to the Parallel Roads of Lochaher. 37 



while further back the detritus only shows itself in terraces, 

 formed by the streams cutting into the talus at the base of the 

 high mountains. 



Mr. Chambers regards the question of the origin of the 

 Parallel Roads as " involved in that of the superficial forma- 

 tions generally, which bear the marks of former levels of the 

 sea at various intervals up to 1200 feet;" the various mark- 

 ings in the three kingdoms, in France, &c, " all falling into 

 such conformity as to prove that the shift of level has been 

 effected from at least that height with perfect equability 

 throughout." He considers this widely extended and strongly 

 marked conformity "as more favourable to the idea of a re- 

 cession of the sea as opposed to that of an elevation of the 

 land, since it is precisely what would result from the former 

 operation, while there is an obvious difficulty in supposing" 

 that so large a portion of the earth's crust could be repeatedly 

 upheaved, and yet the relative levels so preserved " that be- 

 tween Paris and Inverness not a vertical foot of derangement 

 could be detected." 



The explanation of the origin of the Parallel Roads is thus 

 mixed up with, indeed forms an essential part of, his general 

 theory. And whatever difficulty geologists may feel in giving 

 their assent to such generalizations as those just quoted, or how- 

 ever unwilling they may be, in the present state of inquiry, to 

 admit many successive equable sinkings of the waters of the 

 ocean all over the globe, the same difficulties and hesitation must 

 be experienced in receiving Mr. Chambers's explanation as the 

 true theory of the Parallel Roads. Resides, the speciality of 

 the phaenomena is by no means accounted for on this hypo- 

 thesis. It appears to me to require a special local cause. 

 On the hypothesis of the shelves being formed by the sea, it 

 cannot, I think, be shown why other Highland glens were not 

 equally impressed ; or that any conservative influences have 

 operated in Lochaber, which were not just as likely to prevail 

 in other places. This argument cannot be properly estimated 

 by one who has not seen the shelves in Glen Roy and Glen 

 Gluoy ; from examining sea and lake-terraces, from descrip- 

 tions and drawings, the faintest conceptions only can be formed 

 of the wonderful reality. Any one on whose view the scene 

 which is presented on turning the flank of Bohuntine hill 5 

 bursts for the first time, must look with the deepest astonish- 

 ment at the distinctness, continuity, and extent of the shelves ; 

 he will feel how inadequate were all his conceptions, and 

 how little the Parallel Roads have in common with any appear- 

 ances which have come under his notice before. Mr. Cham- 

 bers eloquently describes the first impressions, and acknow- 



