X CONTENTS. 



CARBONIFEROUS CEPHALOPODS, BY ALPHETJS HYATT. 



Introduction 339 



Nautiloidea 339 



Goniatitinae 354 



REPORT ON THE GEOLOGY OF NORTHWESTERN TEXAS, BY W. F. CUMMINS. 



Introduction 359 



Part I. Stratigraphic geology 359 



Silurian 360 



Devonian 360 



Sub-Carboniferous 360 



Carboniferous 36*7 



Permian 394 



Triassic 424 



Tertiary 431 



Part II. Economic geology — 



Coal 436 



Natural gas 441 



Salt 444 



Copper ore 449 



Iron ore 455 



Gypsum 455 



Building stones 459 



Building materials 461 



Agriculture 469 



Archaeology 489 



Part III. Description of counties 492 



Young County — 



Coal .• 493 



Topography and drainage 502 



Geology 502 



Soils, timber, and water. 503 



Building material 504 



Iron ore 504 



Salt 605 



Montague County — 



Topography and drainage 506 



Geology 506 



Soil 506 



Timber, water, and building material 507 



Coal 508 



Copper and galena , : 509 



Jack County — 



Drainage and topography 509 



Geology 509 



Soil, timber, and water , 510 



Building material 511 



Coal 511 



Wise County — 



Topography and drainage 516 



Geology and soil 516 



