SURVEY OF COLORADO AND NEW MEXICO. 51 



It may be that the older rocks are elevated under the debris close to 

 the foot of Wet Mountairi, but no beds older than the cretaceous can be 

 seen. The upper cretaceous beds extend up close to the mountains, 

 oftentimes capped with the tertiary, inclining not more than live to ten 

 degrees. 



At the head of Hardscrabble Creek the ridges of upheaval or " hog- 

 backs" begin to show themselves again in a narrow belt which raj)idly 

 widens out, so that before reaching Greenhorn Creek they have spread 

 out to a width of several miles. 



On Eed Creek, which is about eight miles south of Hardscrabble, 

 there is the finest exhibition of the yellow massive chalk passing down 

 into the gray marl of ISTo. 3 that I have seen south of the Upper Mis- 

 souri. In the channel of this stream and its branches there are vertical 

 walls eighty to one hundred feet high, looking much like irregular mason 

 work. Some of the gray portion is a very hard limestone, and contains 

 a large, apparently un described species of Inoceramus.. Between lied 

 Creek and St. Charles there are other exhibitions of the cretaceous 

 rocks, but especially of the quartzose sandstones of No. 1, which, at the 

 foot of the mountains, are cut through by the numerous little branches 

 in a most picturesque manner. The little streams run through vertical 

 walls eighty to one hundred feet high, forming most interesting canons, 

 and revealing all the peculiarities of structure of this sandstone. Some 

 of it is coarse and friable, other portions are compact silicious rocks; 

 others, a pebbly conglomerate. All the illustrations of irregular layers 

 of deposition, ripple or wave markings peculiar to sandstones, are found 

 here; also, admirable examples of slick ensides. The jointage, which is 

 very marked, is vertical, at right angles to the lines of stratification, and 

 most essentially assists atmospheric agencies in wearing it away, so that 

 the sides of the walls are often very rugged, and immense cubical blocks 

 have fallen down by the water's side. 



The different formations all along the flanks of the mountains are 

 exposed by the upheaval of the mountains, and lie in belts or zones, 

 which are sometimes concealed for a distance by recent tertiary deposits 

 or by debris; or they a,re narrow or wide at different points, and their 

 conditions are only to be determined by personal inspection. 



At the head of St. Charles Creek all the rocks incline gradually down 

 from the mountain side. 'No. 1 dips thirty degrees and slopes gently 

 down until it reaches a nearly horizontal position in the plain. West 

 of this first high ridge is a fine valley in Avliich are beautiful, cultivated 

 farms. The red beds are well shown, and I have no doubt but that the 

 carboniferous limestones are exposed on the sides of tlie mountains. 



Just before reaching Greenhorn Creek all the small ridges and the 

 first high one run out in the plain, and the mountains flex around 

 toward the southwest to form the notch for the Sangre de Christo Pass. 

 The ridges of elevation and the side ranges, like Wet Mountain, have a 

 general trend about northwest and southeast, and all the lower ridges 

 run out in the prairie, and Wet Mountain ceases at the pass. 



On the north side of Greenhorn Creek, near Hicklin's Eanche, No. 2, 

 is a rusty arenaceous limestone, full of shark's teeth, mingled with a 

 mall species of Ostrea. The arenaceous limestone is attached to a gray, 

 ne-grained sandstone, and is rather concretionary in form. Just on 

 the opposite side of the creek, and apparently holdiug a higher position, 

 are the quartzose rocks of No. 1. Around the south end of the Wet 

 Mountain, the cretaceous beds, Nos. 2 and 3, in the form of dark clay, 

 and j^ellow, chalky shales, present bench-like hills, extending down at 



