148 DESCEIPTIVE GEOLOGY. 



thin seams of clay. Occasionally, carbonaceous clays crop out in ravines 

 and gullies, with indications of coal, but no workable deposits have as yet 

 been opened. North of Saint Mary's Station, the beds strike north 70° tu 

 '(5° west, and dip 16° to 20° to the northeast ; near Dana, they strike nortu 

 55° to 60° west; and, still farther eastward, strike north 35° east, but with 

 the same dip. 



Over this area of Laramie strata are dotted, in the spring and early 

 summer, numerous small ponds and lakes, which, in many cases, suffer com- 

 plete evaporation during the dry season. As the country is very poorly 

 drained, and the clays highly impregnated with saline matter, most of the 

 waters are strongly alkaline, and leave behind considerable incrustations. 



From the shore of one of these lakes, south of Percy, a quantity of salt 

 was collected, which, upon being subjected to chemical analysis by Mr. R 

 W. Woodward, yielded the following: ' 



Soluble matter, 48.36 per cent. 



Lime 1.84 1.69 



Magnesia 16.09 15.88 



Soda 20.48 20.65 



Potassa - trace trace 



Sulphuric acid 60.76 60.31 



Chlorine 0.57 0.57 



Phosphoric acid trace trace 



99.74 99.07 

 Combining acids with bases, we have : 



Sulphate of lime ... - 4.45 4.10 



Sulphate of magnesia 48.28 47.56 



Sulphate of soda 46.27 46.46 



Chloride of sodium 0.74 0.95 



99.74 99.07 

 Elk Mountain Eegion. — Nine miles south of Percy Hes Elk Mount- 

 ain, the most northern point of the Medicine Bow liange. Some descrip- 

 tion of the schists and gneisses forming its main mass has already been 

 given, but on its northern slopes are found all the beds from the Coal- 



