PENNSYLVANIAN-PERMIAN GLA CIA TION 



481 



on the largest face. While actual continuity of the striae is broken 

 in the farthest recess of the re-entrant where surface waters, after 

 heavy rains from the slopes above, have concentrated and worn 

 them away, there seems little reasonable doubt of their original 

 continuity. The surface of the granite has been roughened by 



Fig. 10. — View of grooved granite, overturned block 



Fig. II. — View of grooved and striated granite 



present weathering processes, but examples a short distance to the 

 north show grooves with smooth and polished surfaces. 



The manner in which the grooves and striae entirely encircle 

 small isolated stacks and bastions of granite is shown in Figures 12 

 and 13, which are views of the same rock taken from opposite sides. 

 Although this particular example has been incidentally referred to 



