ar. JOHN.] 



PALEOZOIC AREAS. 477 



manner by the steeply tilted beds that lap up on the sides of the mount- 

 ain, there is, perhaps, no necessity for referring the results to more vio- 

 lent manifestations of disturbance than those accompanying the very 

 gradual and long-continued elevatory movement which, only allowing 

 time, would be sufficient for the elevation of the mountain into its pres- 

 ent magnitude, and the erosion of the predetermined stream-bed to its 

 I)resent depth in its passage across the disturbed area. 



Although the southeast corner of our district includes the Archaean 

 zone of the Wind Eiver Eange, at no point did opportunity offer to pen- 

 etrate this interesting region. But we know its general features from 

 the early explorations of Dr. Hayden, who reported the northern con- 

 tinuation of the watershed north of Union or Warm Water Pass to be 

 enveloped up to a high altitude by Tertiary deposits and capped by vol- 

 canics, as we found to be the case in the neighborhood of Togwotee Pass, 

 where not the vestige of Archaean nor Palaeozoic rocks, in sitUj were ob- 

 served. 



PALEOZOIC AEEAS. 



Besides the Palaeozoic belts that encompass or partially surround and 

 reach up on Archaean areas, in whose elevation they have hkewise par- 

 ticipated, there are considerable zones of rocks belonging to this era in 

 various parts of the district, the upheaval of which, although accompa- 

 nied by extraordinary displacements, did not bring to view the crystal- 

 line basis-rocks. The gTeater portion of the south and southwest is oc- 

 cupied by upheavals of the latter class. But it will perhaps facilitate 

 the review of this series of formations briefly to define the geographical 

 position of all these areas. Commencing on the western border, they 

 may be considered in the progTessive order of their occurrence to the 

 east. 



In the extreme southwest, the monoclinal ridge which finishes off 

 the northern terminus of the Mount Putnam, or more properly the 

 Portneuf Eange, exhibits apparently the full series of Palieozoic forma- 

 tions, as they are here developed, reclining upon the eastern flank of 

 what was doubtless once an anticlinal fold, whose western decliAity 

 was denuded in the course of the erosion of the great basin of the 

 Snake. 



To the northeast of the Putnam hills a few miles, these fonnations 

 have been brought up in an approximately parallel low ridge southwest 

 of the Blackfoot, in which the upper siliceous beds of the Carboniferous 

 have been tilted into nearly vertical position — indeed, sometimes past 

 verticality — where the quartzitic ledges give origin to the rather promi- 

 nent crests of Higham's Peak. A few miles north of the latter point the 

 ridge is comx)letely cut down in the canon of the Blaclifoot, in the walls 

 of Avhich Dr. Hayden, in 1871, observed nearly the full series of Palaeo- 

 zoic roclcs, dipping to the eastward and covered by the upraised volcau- 

 ics. Although this ridge presents a rather well-defined topographic 

 feature, geologically it is much comphcated, the southern and northern 

 folds in which these rocks appear belonging to two very distinct sets of 

 dynamical actions which intersect one another nearly at right angles, 

 the southern of which belongs to the Mount Putnam system of folds. 



In the much-disturbed region of the Blackfoot Eange, next east, and 

 the low parallel basin ridges southeast of the southern extremity of that 

 range, with a single exception, no rocks of au earlier date than the Car- 

 boniferous were met with. This belt is almost coextensive with the 

 length and breadth of the range, and at the south it embraces a limited 



