IP s t e I s i a 293 



There are some instances of a combination 

 of sandstone and conglomerate pools. In one 

 case, a mass of conglomerate stands surround- 

 ing a depression in sandstone. In another case, 

 one side of the pool was sandstone, and the other 

 was conglomerate, the sandstone being more 

 worn than the conglomerate. In one region of 

 conglomerate, is found a number of good sized 

 pools, exhibiting the characteristics of sand- 

 stone pools. Upon examination it was found 

 that these pools all have sandstone bottoms, 

 surrounded by masses of conglomerate. 



Pools in shale are found rarely. They are 

 very long and narrow, following the lines of 

 stratification (Plate XXV. fig. 2.). They are 

 shallow in comparison with sandstone pools, 

 owing to the greater difhculty of erosion of the 

 hard crystalline rock. Very few large pools of this 

 class are seen. Only occasionally boulders 

 occur in shale pools, and generally in a posi- 

 tion indicating that they have rolled in from 

 the high banks above, and are not native to 

 the pool. The fauna and flora usual to the 

 sandstone pools are present, but in smaller 



