166 



DUNCANSBY STACKS. 



" I have found gneiss, light blue kind of grauwacke, 

 oolite, and oolite conglomerate, in the clay. I know of 

 no rocks in situ to the west similar to these. The blue 

 clay and dark clay is undoubtedly derived from the 

 ordinary rocks of the county. It is found in various 

 degrees of purity, but is in general one confused jumble, 

 and as hard rammed as if a giant had used one of the 

 Stacks of Duncansby as a paving hammer." 



STACKS OF DUNCANSBY. 



