112 Cincinnati Society of JSlatural History. 



5. Clay, shale and shal}^ sandstone covered slope, 130 feet. 



6. Soft, laminated clay, interlaid by bands of limonite iron, thin 

 lignite seams, and fossil-wood, 88 feet. 



7. Lignitic black clay, in banks, 32 feet. 



8. Fine-grained conglomerate, 112 feet. 



9. Fine-grained sandstone, 4 feet. 



10. Coarse conglomerate, 7 feet. 



11. Sandstone, 3 feet. 



12. Ferruginous hard conglomorate, 32 feet. 

 Total, 426 feet. 



The soft chocolate-colored, laminated cla3% Nos. 1 and 3 of this sec- 

 tion, has the same composition, color, and characters as the claj- under 

 and above the coal-beds of the Raton mountains and of the Arkansas 

 valley. It is the same, more or less darkly colored by bitumen, which 

 prevails over the whole area of the Lignitic. This cla}' takes the 

 place of the fire-clay so generally underlying the coal-beds of the car- 

 boniferous measures, where, as in the Lignitic, it forms, beside the 

 floor, some bands, clay partings, separating coal strata, and soft shale 

 overl3ing them. The dicotyledonous leaves, specificall}^ identical with 

 those found at Raton mountain and in the Arkansas valley, leave no 

 doubt about the cotemporaneity of these Lignitic measures. 



By far the most interesting member of this section is the conglomer- 

 ate at the top. This is a compound of smallgrains or pebbles, mostly 

 of white quartz, and ofsilex of various colors, varying in size, at least 

 for the largest proportion, from that of a pea to that of the head of a 

 pin. Pebbles as large as a walnut are abundant. This formation, 150 feet 

 thick, at least, is conformable to the strata overhang the coal of the base 

 of the section, and here, as it will be seen at other places, it over- 

 lies immediately thick banks of soft, laminated, bituminous, black cla}^ 

 The materials forming this conglomerate are cemented together b}^ a 

 thin coating of carbonate of lime, which easil}' disaggregates under at- 

 mospheric influence, except in the npper stratum, where the cement 

 has been hardened b}' ferruginous infiltration. Its greater resistance 

 has then locall}^ preserved the whole mass from destruction. These 

 conglomerate cliflTs, which, from the hotel of Colorado springs, arrest 

 the view to the west, appearing like high blufl's of white sandstone, are 

 evidently the mere vestiges of an extensive formation, origin alh' cover- 

 ing the base of the mountains from the Arkansas river, extending far 

 inland to the east. For hundreds of miles the ground of Colorado is 

 formed by its debris. They have given to the soil, that apparent sterility 

 of surface, which is so remarkably' changed into fertility, by the culture 



