OURAY UNCONFORMITY 457 



This discordance in dip continues through the cliff face almost to the 

 Blowout creek, as is clear from plate 83. 



In plate 84 is reproduced a view of the unconformity in the cliffs either 

 side of Cascade creek, as seen from the cliffs above Ouray on the west 

 side of the river and north of Oak creek. The point of view is but little 

 below the plane of unconformity and the discordant, greater dip of the 

 Carboniferous strata is very evident. 



In following the unconformity from the Amphitheater northwest it is 

 found that the strata below the Triassic conglomerate belong to the Her- 

 mosa formation nearly to Cascade creek. Just before reaching that 

 stream a massive pale reddish sandstone appears, the highest fossilifer- 

 ous bed of the Hermosa occurring directly under it. This stratum of 

 sandstone is approximately 100 feet thick, exceptionally massive, and as 

 a similar bed appears likewise on the west side of the Uncompahgre, 

 just above the uppermost fossil-bearing limestone, the base of this red 

 sandstone is assumed as limiting the Hermosa formation. 



The heavy sandstone just mentioned underlies a wooded bench on the 

 shoulder adjacent to the Blowout, and it is there separated by only a 

 few yards from the Triassic conglomerate above it. Beyond this point, 

 on the east side of the river, the relations are obscured for some distance 

 through the Blowout porphyry intrusion and a great amount of land- 

 slide and other debris, and we now turn to the exposures on the west 

 side of the Uncompahgre as best illustrating the relations of the Tri- 

 assic to the Red beds proper of this district. 



On the northwest of the town of Ouray rise cliffs even more precipi, 

 tous than those to the east, but not quite so high. The lower half of 

 these cliffs exhibits Hermosa strata, but the upper part contains many 

 sandstones and shales of stronger red tones than can be found in the 

 Cascade Creek section. No unconformity appears in these cliffs as seen 

 from the east. On searching for the Triassic horizon, it is found a little 

 above the main cliffs and below a pronounced bench of glacial molding. 

 This bench is carved at about the Triassic horizon, descending gradually 

 northward with the dip of the strata. Its floor is uneven in detail, more 

 or less debris-covered and timbered, but the white La Plata sandstone 

 outcrops in many places just back of it, and the Triassic conglomerate 

 appears below it, within a few yards in most places. Where this bench 

 begins, on the north side of Oak creek, the Triassic conglomerate occurs 

 at about 8,900 feet, the same level it occupies adjacent to the Blowout on 

 the east; but fossiliferous strata of the Hermosa do not underlie it here, 

 and in fact 400 to 500 feet of grits, conglomerates, and deep red sandy and 

 micaceous shale intervene before the Hermosa limestones appear. The 

 Hermosa and overlying Red beds in the cliffs dip 15 to 20 degrees 



