128 On Lines of Anc'ient Sea-Levels. 



geometrical admeasurement, and lias shewn that such lines, 

 when correctly examined, arc neither horizontal nor parallel, 

 so is it my duty, believing that many of the Scottish gravel ter- 

 races have been produced by similar agency, to incite my brother 

 geologists to apply the rigorous method of* examination of M. 

 Bravais, and thus to render this branch of our enquiries more 

 exact. I entertain, indeed, the most sanguine hope, that be- 

 fore another anniversary passes over, the Scottish phenomena 

 will be tested in a similar manner with those of Norway ; and, 

 that as the beds of marine shells in England and parts of 

 Scotland and Ireland so clearly bespeak great irregularities of 

 movement in the land, so we shall bo equally able to shew 

 that in the Highlands, lines of elevation acting from different 

 centres and with different degrees of intensity, have raised 

 former sea-bottoms to the different levels at which we now 

 find them, whether along shores or in the deep lateral depres- 

 sions by which Scotland is so fissured. Let the memoir of 

 M. Bravais therefore, with the admirable commentary of ?vl. 

 Elie de Beaumont, be the stimulus to those w^ho enter upon 

 this inquiry, which should not be limited to the parallel roads 

 of Glen Roy, but extended to the Western Islands and shores 

 of the lochs of Western Ross, among which I have a recollec- 

 tion of numerous shingle terraces, including that so well de- 

 scribed by Captain Vetch* ; and eastwards, to the great ac- 

 cumulations adverted to on the southern shores of the Moray 

 Frith, wdiich in their turn should be connected wdth the ele- 

 vated shelly beaches of Banffshire, first pointed out by Mr 

 Prestwitch.t 



In quitting the consideration of this very interesting topic, I 

 cannothowever occupy this Chair without saying, that although 

 British geologists have not yet employed the rigorous test ap- 

 I)lied by M. Bravais, there is no department of our science on 

 which their observations have thrown more light than that 

 which embraces the phenomena of ancient sea-beaches. 

 Reasoning backwards from existing causes and the facts of 

 yesterday, Mr Lyell has, by a well-digested set of observations, 

 led us to contemplate the very period w^lien the ocean was 



* Geol. Trans, vol. i. p. 416. 



t M. cle Beaumont make? full allusion to the British cases. 



