164 



The fris/i Naturalist. 



red ; further observation is needed before we can speak with 

 certainty as to the significance of these colour-changes. The 

 top of the boulder clay is here about twenty feet above the 

 stream, in which the bed-rock (Ordovician slate) is seen. 

 Over the boulder clay lie forty feet of boulder gravels, con- 

 taining well striated Carboniferous limestone boulders, the 

 striae running parallel with the long axis, in the manner 

 characteristic of boulders striated by glaciers. Beside a steep 

 path to a roadside cottage, a band of blue boulder clay, two 

 feet thick, containing well striated boulders of Carboniferous 



Fig. 2. 



BOULDER CLAY.^, 



