168 APPENDIX D. GEOLOGY. 



June 24. — The surface was in many places thickly strewn with loose 

 fragments of white carbonate of lime. About seven o'clock we reached, 

 after a gradual ascent, a high, level, and very fertile plain, from which 

 we obtained an extensive view of the surrounding country, which was 

 very hilly and divided by numerous ravines. The plain at its termina- 

 tion presented a long line of high bluffs, composed of horizontal strata 

 of drift, finely laminated sandstone, white limestone, conglomerate, gyp- 

 sum, and red and yellow clay, (see Section No. 9.) The red clay was 

 thickly interstratified with thin seams of gypsum. From the drift I 

 obtained specimens of agates, fossil-wood, jasper, and chalcedony. Soil 

 and subsoil the same as before. 



June 25. — The country travelled over to-day was very hilly and 

 broken, being much divided by long, narrow ravines, with nearly per- 

 pendicular sides, composed of red clay — some of them being over one 

 hundred feet deep. In many places we were surrounded by high bluffs. 

 The drift was found to be unusually abundant — in some places fifty feet 

 thick, and much coarser than before met with. At about eleven o'clock 

 we came in sight of the valley of the Dogtown river. On either side 

 it was bounded by long lines of buffs, in composition similar to those 

 previously noticed, and varying in height from one hundred to one hun- 

 dred and fifty feet. From the drift we obtained specimens of chalce- 

 dony, agates, silicified wood, and jasper, besides a large number of shells 

 of the same character as those observed on the 2 2d instant. The beds 

 of the different streams crossed were covered with black ferruginous 

 sand. Soil good, consisting of a rich black mould ; subsoil argillaceous. 



June 26. — For the first few miles the country was hilly and very 

 much divided by ravines, some of which were two hundred feet in depth. 

 The strata exposed by them were invariably found to consist of hori- 

 zontal layers of red clay, gypsum, and drift, each occupying the same 

 relative position as shown in Section No. 9. 



June 21. — Formation the same as on yesterday. At ten o'clock we 

 came to Dogtown river, the bed of which was composed of yellow sand, 

 intermixed in some places with red clay, and covered with small shining 

 particles of gypsum. I observed in the drift large quantities of red and 

 yellow jasper. Soil fertile ; subsoil argillaceous. 



June 28. — Saw a large number of drift-hills, varying in height from 

 fifty to one hundred and fifty feet. After travelling a few miles we 

 again came to the borders of the " Llano estacado," which here presented 

 a long line of bluffs six hundred feet high, and composed of horizontal 

 layers of drift and sandstone, interstratified with white limestone. From » 



