290 DESCEIPTIVB GEOLOGY. 



Upper Coal-Meamre limestones. The bedding of these Hmestones is con- 

 cealed by surface accumulations, and, in general, can only be studied in the 

 cuts of the deeper canons. In the little peak, however, between the heads 

 of Ashley Creek and Brush Creek, just west of the Sheep Creek Trail, the 

 strata of Carboniferous limestone were found dipping nearly 25° to the 

 southward, showing signs of metamorphisni in their red coloring, and indi- 

 cations of the presence of vein material in the fragments of mineralized 

 quartz on the surface. This steep dip would seem to indicate some little 

 local disturbance at this point ; but south of the line of contact of the Weber 

 Quartzite with the Upper Coal-Measures, from a little west of this point to 

 a little east of Ute Peak, these beds seem to be approximately horizontal, 

 forming a flat bench country, into which the streams flowing south have cut 

 deep canons. From the accumulation of rounded quartzite pebbles on its 

 surface, it is probable that it was once covered by the beds of the Wyoming 

 Conglomerate, but the only portion of this plateau where it was possible to 

 prove the actual existence of this conglomerate was to the south of Cold Spring; 

 Here on the bluffs overlooking Brush Creekwas obtained a section, 200 to 

 300 feet in thickness, of a coarse gravel conglomerate, full of large rounded 

 boulders of the Uinta quartzite, showing, as elsewhere, no bedding or 

 structure-planes, and covering unconformably the upturned edge of the Meso- 

 zoic beds. Along the southern edge of this bench or plateau country, the 

 Upper Coal-Measure strata, as exposed in the canons cut by the streams flow- 

 ing into Ashley and Brush Creeks, are seen to dip off steeply to the southward, 

 this line of flexure marking approximately the northern limit of the Ashley 

 Creek Basin. 



On the surface of this bench region, near Geode Canon, was found, in 

 a pebble of red jaspery quartzite, a remarkably well-preserved specimen of 

 Spirifer cameratus. From its position, its origin was evidently the Weber 

 Quartzite beds of the interior of the range, and the character of the matrix 

 would indicate that the stratum in which it was deposited belonged to the 

 middle of the series. With the exception of a Spirifer imbrex found in debris 

 from beds of the Weber Quartzite at the head of Bear JRiver (Chapter III), 

 this is the only palseontological evidence obtained as to the age of the great 

 body of rock forming the core of the range. • 



