CONTENTS. 



Page. 



Introduction 7 



The Edwards Plateau as a source of water supply 8 



Description of the region 8 



Structure of the Edwards Plateau as a catchment area 9 



Structure of the Edwards Plateau as to influencing the behavior of the 



precipitated water 10 



Climatic conditions of the region ^ 10 



Rainfall 10 



Atmospheric moisture 11 



Water supply of the Edwards Plateau 11 



Rivers 12 



Springs L3 



Gravity springs 13 



Fissure springs 13 



The vegetation of the Edwards Plateau 14 



General description 14 



Transformation of prairie into timberland 14 



The species of trees and their geographic affinities 15 



Distribution and character of the forest 16 



Timber of the canyons and stream ways 16 



The hill and bluff timber 16 



Mixed timber 16 



Shinneries 17 



Mountain oak thickets 18 



Cedar brakes 18 



The post oak timber 19 



Commercial value of the hill timber 20 



Agencies which tend to reduce the timbered area 20 



Clearing for farm lands 20 



The demand for fuel, posts, ties, and other classes of timber 21 



Cedar brake tires 21 



Encroachment of timber growth upon the Edwards Plateau 22 



Energy and rapidity with which lands are reforested 22 



How scrub oak timber gains on the upland prairies and divides : 23 



How cedar captures adobe slopes 23 



The spread of mesquite and chaparral 23 



How the timber gets started on steep, rocky hillsides 24 



Influence of the Edwards Plateau upon climate, soil, and water supply 24 



Influence of the timber growth upon climate 24 



Influence upon temperature 25 



Influence upon soil and water supply 26 



Illustrations of the effects of the Edwards Plateau forest 27 



The problem of maintaining a forest cover on the hilly country of the Edwards 



Plateau 29 



5 



