STRIKE AND DIP. 55 



the southern portion of the Arcli.ipan district. Tlieir principal mass is in 

 the Harney Peak region, and has an area twelve miles in diameter north 

 and south and about seven east and west, besides this central mass others 

 of less magnitude are found, diminishing in size as the distance from the 

 peak increases. The smaller bodies occur at the west and east, but jiarticu- 

 larly at the south. All of the granite masses whose relations could be 

 closely examined were found to be parallel with the stratification of the 

 schistose rocks, and when their structure Avas readily discernible were seen 

 to be lenticular in shape. 



The strike or trend of the schists is in general north and south, but it 

 varies from northeast and southwest to northwest and southeast, and south 

 of Harney Peak in the region of French Creek and in the park country 

 immediately south of that stream even this range of variation is exceeded. 

 Here the strata are found to sweep around from a strike on the headwaters 

 of Castle Creek of north 30° west to an east and west course on French 

 Creek in the vicinity of the stockade, returning again on the east side of the 

 Harney Peak range to their usual north and south direction. In the 

 vicinity of the stockade the varying strike is marked b)' bold ridges of 

 granite, which bend around and change their strike as indicated. 



The dip of the schists is usually very high and often vertical, though 

 occasionally by local variation it becomes quite low. In several places a 

 difference of dip was noticed between the schistose rocks on the west and 

 the slates on the northeast side of Harney Peak, the former being toward 

 the west and the latter toward the east, but the number of observed points 

 of variation was not sufficient to warrant the statement that this difference 

 is a persistent feature of the relation of the two series of rocks. On Castle 

 Creek and on the other heads of Rapid Creek the dip is from 55° to 85° 

 west, but in going southward and eastward there is found a change cor- 

 responding to the change in strike already noticed on French Creek, and 

 the dip becomes slightly southward from the vertical. On the headwaters of 

 Red Caiion Creek it is 70° to 80° south; on lower French Creek 45° south. 



The vertical position of the schists and their highly micaceous nature 

 cause them to decompose readily and uniformly, giving a peculiarly 

 smooth and unbroken surface to the topography and producing those beau- 



