No. 2. 



REPORT 



UPON THE 



PROGRESS Of THE PACIFIC RAILROAD EXPLORATIONS AND SURVEYS. 



NOVEMBEB, 1855. 



BY CAPTAIN A. A. HnMPHRETS, CORPS OF TOPOGRAPmOAL ENCINKEBS. 



War Department, 

 Office Pacific Railroad Explorations and Surveys, 



Washington, November 29, 1855. 



Sir: Since my report to you of February 5, 1855^ the general map of the territories of the 

 United States lying between the Mississippi river and the Pacific ocean has been completed as 

 far as the materials collected admit, and is in the hands of the engraver. The labors of the 

 parties organized for continuing explorations will afford data for still further additions. 



Many of the maps, drawings, and scientific papers intended to form part of the reports 

 submitted to you by the first exploring parties, soon after their return from the field, could 

 only be prepared after an elaborate use of the materials collected. In some instances hastily 

 prepared drawings and preliminary reports were temporarily substituted for the more elaborate 

 results, which are now, for the most part, complete. 



The results of the investigations in the various branches of physical science in connexion 

 with the expeditions are of great practical value, and full of scientific interest. The geological 

 and meteorological reports are eminently so in many points of view. By the former it will be 

 perceived that the sources and quality of building materials at various remote and important 

 localities have been determined, and rich deposits of gypsum and limestone have been marked 

 out. On the routes of the 35th and the 32d parallels, the structure of desert areas has been 

 minutely studied with special reference to the practicability of obtaining water by wells or by 

 boring, and generally with the most satisfactory results. From the report of Mr. W. P. 

 Blake, the geologist of the expedition in charge of Lieutenant R. S. Williamson, it appears 

 that the structure of the Colorado desert, between Fort Yuma and the Coast mountains is very 

 favorable to the success of artesian borings, and it is considered probable tliat an abundant 

 supply of water would be obtained by boring to a moderate dei)th. Such a result would be 

 of extreme importance, not only by facilitating communication between Fort Yuma and the 

 coast for government trains, but as a relief to the emigrant parties which are constantly cross- 

 ing to California through New Mexico and Sonora. The general nature and composition of 

 the soils and sub-soils over the region explored has been determined, and analyses of the most 



