CONTENTS. VII 



Page. 



Traverse work .• ok 



Traverse plane table gg 



Measurements of altitudes iu connection with traverse work 89 



The aneroid oq 



i Organization of parties and distribution of work 91 



stadia measurements 92 



The Cistern barometer 94 



Use in field 95 



Reduction of barometric observations gg 



Utilization of the work of the public land surveys •_ 101 



Description of work 1 02 



Chapter V. 



Sketching 106 



Origin of topographic features 108 



Uplift 108 



Deposition from volcanic action HO 



Aqueous agencies HO 



Erosion HO 



Weathering HI 



Transportation and corrasion HI 



Profiles of streams and of the terrane 112 



Relations between stream and terrane corrasion 113 



Origin of canyons in plateau region 114 



Origin of detrital valleys 115 



Sinks 115 



Piracy 116 



.Origin of canyons in mountain ranges 116 



Origin of water and wind gaps " H6 



Junctions of streams 117 



Effect of structure on topographic forms 117 



Erosion of horizontal beds of rock 118 



Erosion of inclined beds of rock 120 



Age of topographic features 120 



Conception of base level 121 



Deposition from water 121 



River ridges 121 



Alluvial fans 122 



Terraces 122 



Glacial deposition 122 



Drumlins 123 



Pitted plains 123 



Osars 123 



Moraines 123 



Glacial erosion 123 



Amphitheaters 124 



Deposition from the atmosphere 12 1 



