580 



SCIENCE PROGRESS 



sandstone composed of angular or rounded grains always con- 

 tains more water in its interstices than a compact sandstone or 

 shale, and must, therefore, flow more readily. 



Fig. 6. 



A more convenient example for illustration is a small rock- 

 fold to be found at Angelier's Bosch, east of Prince Albert, along 

 the north of the Zwartberg Mountains. Here we have a small 



