to the, 122

Lewis Creek plain, 128

Limital area of laccolites, 90, 97 thickness of laccolites, 91

Load, Relation of, to comminution, 107

Mallet, Robert, C. E., on contraction of igneous rocks in cooling, 76

Marvine laccolite, 42

Ma-suk’ Plateau, 13 Sandstone, 4 Shale, 4

Maze arch, 44

Metamorphism in the Henry Mountains, 65 on Mount Ellen, 38 Ellsworth, 24 Hillers, 31 Holmes, 28

Minerals of the Henry Mountains, 61, 64

Monoclinal shifting, 135, 140

Mount Ellen, Character of sculpture of, 118 , Drainage of, 148 , Structure of, 38 , Topography of, 3 , Vegetation of, 118 Ellsworth, Character of sculpture of, 25, 118 , Drainage of, 145 , Stereogram of, 23, 95 , Structure of, 22 , Topography of, 3 , Vegetation of, 118 Hillers, Character of sculpture of, 119 , Drainage of, 147 , Structure of, 30 , Topography of, 3 , Vegetation of, 118 Holmes, Character of sculpture of, 118 , Drainage of, 146 , Structure of, 27 , Topography of, 3

158Mount Holmes, Vegetation of, 118 Pennell, Character of sculpture of, 119 , Drainage of, 148 , Structure of, 35 , Topography of, 3 , Vegetation of, 118

Mount Taylor, 71

Mud-cracks, Fossil, 9

Navajo Mountain, 69, 152

Newberry, Dr. J. S., on the Sierra Abajo, 67 La Sal, 68 laccolite, 41

Oblique lamination, Inclination of, 7

Peale, Dr. A. C., on igneous mountains of Colorado, 69 on the Elk Mountains, 70

Peale laccolite, 47

Pennell, Mount (see Mount Pennell).

Pennellen Pass, 3

Pine Alcove Creek, Former course of, 130

Planation, 126, 139 , Hills of, 130

Plasticity of solids, 82, 83, 97

Plateaus enumerated, 13

Precipitation from running water, 111

Pressure a condition for rock flexure, 81, 83, 96

Prismatic structure, Absence of, 55, 76 defined, 55

Ponding, 125, 139

Porphyritic trachyte, 60, 64

Porphyry; use of term discussed, 63

Powell, Prof. J. W., on the climate of the Colorado Basin, 120

Pulpit arch, 33, 147

Rankine on flexure of beams, 90

Red Gate flexure, 13 , Flood-plains of, 131 , The, 16

Revet-crags defined, 25 of Mount Hillers, 31 of Mount Holmes, 29 of Mount Pennell, 37

Ripple-marks, Fossil, 16

River terraces produced by planation, 132

Rivers, Ancient, no greater than modern, 133

Rock texture, Influence of, on sculpture, 115, 135, 140 , General influence of, on erosion, 103

Rocks of the Henry Mountains, Intrusive, 59, 61 , Sedimentary, 3

Rotation of the earth, 142

Route to the Henry Mountains, 14

San Rafael fold, 16, 18

Scrope laccolite, 47

Sculpture, Alpine, 36, 38 influenced by climate, 117 distribution of divides, 116 rock structure, 115, 135, 140

159Sculpture of bad-lands, 120 of Mount Ellsworth, 25 , Principles of, 99, 115

Sentinel Butte, 38

Sheets and dikes defined, 20 of Mount Ellsworth, 24 of Mount Holmes, 28 , Relation of, to strains, 96

Shin-ar’-ump Group, 6

Shoulder laccolite, 42

Sierra Abajo, 67, 69, 152 Carriso, 79, 152 La Lata, 68, 69, 152 La Sal, 68, 69, 152

Solidity of rocks not absolute, 82, 83, 97

Specific gravities (see Densities).

Specimens of Henry Mountain trachyte, 60

Springs; relation to soft strata explained, 82

Stability of divides, 138 of drainage lines, 124

Stereogram, how made, 11, 49 of Mount Ellsworth, 23, 95 of the Henry Mountains, 49 and Waterpocket flexure, 11

Steward laccolite, 32 , Mr. John F., cited, 66

Strains shown by dikes and sheets, 96

Stretching of strata, 80

Structure, Law of, 115

Suncracks, Fossil, 9

Superimposed drainage, 144

Systems of drainage, 124, 143

Table of altitudes, 117 densities of sedimentary rocks, 78 in order of superposition, 79 trachytes, 77 diameters of laccolites, 92 distances, 17 mean densities of certain rock series, 80

Tantalus Creek, 17 , Flood-plains of, 131

Taylor, Mount, 71

Temple Creek, 16 , Flood-plains of, 131

Terraces, River, produced by planation, 132

Tertiary strata protected by lava, 12

Thicknesses of individual strata, 7

Thompson, Prof. A. H., 1, 66

Thousand Lake Mountain, View from, 15

Timber land, 152

Trachyte, Porphyritic, 60, 64

Trachytes of the Henry Mountains not vesicular, 51, 64

Transportation, 100, 101 by streams, analyzed, 106 Conditions which determine rate of, 110 160favored by comminution of material, 106 declivity, 108 quantity of water, 109 , Relation of, to corrasion, 111

Trend, Absence of, 2, 30, 98

Tu-nunk’ Sandstone, 4 Shale, 4

Unconformities, 8, 85

Unconformity at Salina, 14

Vegetation, General influence of, on erosion, 104

Veins, Absence of fissure, 83, 151 , Fissure, limited in depth, 82

Vermilion Cliff Group, 6

Vertical cleavage by sapping, 55

Volcanoes of the Plateau Province, Extinct, 67, 70

Volume of streams, Influence of, on erosion, 104 transportation, 109 , Relation of, to declivity, 113

Warren, General G. K., on the valley of the Minnesota River, 126

Waterpocket Cañon, 137 flexure, described, 12 , Passes across the, 16

Watersheds (see Divides).

Weathering, 100

White, Dr. C. A.; identification of Henry’s Fork Group, 4

Whitney, Prof J. D., on inclination of bedding, 52

Winipeg, Origin of Lake, 126

Zones of laccolites, 57, 58, 74

TRANSCRIBER’S NOTES

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30 degradation, less than one-half has been stripped of its cover of arch-arching degradation, less than one-half has been stripped of its cover of overarching

Typos fixed; non-standard spelling and dialect retained.

Used numbers for footnotes.