212 GEOLOGICAL SURVEY OF THE TERRITORIES. 



slope of the second main ridge there are very few outcrops to be seen 

 through the trees which cover it. At the northwest end there is a dip 

 to the northwest, while at the opposite end the dip is to the southeast." 

 In passing up Tarryall Creek the prevailing dips are to the northeast 

 and southwest. The dip is the same in the country about the North 

 Fork of the Platte, as is sliown by the course of the stream, which is 

 about parallel to that of Tarryall Creek. The latter, as far as could be 

 ascertained, iiows through a synclinal axis. Along the Platte Eiver are 

 high masses rising in dome-shapes above the caiion. The study of this 

 part of the country would require the work of almost an entire season. 

 The different streams should be followed, and this can be done only in 

 the latter part of the season. We were there in June, and I attempted 

 to follow the Platte River, but found it impossible, not only on account 

 of the rough and difficult traveling, but also because the stream was 

 then at its highest point. The whole country is probably archfean. Th'ere 

 may be, and most likely are, points of eruptive material, but, as I have 

 said above, close study will be required to work ui) this district 

 thoroughly. Our time was too limited to do more than take a general 

 glance at the most salient features. We have seen that on the ISTorth 

 Fork and on Tarryall Creek the strike is from northwest to southeast, 

 and that as we go south this changes and becomes northeast and south- 

 west. This change is shown also by the change in the course of the 

 Platte when it enters the upper canon. Before that it flows from the 

 northwest, but in the caiion its course is toward the northeast. 



CHAPTBEII. 



SOUTH PARK — PARK RANGE. 



This chapter will be devoted to the consideration of the remainder of 

 the district lying to the east of the continental divide. This comprises 

 South Park. The park is about forty-five miles in length, and.somewhat 

 irregular in shape, being widest at the southern end, where it is about 

 forty miles from east to west. Its surface is very irregular. As the 

 drainage shows, there is a gradual slope from the northwest toward the 

 southeast. At the northwest end, the elevation is from 9,372 to 9,981 

 feet above sea-level. The elevation of Fair Play is 9,764 feet. As 

 we go east this decreases until we have an elevation of a little over 

 8,000 feet, and as we go south we notice the same gradual decrease. 

 Thus, at the salt-works the elevation is 8,573 feet. In the southern por- 

 tion of the park, the elevation is more uniform than in the northern part. 

 Still, the slope is toward the southeast, and where the South Platte 

 enters the caiion the elevation is only 7,991 feet. There are numerous 

 ridges running through the park, generally parallel to each other. Thus, 

 starting at Fair Play and going eastward, the first is a low ridge a 

 couple of hundred feet in height. Crossing this, we descend to Crooked 

 Creek, and then ascend a second ridge that rises 500 feet above the val- 

 ley. On the east side of this ridge is the valley of Trout Creek, and 

 beyond it a third ridge rising to about the same height, perhaps a few 

 feet higher. East of this is a low rolling country extending for some 

 three or four hundred miles, bounded by a series of rounded hills rising 

 about COO or 800 feet above the general surface. These hills extend 

 for a few miles, and then there is a space having an almost uniform level 



