AMERICAN GEOLOGY DECADE OF 1870-1819. 589 



nearly opposite the mouth of Solomons Fork. Thence the route \ay 

 down the south side of Smoky Hill and Kansas rivers to Lawrence, 

 and thence across the Kansas in a northeastward direction to Leaven- 

 worth city. The explorations were very successful, and the results 

 embodied in numerous papers in the Proceedings of the Academy of 

 Natural Sciences of Philadelphia and elsewhere. 



In April, 1859, Capt. W. F. Raynolds was instructed to organize an 



expedition for the exploration of the country from which flow the 



upper tributaries of .the Yellowstone River and of the mountains in 



which these tributaries and the Gallatin and Madison 



Hayden with , . _^ 



Raynoids's forks ot the Missouri have their source. On April 22 



Expedition, 1859. . r 



Doctor Hayden was appointed surgeon and naturalist 

 of this expedition. The party left St. Louis May 28, 1859, going - up 

 the Missouri to Fort Pierre, which point was reached about the middle 

 of June. From here the route was westward and northwestward to 

 the Yellowstone River by way of the Cheyenne, the Belle Fourche, 

 and Powder rivers. The Yellowstone was reached near the mouth of 

 the Big Horn about the middle of August. From the Yellowstone 

 the expedition turned southward early in September and followed 

 up the Big Horn, skirting the eastern edge of the Big Horn Moun- 

 tains, finally going into winter quarters on Deep Creek, near the North 

 Platte River, about the middle of October. 



The following May (1860) explorations were resumed, the expedi- 

 tion going to Fort Benton, on the Missouri, by way of the North 

 Platte. Wind, Snake, and Madison rivers. Fort Benton was reached 

 July 11. On the 23d of July the return trip to Omaha was begun, 

 the party proceeding by boat down the Missouri River to Fort Union, 

 and from the latter point by land. Omaha was reached October 1, 

 where the party disbanded. 



The report of this last expedition, published early in 1869, com- 

 prised some 171 octavo pages, including 30 pages of paleontological 

 notes by J. S. Newberry. It was accompanied by a colored geological 

 map of the region north of the forty-second parallel and lying between 

 the ninety-eighth and one hundred and fourteenth meridians (tig. 97). 



Some of the more important conclusions arrived at by Hayden as a 

 result of observations on these expeditions are as follows: He announced 

 in 1857 the discovery of Potsdam sandstone in the country about the 

 headwaters of the Yellowstone, and in a preliminary 

 laHy n wTk Hayden ' s publication in the American Journal of Science for 

 L861 described it as more or less changed by heat from 

 beneath. The other formations noted were Carboniferous (including 

 Permian?), red arenaceous deposits overlaying -the Carboniferous, but of 

 uncertain age; Jurassic, Cretaceous, and Tertiary deposits. During 

 the long interval that elapsed between the deposition of the earliest 

 part of the Silurian and the commencement of the Carboniferous, 



