' REVIEW OF RESULTS OF INVESTIGATIONS 289 



the age of the quartzite series and of the Paleozoic beds which overlie 

 them. 



State of geological Knowledge 



The only systematic exploration of the entire range was made by the 

 Fortieth Parallel party under my charge, in the summers of 1869 and 

 1871. In the same years Powell made his famous explorations of the 

 canyons of the Colorado, and in so doing traversed the eastern end of 

 the range in his boat journeys down the meandering canyons of the 

 Green river. 



In the summer of 1871 Hay den made a hasty reconnaissance along 

 the northern slopes of the range, penetrating the central core at a single 

 point near the head of Blacks fork, where he found Carboniferous fossils 

 in the flanking limestones and "suspected" that the underlying quartzites 

 might be Silurian from their resemblance to the Potsdam sandstones. 

 During the seasons of 1874 and 1875 Powell headed parties that studied 

 the geology of the eastern part of the range and the surrounding Cre- 

 taceous and Tertiary regions. From that time until 1903 there is no 

 record of any geological study of the range. 



At the time when the Fortieth Parallel field Avork was being carried 

 on, what was known of the geology of the Cordilleran region was mainly 

 derived from observations of geologists accompanying military expedi- 

 tions, generally as surgeons. It may be summed up as follows : 



On the Great plains, especially about the upper Missouri river, Meek 

 and Hayden had established the Cretaceous section and named its five 

 divisions, but were uncertain whether the upper coal-bearing member 

 might not more properly be classed as Tertiary. The beds beneath them 

 were recognized as Jurassic from their fossils, while the red sandstones 

 under these were judged from their position and lithological character- 

 istics to be probably Triassic. Unconformably over the whole lapped 

 various series of fresh-water Tertiary beds, whose age was not yet deter- 

 mined, though in the very summer in which the Uinta work was being 

 carried on the first vertebrate remains were being collected from the 

 Eocene beds of the adjoining Green Eiver basin. 



In California the auriferous slates had recently been determined to be 

 of Jurassic age, which was specially interesting as affording a decided 

 negative to Murchison's hitherto generally received dictum, that gold 

 only occurs in rocks as old as the Silurian. 



From the wide mountain region between the Sierra Nevada and the 

 Eocky mountains, popularly known as the Great American desert. Car- 

 boniferous fossils had been brought back by the various government 



