28 LOESS CREEK. 



in which there was an abundance of good water, where I determined to 

 make our next encampment. On our return we saw a pack of wolves, 

 with a multitude of raven's, making merry over the carcass of the buffalo 

 we had killed in the morning. 



Thinking that the Comanches, whose trail we had seen yesterday, 

 might possibly be encamped within a few miles of us, I this morning- 

 directed Captain McCiellan to take the interpreter and follow the trace. 

 After going about fifteen miles he found one of their camps that had 

 been abandoned two days previous ; and as there was no prospect of 

 overtaking them he returned, after ascertaining that they were travelling 

 a southerly course towards the Brazos river. 



In many places above the Witchita mountains we have found drift of 

 quartz and scoria, but the boulders of greenstone, granite, and porphyry, 

 were only seen below the upper end of the range ; and the nearer we 

 approached the mountains from below, the larger and more angular 

 became the fragments, until, on reaching near the base, large angular 

 pieces nearly covered the' surface of the ground,, thereby leading us to 

 the conclusion that here is the source of the boulders we have seen 

 below the mountains ; whereas the drift found here must come from 

 above, as we have yet discovered no igneous rocks in place since we left 

 the mountains. The formation here is a dark limestone overlaid with 

 loose scoria. The earth Upon the stream is highly arenaceous, and the 

 soil poor. The grass, however, as we have found it everywhere upon 

 Red river and its tributaries, is of a very superior quality, consisting of 

 several varieties of grama and mezquite. 



The range of the grama grass, so far as my observations have ex- 

 tended, is bounded on the north by near the parallel of 36° north latitude, 

 and on the east by about the meridian of 98° west longitude. It ex- 

 tends south and west, as far as I have travelled ; it appears, however, to 

 flourish better in about the latitude of 33° than in any other. As there 

 is generally a drought on these prairies from about the 1st of May to 

 the middle of August, it would appear that the particular varieties of 

 grasses that grow here do not require much moisture to sustain them. 



June 8. — Our route to-day has been over a rolling prairie, in many 

 places covered with the dwarf oak bushes before mentioned. We are 

 encamped upon a creek of clear and wholesome water, which Dr. Shu- 

 mard has named " Loess creek," from the circumstance that the soil 

 upon the stream contains a deposit of land and fresh-water shells? 

 among which are found those of Pupa muscorum, Succiena elonyata, 

 and Helix plebeium, forming a pulverent grayish loam similar to the 

 loess found upon the Rhine. 



