124 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



Half a mile beyond milepost 315, at the crossing of a small creek 

 which enters the river from the right, the base of brilliant light- 

 red sandstone is exposed. This sandstone is Triassic in age and is 

 much more showy in color than any other rock which the traveler has 

 seen since he left Canon City. On account of its striking color 

 attempts have been made to utilize it as building stone, but gener- 

 ally it is so easily affected by the weather that in a few years the 

 cornel's are rounded off and even great holes are etched in the solid 

 blocks. TMiere first seen these beds dip about 45° W.. but the dip 

 flattens in a short distance to about 25°.^^ Beyond milepost 316 the 

 top of the bright-red beds may be seen on both sides of the river. 

 On the right ihej extend down the hillside in a great curve, but on 

 the left they run along the face of the bluff with only a slight dip 

 downstream. 



The rocks that oA'erlie the bright-red sandstone are variegated 

 in color but are predominantly green and maroon. They make up 



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spoo 



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Triassic sandstones ^Gunnison formation 



Dakota sandston^ 



"-^ar^oTj-Top^-^^-^--,- 



Figure '<i-.- — Sketch section across the syncline at Wolcott on a line from east to west. 



what is called the Giumison formation, so named from its outcrop 

 in the valley of Gunnison River. The upper part of this forma- 

 tion is without doubt the same as the Morrison formation on the 

 east side of the mountains, but its lower part probably includes 

 rocks that are not found on that side. The Gunnison formation 

 here contains much soft shale and clay but includes also some beds 

 of resistant sandstone. At this place the formation has been so 

 much crushed that its thickness can not be estimated, but at other 

 outcrops in this vicinity, where it is undisturbed, it is about 220 

 feet thick. The discovery of the remains of some very wonderful 



**The peculiarities and irregulari- 

 ties of the dips in this part of the 

 valley can be best understood by refer- 

 ence to the map on page 134. This map 

 shows that the river here cuts di- 

 agonally across the rim of a sag or 

 basin in the rocks (not a surface ba- 

 sin), the lowest part or axis of which 

 is crossed by the railroad a mile or 

 so farther north toward Wolcott. On 

 the eastern rim of this basin the rocks 



stand on edge, as shown by the ac- 

 companying diagram, but they flatten 

 rapidly as they pass below water level, 

 and as seen farther on they lie nearly 

 flat along its axis. 



The meaning of the dips is well illus- 

 trated in the accompanying sketch (fig. 

 32), which shows the rocks as they 

 Would appear in a deep trench cut ver- 

 tically from east to west through the 

 fold. 



