GEOLOGICAL SURVEY OF THE TERRITORIES. 325 



markings, appear to belong to the lower part of the fucoidal sandstone, 

 the remains of marine plants often resembling mud-marks of various 

 kinds. The i^resence of a specimen of Inoceramus in the upper part of 

 the strata is an apparent contradiction to this conclusion. The matter 

 is left aside for future discussion. 



§ 3. Colorado Springs to Denver. 



From Pueblo northward no trace of the Lignitic is seen along the 

 mountains till near the southern base of a range of hills, the Colorado 

 Pinery, which, in its eastern course, at right angles from the primitive 

 mountains, forms the divide of the waters between the Arkansas and the 

 Platte Rivers.. 



The succession of the Cretaceous strata is clearly marked on the 

 banks of Monument Creek. In following it up from Colorado Springs 

 the formation can be studied to the top of the black shale No. 4, and 

 above this to a bed of brownish sandstone, separated from the black 

 shale by thin layers of Tuten clay and soapstone, where the last remains 

 of Cretaceous animals, especially fragments of BacuUtes, are still 

 abundant. Over this is the sandstone, barren of any kind of remains, 

 overlaid in the banks of the creek by a bed of fire-clay, or very soft 

 chocolate-colored shale, which marks the base of the following section at 

 low-water level of the creek : 



Feet. 

 1. Brown laminated fire-clay, or chocolate-colored soft shale, a componud of re- 

 mains of rootlets and leaves and branches of undeterminable conifers 2 



2. . Coal, soft, disaggregating under atmospheric influence 2 



3. Chocolate-colored clay-shale, like No. 1, with a still greater proportion of 



vegetable debris 6 



4. Soft, yellowish, coarse sandstone in bank 8 



5. Clay, shjile, and shaly sandstone covered slope ' 130 



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



seams, and fossil-wood , 88 



7. Lignitic black clay, in banks 32 



8. Fine-grained conglomerate ". 112 



9. Fine-grained sandstone v 4 



10. Coarse conglomerate 7 



11. Sandstone 3 



12. Ferrugi nous hard conglomerate 32 



426 



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

 section, has here the same composition, color, and characters as the clay 

 under and above the coal-beds of the Eaton Mountains and of the 

 Arkansas Valley. Indeed, I have seen it the same, more or less darkly 

 colored by bitumen, however, in connection with coal-beds, over the 

 whole area of the Lignitic which has been passed in my exploration. 

 This clay takes the i)lace of the fire-clay so generally underlying the 

 coal-beds of the Carboniferous measures, where, as in the Lignitic, it 

 forms,besides the floor, somebands,clay-i)artings, separating coal-strata, 

 and soft shale overlying them. It has also been formed in the same 

 way by immersed fresh-water plants, or true water-plants like Characcce, 

 by the innumerable divisions of the roots of trees living along or within 

 the swamps, and by the cUbris of the trees, which appear to have been 

 mostly conifers. The fragments entering into the composition of this 

 clay-shale are much more divided and obscured by maceration than the 

 remains preserved in sandstone or sandy shale, and, except for a few 

 branches of conifers, I have not yet been able to determine any of them 

 in a satisfactorv manner. 



