195

CONTENTS

• Page.
• Introduction 199
• Geography of the region ...201
  • Rio Grande Plain ...202
  • Balcones scarp line...203
  • Edwards Plateau ...204
• General principles of artesian waters ...212
  • Capacity of rooks-for absorbing moisture...213
• Geology of the region ...215
  • • Table of geologic formations of the region under discussion ...216
  • Paleozoic formations ...217
  • The Cretaceous ...217
    • Comanche series (Lower Cretaceous) ...218
      • The basement beds ...218
      • Travis Peak formation ...219
        • Gillespie formation ...221
      • Glen Rose formation ...221
      • Walnut formation ...226
      • Comanche Peak limestone ...226
      • Edwards limestone ...227
      • Fort Worth limestone ...235
      • Del Rio clays ...236
      • Shoal Creek limestone ...237
    • Gulf series (Upper Cretaceous) ...238
      • Eagle Ford shales ...239
      • Austin chalk ...239
      • Taylor formation ...240
        • Anacacho formation ...240
      • Webberville and Eagle Pass formations ...241
  • The Eocene ...243
  • Alluvial deposits of the Neocene, Pleistocene, and Recent epochs ...243
    • Uvalde formation ...244
    • Pleistocene terraces ...247
    • Terraces of the Colorado River ...247
      • The Asylum terrace ...249
      • The Capitol terrace ...249
      • The present flood plain ...250
      • Terraces on the south side of the Colorado River ...251
    • Terraces of the Rio Grande ...251
    • Onion Creek marl and allied deposits ...252
    • Terraces of the Nueces and Leona rivers, and the Leona formation ...253
    • The wash ...254
    • Fry-pan deposits ...255
    • Tepetate and "tierra blanca" ...256