X CONTENTS. 



Economics — continued. 



Copper 196 



Iron 197 



Gypsum 19*7 



A PRELIMINARY REPORT ON THE COAL FIELDS OF THE COLORADO RIVER, BY RALPH S. TARR. 



Introduction 201 



Sub-Carboniferous 202 



Carboniferous 203 



Richland sandstone 204 



Milburn division 205 



Brownwood division ... . 206 



"Waldrip division - 20^ 



Coleman division 210 



Economics — 



Coal 212 



Iron 215 



Manganese 216 



Oil, Gas, and Salt Water 216 



GEOLOGY OF TRANS-PECOS TEXAS — PRELIMINARY STATEMENT — BY W. VON STREERUWITZ. 



Character of country 219 



Sierra Blanca Mountain 219 



Quitman Mountain 220 



Carrizo Mountain 221 



Sierra Diabokr 222 



Mineral resources 223 



Agriculture and irrigation .... 226 



Development 228 



Conclusions . 231 



Topographical notes 232 



A PRELIMINARY REPORT ON THE CENTRAL MINERAL REGION OF TEXAS, BY THEO. B. COMSTOCK. 



Introduction 239 



Part I — Stratigraphic Geology 254 



Archsean group ...... ... ... 255 



Burnetan system. 255 



Age of igneous irruptions 263 



Irruptions of Burnetan system . , 267 



Eernandan system 267 



Taxonomy of the system. 274 



Irruptives of the system 275 



Eparchsean group 276 



The Texan system 276 



Taxonomy of the system 280 



Classification of Pre-Paleozoic igneous rocks 281 



Paleozoic group 283 



The Cambrian system . 283 



Hickory series . . 285 



The Riley series . . ; 286 



The Katemcy series 289 



Taxonomy of the system 292 



Irruptives of the Cambrian period 292 



The Silurian system , . . . . , 293 



The Leon series « 295 



The San Saba series 301 



Taxonomy of the system 305 



Irruptives during and succeeding the Silurian period 307 



The Niagara (Upper Silurian) system 309 



The Devonian system 310 



The Post- Paleozoic uplifts 311 



The Pre-Cretaceous movement 312 



Irruptions accompanying the east-west uplift 314 



