CONTENTS 



Page. 



JjETTER TO THE SeCRETAKY 1 



GEOLOGY, MINERALOGY, AND MINING INDUSTRY. 



Eeport of F. V. Haydex, United States geologist 19 



Chapter I. Brief history of the Lignitio group, first studied on the Upper 

 Missouri — early views entertained by Meek, Newberry, and other paleon- 

 tologists on the age of this group — the Lignitio group of the North- 

 ■west believed to be continuous southward with the Colorado and Lara- 

 mie beds 19 



Chapter II. The Lignitic group as examined at Canon City — Colorado 

 Springs — northward to Cache a la Poudre Creek — Monument Creek 



group — probable age of these groups 28 



Appendix to Chapter II, by H. T. West 38 



Chapter III. Resume of the geology along the eastern base of the Front or 

 Colorado range : Silurian, Carboniferous, Triassic, Jurassic, and Creta- 

 ceous groups 40 



The Carboniferous group - 42 



The Red beds or Triassic group 42 



The Jurassic 44 



The Cretaceous 45 



Chapter IV. Ancient lake-basins — Glacial lakes — Morainal deposits in the 

 vaUey of the Upper Arkansas River and along both flanks of the Sa- 



watch Mountains 47 



Chapter V. General view of the geography and geology of the Elk Mount- 

 ains — eruptive granites — rhyolites and dikes — erosion on a grand scale — 



local drift-deposits 54 



Chapter VI. Report on the Geology of the Northwestern portion of the Elk 



range, by W. H. Holmes 59 



Letter to Dr. Haydeu 59 



The Roaring Fork synclinal 59 



Geology of Sopris Peak and vicinity 61 



Geology of the district drained by Rock Creek 63 



The great fault-fold of the Elk range.: 68 



Report of A. C. Peale, M. D., geologist of middle division 73 



Letter to Dr. F. V. Hayden 75 



Introduction , 77 



Chapter I. Surface geology — valley of Eagle River 79 



Chapter II. Surface geology — Grand River and its tributaries 85 



Chapter III. Surface geology — Gunnison River and its tributaries 94 



Chapter IV. Archaean areas of Eagle, Grand, and Gunnison Rivers 106 



Chapter V. Stratigraphy — Paleozoic formations 110 



Silurian age 110 



Primordial period — Potsdam group 110 



Canadian period — Calciferous and Quebec groups Ill 



Remainder of Silurian 113 



Devonian age 114 



Carboniferous age 114 



Permian or Permo-Carboniferous 117 



Chapter VI. Stratigraphy — Mesozoic formations 121 



Triassic 121 



Jurassic 124 



Cretaceous 128 



Lower Cretaceous— Dakota group (No. 1) 128 



Middle Cretaceous (No. 2 and No. 3) 135 



Middle Cretaceous (No. 4) 137 



Upper Cretaceous 137 



in 



