164 APPENDIX D. GEOLOGY. 



of chalcedony, agate, and jasper. No rock of any description was 

 observed at a greater distance than a few feet from the base of the 

 mountains. Soil thick and fertile; subsoil loamy. 



May 30. — The mountains did not differ materially in appearance or 

 structure from those before observed ; at a distance, a few of them 

 appeared to present a columnar structure ; but upon a nearer approach 

 this was found to be owing to divisional plains, or master-joints, with 

 weather-worn and rounded edges. I observed to-day a number of clear 

 springs ; the water of several being tasted was found to be alkaline. 



In the prairie we observed several circular elevations, varying from 

 one hundred to one hundred and thirty yards in diameter, and ascending 

 in some places to the height of three or four hundred feet above the 

 general level. Upon examination, their mineralogical composition was 

 found to be the same as that of the neighboring mountains. Within a 

 few feet of one of these, a small ravine exposed to view a horizontal 

 stratum of soft ferruginous sandstone. Soil and subsoil the same as on 

 yesterday. 



May 31. — The mountains presented the same general appearance as 

 on yesterday. From their surface were exhibited a large number of 

 veins, varying in thickness from an inch to a foot and a half, and com- 

 posed of greenstone, quartz, and hornblende. The prairie was here and 

 there dotted with a number of conoidal elevations, varying in height 

 from twenty to one hundred feet. In composition they agreed in every 

 respect with the neighboring mountains, with which in origin they 

 appeared to be cotemporaneous. From the drift I collected specimens 

 of fossil-wood. The water of springs issuing from the mountains I 

 found, upon test, to be alkaline. 



June 1. — Red river as observed to-day runs between low bluff blanks, 

 composed of red clay. Its bed was in some places thickly strewn with 

 large detached masses of granite, all presenting a highly water-worn 

 appearance, and seeming to have been derived from a neighboring 

 mountain. Soil and subsoil the same as before. 



June 2. — Immediately upon leaving the Witchita mountains, we lost 

 all traces of drift and other igneous rocks. Red river as observed to-day 

 runs between high bluff banks, composed of horizontal layers of red, 

 yellow, and blue clay, and finely laminated sandstone ; the latter being 

 inters tratified with thin seams of saccharoid gypsum, (see Section No. 4.) 

 About a mile from the river we observed two conical hills — one fifty 

 and the other eighty feet in height^— composed of horizontal layers of 

 sandstone, interstratified with thin seams of gypsum. From them I 

 obtained specimens of selenite. Soil and subsoil loamy. 



