76 GEOLOGICAL SURVEY OF THE TEREITOEIES. 



branches, the principal of which are Milk, White Earth, James, Vermil- 

 lion, and Big Sioux. The three last named rise in the far north and flow 

 through a much more rocky region and over a stony bed, and their waters, 

 as they pour them into the Missouri, contain far less sediment than any 

 of the others. Indeed, most of the rivers previously described flow through 

 a more or less barren country, with a thirsty atmosphere and a still more 

 Jthirsty soil, and on their way to the Missouri thej' lose nearly or quite 

 all their waters. Many of these long rivers, as Grand, Cannon Ball, Chey- 

 enne, in the autumn frequently become so drj- as to cease to be running 

 streams, while perhaps 100 miles above their mouth, if in the vicinity of 

 some mountains, there is a full supply of water. The Muscleshell Eiver 

 is a fine example. Toward the source of this river it is a fine running 

 stream ,• in the dry season it is lost almost entirely before reaching the 

 3Iissouri. Much more might be said in this connection, but enough has 

 been written to enable the reader to comprehend to some extent the vast 

 geographical area drained by the Missouri Eiver and its tributaries. 



F. V. HAYDEN, 

 V Uiiited States Geologist. 



Hon. J. S. Wilson, 



Commissioner of the General Land- Office. 



Geological Explorations in Wyoming Territory. 



Fort Steele, Union Pacific Eailroad, 



September 5, 1868. 



Sir : I have the honor to forward this day the first part of my prelim- 

 inary report from the field. Another portion, describing my examinations 

 from Fort Sanders to Benton Station and westward, will follow soon. 

 In the reports I have endeavored to give all the important details, and 

 as they are descriptive of regions almost or quite unknown previously to 

 the geologist, I hope they will be found of interest to you. The coal and 

 iron mines are of the highest value and almost unlimited in extent, while 

 indications of the precious metals have been observed in numerous locali- 

 ties. It is my intention to push on to Fort Bridger by way of the over- 

 land stage-route, and returning along the Union Pacific Railroad, so as to 

 construct a geological section of the route, making use of the cuts in the 

 road to give me a clearer knowledge of the different beds. It is my pur- 

 pose to take as full and accurate notes of the country along the road as 

 possible so that they can be used as a guide to travelers when they wish 

 to study the geology of the route. 



My party consists of nine persons. We have a two-horse ambulance 

 and a four-mule covered wagon, three tents, and four riding-animals. I 

 hope to return to Fort Sanders with all my party between the 1st and 

 10th of October. Ko draft has been received up to this time. All are 

 well and in good spirits. 



Very resi)ectfully, your obedient servant, 



F. V. HAYDEN, 



United States Geologist. 



Hon. Joseph S. Wilson, 



Commissioner General Land- Office. 



