RAMBLES OF A GEOLOGIST. 309 



to the Ord Hill of Caithness, I had never found in the boul- 

 der-clay the slightest trace of an organism that could be held 

 to belong to itself ; and as it seems natural to build on nega- 

 tive evidence, if very extensive, considerably more than mere 

 negative evidence, whatever the circumstances, will carry, I 

 became somewhat sceptical regarding the very existence of 

 boulder-fossils, a scepticism which the worse than doubtful 

 character of several supposed discoveries in the deposit served 

 considerably to strengthen. The clay forms, when cut by a 

 water-course, or assailed on the coast by some unusually high 

 tide, a perpendicular precipice, which in the course of years 

 slopes into a talus ; and as it exhibits in most instances no 

 marks of stratification, the clay of the talus a mere re-for- 

 mation of fragments detached by the frosts and rains from 

 the exposed frontage can rarely be distinguished from that 

 of the original deposit Now, in these consolidated slopes it 

 is not unusual to find remains, animal and vegetable, of no 

 very remote antiquity. I have seen a human skull dug out of 

 the reclining base of a clay-bank once a precipice, fully six 

 feet from under the surface. It might have been deemed the 

 kull of some long-lived contemporary of Enoch, one of the 

 accursed race, mayhap, 



" Who sinned and died before the avenging flood." 

 But, alas ! the labourer dug a little farther, and struck his 

 pickaxe against an old rybat that lay deeper still. There 

 could be no mistaking the character of the champfered edge, 

 that still bore the marks of the tool, nor that of the square 

 perforation for the lock-bolt; and a rising theory, that would 

 have referred the boulder-clay to a period in which the polar 

 ice, set loose by the waters of the Noachian deluge, came 

 floating southwards over the foundered land, straightway 

 stumbled against it, and felL Both rybat and skull had come 

 from an ancient burying-ground, that occupies a projecting 

 angle of the table-land above. I must now state, however, 



