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 Mount 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 Sculpture 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