SURVEY OP COLORADO AND NEW MEXICO. 63 



wMtisli, yellowish, &c.; dip 45° to 55°; thickness two hundred and 

 thirty-live feet. 



9. E-ather line grained grayish sandstone. This bed has x^assed a 

 vertical position so that the dip is southwest 75° ; thickness fifty feet. 



10. Yariegated sands, light brick-red, dull purple, reddish brown 

 and light gray. The dull purplish sands, ten feet thick, are amygdaloidal, 

 full of almond-shaped nodules and cavities. 



10. Alternate beds of light yellowish, grayish sandstones, and arena- 

 ceous shales, very much variegated. 1st. Sandstones, fifty feet; 2d. 

 Yariegated arenaceous shaley clays, sixty feet ; 3d. A curious wall of 

 sandstone which forms a conspicuous point by turning the current of 

 the creek at a right angle and running across, in a nearly vertical posi- 

 tion, but having the natural dip northeast ; dip 85°. This curious wall 

 will always be noticed by travelers. It passes up gradually into the 

 variegated sandy shales or laminated sandstones that form ISTo. 12. 



12. Among these laminated sandstones is a sort of silicious mud 

 layer that is filled with the casts of a species of 3Iytilus, which leads me 

 to snspect them to be Jurassic. There is also a layer filled with fragments 

 of fossils — a saurian tooth, &c. The beds continue with a reddish tinge 

 varying from a greenish brown to a dull purplish tint, with every degree 

 of texture. Some of the layers of laminated sandstone are a light ashen 

 gray, some of nodular and x)ebbly sandstone, also with a tendency to 

 lamination — 300 feet. 



13. A rather massive gray sandstone, some portions amygdaloidal 

 or nodular, some fine grained and some slightly calcareous. Some of it 

 is good for building purposes, flagging stones, «&c. Two layers of ashen 

 gray clay — first six feet, second three feet. 



14. Yery dull purplish clays, with some harder layers of sandstone, 

 thin, of an ashen gray — 30 feet. 



15. Like bed 13, only more laminated, portions massive and fine; 

 some layers a rusty yellow, with impressions of woody stems and trunks, 

 not jointed but ribbed (!) ; passing into a dull purplish red massive 

 sandstone, with a very irregular laminse of deposition, some of it pebblv 

 and nodular— 200 feet to 300 feet. 



10. Keddish laminated shale, with some greenish or ashen spots, 

 some nodules, but slightly variegated with seams of fibrous gypsum fol- 

 lowing cleavage — 300 feet. 



17. Yellowish gray, rather fine grained, massive sandstone; i)or- 

 tions of it with a reddish tinge ; cleavage joints shown well — 100 feet. 



18. Eeddish brown shales slightly gypsiferous — 25 feet. 



19. Massive sandstone, like 17 ; dip 75° to 80^—100 feet. 



20. Yery dull purplish drab, somewhat nodular, arenaceous clays with 

 some hard layers of sandstone, mostly dark brown, and very variable 

 in texture. This bed belongs to the lower cretaceous, or is a bed of pas- 

 sage— 200 to 300 feet. 



21. The sandstone " hog-back," regarded as lower cretaceous No. 1. 

 A very conspicuous formation in this region. A portion of ISTo. 1 stands 

 quite vertical, while other portions incline from 60° to 80°. It is in part 

 a coarse sandstone and fine aggregation of pebbles, i3assing up into a 

 fine grained whitish sandstone, two hundred feet thick, passing to a series 

 of alternate thin layers of dark laminated clay and mud sandstones, 

 with all sorts of markings, indicative of shallow water, mud flats, &c. 

 The dip of some of the layers passes a vertical at the top. 



22. Then coine the dark clays of No. 2, slightly arenaceous at first, 

 passing up into black shales, then into the blue marly limestone with an 

 abundance of Inoceramus. Some of the layers of blue limestone have 



