PEOVO oaS^on. 347 



recognised came from a dark -blue, thinly-stratified, somewhat shaly lime- 

 stone ; the fossils from the more massive beds, in general, being too difficult 

 to obtain, except from broken masses and boulders. The dip, as has already 

 been said, gradually changes in ascending the canon, from perpendicular 

 to 45°, and finally to about 25° east. In the longitudinal valley, at the 

 head, the outcrops are obscured by soil accumulations, but, in the main 

 ridge above, blue and gray limestones, generally rather lighter in color 

 and less close in texture, are found dipping about 20° to the east. From 

 these were obtained other Coal-Measure fossils, which seem to indicate a 

 somewhat higher horizon, though it may be remarked here, that in general 

 the Coal-Measure fossils which are found extending through a vertical range 

 of nearly 15,000 feet in this region, do not, as far as yet known, mark any 

 horizon with sufficient distinctness to afford a sure guide, apart from the 

 general stratigraphical and petrological considerations, which have been 

 the main basis of the conclusions arrived at. The fossils obtained in this 

 upper ridge were : 



Streptorliynclius crenistria. 

 ■ Produdus Nehrascensis. 



Spirifer lineatus. 



Athyris suUilita. 



Aviculopeqten, sp.? 



A thickness of over 10,000 feet of limestones would be given in this 

 section but for the faulting in the longitudinal valley, whose amount, how- 

 ever, the conditions do not afford means of estimating. To the south of 

 Provo Peaks, this upper faulting apparently disappears; and at the mouth 

 of Hobble's Canon, a simple monoclinal fold, with an eastern dip of 25° in 

 the Wahsatch limestones, is presented. On the eastern slopes of the ridge 

 are found quartzites, whose position refers them to the Weber Quartzite; 

 they are much obscured, however, by d(ibris, and soon concealed by the 

 unconformable Tertiary and Cretaceous beds, which, in this portion of the 

 range, extend well up on its eastern flanks. 



Provo Canon is a remarka.bly straight deep gorge, extending at right 

 angles to the strike through the main ridge, and affording an outlet to the 

 very considerable stream of this name, which takes its rise in the Uinta 



