74 OAKHdNlFKKol'S KOKMATKlNS AND KAUNAS OF COLORADO. 



(>r i"il(;ii('()us matter. At the 1ii>:k1 of Taylor River the following section, descending, 

 wii.s ohtaincil: 



Feet. 



1. SancLstonc, very dark, somewhat vesicular in portions; contains much calcspar and some iron 



ore. It is not at all (certain that this is Silurian. In many respects it is more nearly allied 

 to the Carboniferous above 20 



2. Sandstone, completely converted into quartzite; fine grained, light gray 20 



3. Shale, arenaceous aliove, white on fresh fracture, bright buff on weathered surface; lielow 



quite ai'gillaceous, with layers of cone in cone, and in parts iiuite micaceous 18 



4. Sandstone, (piartzite, coarse above, line below; contains much chert, usually in lenticular 



nodules, but sometimes united so as to form continuous layers; this chert is mostly bluish- 

 black, but occasionally light colored and dendritic; geodes of quartz are numerous, 1 to 3 

 inches in diameter. The stratum is very thick bedded 7.5 



.5. Sandstone, slightly altered, grayish yellow, fine grained, micaceous, shaly, with thin films of 



quartz along cleavage planes 45 



(i. Sandstone, on top completely altered, and fcjr 20 feet has fracture like flint, is perfectly smooth, 

 without grain, but shows clearly the lines of deposition; color, bluish white. Lower down 

 is less altered, and the rock is a coarse-grained, compact sandstone. At the base is a con- 

 glomerate (juartzite, the peljbles being usually as large as a pea. This stratum rests upon 

 coarse granite 70 



"At the head of Taylor Canj'on No. i is quite light in color, and the chert is 

 almost white, while at the head of Tumichi Creek it is as described in the section 

 above. At the head of the canyon No. 5 is greatly increased in thickness, and is of 

 Yenetian-red or burnt-umber color, and has the same character where exposed along 

 the headwaters of Tumichi Creek. Along the old miners' trail from Taj'lor to East 

 River this section is occasionally seen, and diflfers from that given above only in 

 that No. 3 becomes quite calcareous, being at one locality' an argillaceous limestone. 

 Nos. 3 and 6 are xevy characteristic and persistent throughout this region. In the 

 southern portion of this area the Silurian has always been thin. On the lower 

 portion of Tumichi Creek and at two localities west from the Indian agency isolated 

 exposures are seen where erosion has removed the overlying eruptive rocks. The 

 rocks here belong wholl}' to No. 6 of the section above, and have a total thickness of 

 not more than 70 or SO feet." 



The thickness* of this series, which aggregates only 248 feet, and its generally 

 siliceous character, would lead one to believe at first that the whole section represents 

 the Sawatch quartzite alone. On the other hand, it is peculiar that there appear to 

 be no calcareous beds below the Carboniferous suitable to be referred to the Yule 

 limestone. It is possible that Stevenson grouped the Yule limestone with the Car- 

 boniferous limestone, but this can not be ascertained from his descriptions. On the 

 other hand, the lithologic sequence when close!}' compared with the section of the 

 Crested Butte quadrangle is somewhat strikingly similar, though the measurements 

 given by Stevenson are in every case considerably less. The lowest bed. No. 6, is 

 lithologicalh' quite like the basal member of the Sawatch quai'tzite. No. 5, which 

 at the head of the canj^on is reported as having a Venetian-red color, resembles the 

 upper member of the Sawatch quartzite. No. 4 is similar to the basal portion of the 



