SLIGKENSIDES. 73 



were carefully looked for. Hand fragments may be found anywhere along 

 the separating line, showing the micaceous schist on one side and the granite 

 on the other, separated by a line that can be traced with a needle point. 



In several instances the contact surface of the granite was found beau- 

 tifully polished or slickensided, and many others doubtless escaped notice 

 because of the easy disentegration of the granite. One particular case is 

 worthy of specification. It was seen near French Creek, as we approached 

 it from the headwaters of Spring Creek. An exposed surface of one of the 

 granite masses stands there four or five feet above the incasing schist, and 

 in fragments extends a distance of twenty feet. This surface is as beauti- 

 fully smoothed and polished as any glacial planing I have ever seen, and 

 the resemblance is so striking that it was taken at first to be a glaciated 

 surface. These smoothed surfaces are produced by the movements of the 

 rocks against each other, and as the granite is harder than the schist, it 

 became polished just as a tool of hardened steel is polished on a grindstone. 



West of Harney the strike of the rocks is from north and south to 

 northwest and southeast, and we find the inclosed granite masses running 

 in the same manner. Southward, on French Creek at and above the stock- 

 ade, the strike of the schists is changed, and with them the inclosed granite 

 ridges run nearly east and west. Southwest of the stockade, in Custer 

 Park, the schists and granite run north and south, and this strike is ex- 

 changed in the eastern part of the Park region for an east and west, which 

 bends around on the east side of Harney, becoming the customary trend 

 toward the north and northwest. These features in the strike of the rocks 

 have already been noticed in the description of the general features of the 

 schist area, and need here no further comment. In all the region where the 

 granites are included in the schists they rise abruptly above the general 

 level; for though they are somewhat easily disintegrated, they are surpassed 

 in destructibility by the schists and the latter have been much more rapidly 

 removed, leaving the granite prominent. 



The masses vary greatly in size. Sometimes they are merely veins 

 an inch or two in thickness and of very limited extent. More commonly, 

 however, they are 25 or 50 or more feet in width, and several hundred feet 

 or several hundred yards in length. The larger peaks or ridges are often 



