TABLE OF CONTENTS 



Page 



Chapter I. Gilbert's ancestry and youth 1 



Foreword 1 



The Gilbert family 2 



Boyhood in Rochester 2 



Four years at college 5 



A brief experience in school-teaching 5 



Apprenticeship in Cosmos Hall 6 



The Cohoes mastodon 6 



The Mohawk gorge at Cohoes 8 



Half a century of diaries 8 



Preparation of this memoir 9 



Chapter II. Two years on the Ohio survey 11 



First experience in field geology 11 



Surface geology of the Maumee Valley 12 



Chapter III. Three years on the Wheeler survey. 15 



Three seasons in the West 15 



Field notebooks: Personal experiences 16 



Notes on scientific topics 19 



A boat trip into the Colorado Canyon 21 



Chapter IV. Geology in the Wheeler reports.- 25 

 Reports on the Great Basin and plateau 



provinces 25 



Geological generalizations and conclusions. 26 



Stratigraphy 28 



Historical geology 28 



The great unconformity 29 



Submergence of the Archean continent 30 



Volcanic rocks and structures 31 



Diastrophism: Fractures and flexures 32 



Upheaval of the Zufii dome 33 



The upheaval of mountains 34 



Hot springs and diastrophism 35 



The Colorado plateau as a field for geo- 

 logical study 35 



Chapter V. Physiography in the Wheeler reports. 37 



The gradual growth of physiography 37 



Processes and products of stream erosion . . 39 



Normal hanging valleys 40 



Cataracts and rapids 40 



Graded rivers 41 



Cliffs and slopes in canyon walls 41 



Retreating escarpments ■ 42 



Topography of fractures and flexures 43 



Volcanic features 45 



Various minor topics 46 



Subsequent valleys 47 



Planation by subaerial erosion 48 



Two laws of erosion 49 



Examples of subaerial degradation 50 



Successive periods of erosion 51 



The Gila conglomerate 52 



Summary 52 



Page 

 Chapter VI. The basin ranges in the Wheeler 



reports 53 



The problem of the basin ranges 53 



Physiographic principles 53 



Three-fold treatment of surface forms 54 



Age and structure of the ranges: First 



Wheeler report 55 



Bearing of range form on range origin 56 



The basin ranges as upheaved and warped 



fault blocks 57 



Upheavals and eruptions 59 



Erosion of the upheaved ranges 59 



Basin ranges in the second Wheeler report. 60 

 Physiography and geology in the basin- 

 range theory 61 



Views of Powell and Dutton 62 



Gilbert on the origin of the Sierra Nevada. 63 

 Incomplete statement of the basin-range 



theory 63 



Chapter VII. First winters in Washington 67 



Extension of scientific acquaintance 67 



Marriage and home making 69 



Chapter VIII. Five years on Powell's survey. 71 



Acquaintance with Powell 71 



Field work for the Powell survey 72 



Two visits to the Henry Mountains 74 



The Henry Mountains report 75 



Observed and inferred structures 78 



Recognition of laccoliths 79 



The base of the laccoliths 81 



Chapter IX. The conditions and processes of 



laccolithic intrusion 83 



The Henry Mountains as typical laccoliths. 83 



The hydrostatic law and rock cohesion 84 



Mechanics of laccolithic intrusion 85 



Relation of diameter and depth 86 



Genetic definition of a laccolith 87 



Gilbert's theory not generally understood. 88 



Dana's alternative theory 90 



Effect of magmatic viscosity 91 



Evidence for magmatic fluidity 92 



Validity of Gilbert's view 92 



Chapter X. The principles of land sculpture 95 



A physiographic classic 95 



Land sculpture and climate 97 



Wandering streams on planation surfaces. . 98 



Interdependence of drainage lines 99 



Terminology of drainage lines 99 



The Waterpocket Canyon 100 



Subsequent valleys in the Henry Mountains. 102 

 The subsequent origin of Waterpocket 



Canyon 103 



Baselevel and time 104 



Progress in physiography 106 



in 



