102 Cretaceous. 



5. Clay, shale and shaly 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 congiomorate, 32 feet. 

 Total, 426 feet. 



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

 tion, has the same composition, color, and characters as the clay under 

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

 valley. It is the same, more or less darkl}' colored by bitumen, which 

 prevails over the whole area of the Lignitic. This clay 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, sohie bands, clay partings, separating coal strata, and soft shale 

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

 those found at Raton mountain and in the Arkansas valle}^, 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 small grains 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 foi-mation, 150 feet 

 thick, at least, is conformable to the strata overlying 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 clay. 

 The materials forming this conglomerate are cemented together by a 

 thin coating of carbonate of lime, which easily disaggregates under at- 

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

 has been hardened by ferruginous infiltration. Its greater resistance 

 has then locally preserved the whole mass from destruction. These 

 conglomerate cliff's, which, from the hotel of Colorado springs, arrest 

 the view to the west, appearing like high bluffs of white sandstone, are 

 evidently' the mere vestiges of an extensive formation, originally 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 



