CHAP. xii. GLACIAL ACTION. 163 



abundant, I know, in the British seas, but somehow, 

 owing to the set of the currents, they are never thrown 

 on Thurso shores." 



On the following evening, he again set out to ex- 

 amine the blue clay, and found a fine section at Thurdis- 

 toft. A large mass of clay and stones had fallen down 

 the bank The stones from the blue clay differed from 

 those of the red. He had before been at Weydale, up 

 the country, and at the quarries on the hill of Forss, to 

 detect glacial action on the surface of the rocks. In 

 both cases he failed. But here, among these fallen 

 stones, he for the first time detected signs of glacial 

 action in four separate instances. 



" I now," he says, " put off my shoes, and, despite the 

 ' water kelpies,' took the ford and pushed on to a fine 

 section on the east side. I again found shell fragments. 

 My pleasure was great. I pushed on, and next found 

 a very high section opposite the Bleachfield, on the east 

 side. I found shell fragments here too. My pleasure 

 was doubled and trebled. ... I was joined by two boys, 

 who thought it capital sport !" 



Dick continued to walk early in the morning and late 

 at night in search of his marine shells. One morning 

 he found an entirely whole valve of Venus casina. He 

 found at one place on the river-bank a black band or 

 belt running diagonally in a waving manner across the 

 boulder clay. Above it, the clay was reddish ; below, it 

 was blue. On taking part of the black belt into his 

 hand and rubbing it, it felt like fine clay and fine sand 

 intermixed. " Am I to infer," he said, " that the wavy 



