8 Review of Chambers- s Ancient Sea Margins, 



Adjoining Glen Hoy lies Glen Gluoy, which opens below upon 

 Loch Lochy. This valley has two distinct shelves or terraces, 

 one 1159 feet above high tide, and the other 959-969 feet. Other 

 shelves occur in Glen Spean, as well as in Glen Roy, whose 

 heights are mentioned in the table on page 6. The whole 



system has afforded a fruitful, and most interesting subject of 



speculation. The " perfect horizontally" of the terraces, (their 

 height above the present bottom of the valley therefore diminish- 

 ing upward, instead of rising with the valley,) their extent, and 

 the character of the region around, are the basis of the two views 

 recently urged, the one attributing them to inland lakes, the other 

 regarding them as beaches of an arm of the sea. 



Mr. Chambers adopts the latter view : and as he discusses the 

 character of the other terraces of Scotland and England, he ar- 

 rives at the same conclusion for them all. He finds the same 

 "ancient sea-margins" in foreign regions. In France and North 

 America he seems to detect terraces of equivalent height with 

 those of Scotland, and all are set down as marking former levels 

 of the sea. A natural terrace and a sea-beach are therefore in 

 his view nearly synonymous terms. 



We do not pretend to deny, without examination, the conclu- 

 sion in particular cases carefully studied by Mr. Chambers. But 

 the sweeping deduction needs much, very much, restriction. 

 And even many of his own examples demand better proof of the 

 former presence of the sea than has been presented. 



The principle that ' what has been, may again be, and the re- 

 verse,' is acknowledged to be a safe test of truth in geology. If 

 the last elevation of sixty feet (or thirty if it be so) which Scot- 

 land has experienced, produced elevated sea-beaches, and no 

 proper river terraces, — if all the existing river terraces are remains 

 of other sea-beaches and proofs of other higher elevations, — then 

 another elevation of sixty feet would produce a similar result, 

 and this alone. In order to ascertain the truth, the necessary 

 effects of such a change of level may be briefly reviewed. These 

 effects are as follows : 



1. The formation of elevated beaches on many parts of the 

 sea-coast about sixty feet above the sea, varying in height some- 

 what as actual sea-shores vary, according to their position with 

 reference to the winds and tides. 



2. The beds of rivers being raised, as well as the rest of the 

 land, the amount of descent to the sea would be increased ; and 

 in consequence of this, their waters would run more violently, 

 the excavating force would be augmented, and they would go 

 on with a process of rapid degradation, until the former rate 





