312 RAMBLES OF A GEOLOGIST. 



carefully or more perseveringly than he, or who can enjoy 

 with higher relish the sweets of scientific research. I wrote 

 him regarding Professor Forbes's decision on the boulder-clay 

 of Wick and its shells ; urging him to ascertain whether the 

 boulder-clay of Thurso had not its shells also. And almost 

 by return of post I received from him, in reply, a little packet 

 of comminuted shells, dug out of a deposit of the boulder- 

 clay, laid open by the river Thorsa, a full mile from the sea, 

 and from eighty to a hundred feet over its level. He had 

 detected minute fragments of shell in the clay about a twelve- 

 month before ; but a scepticism somewhat similar to my own, 

 added to the dread of being deceived by mere surface shells, 

 recently derived from the shore in the character of shell-sand, 

 or of the edible species carried inland for food, and then trans- 

 ferred from the ash-pit to the fields, had not only prevented 

 him from following up the discovery, but even from thinking 

 of it as such. But he eagerly followed it up now, by visit- 

 ing every bank of the boulder-clay in his locality within 

 twenty miles of Thurso, and found them all charged, from 

 top to bottom, with comminuted shells, however great their 

 distance from the sea, or their elevation over it. The frag- 

 ments lie thick along the course of the Thorsa, where the en- 

 croaching stream is scooping out the clay for the first time 

 since its deposition, and laying bare the scratched and fur- 

 rowed pebbles. They occur, too, in the depths of solitary 

 ravines far amid the moors, and underlie heath, and moss, 

 and vegetable mould, on the exposed hill-sides. The farm- 

 house of Dalemore, twelve miles from Thurso as the crow 

 flies, and rather more than thirteen miles from Wick, occu- 

 pies, as nearly as may be, the centre of the county ; and yet 

 there, as on the sea-shore, the boulder-clay is charged with 

 its fragments of marine shells. Though so barren elsewhere 

 on the east coast of Scotland, the clay is everywhere in Caith- 

 ness a shell-bearing deposit ; and no sooner had Mr Dick de- 



