with pure physics, not only on account of my own incompetency to 

 do justice to them, but because I would suggest, that however cer- 

 tain geological phsenomena maybe eventually proved to be connected 

 with the question of the density of the earth, it is obvious that un- 

 equal simultaneous elevations and depressions over so small an area 

 as Scandinavia can scarcely be due to such a cause. After ably 

 treating this subject, and showing that gi'eat terrestrial movements 

 only can be admitted as explanatory of the facts observed, M. de 

 Beaumont refers to the works of Bi'itish geologists, and suggests, as 

 indeed Mr. Phillips has done*, that the parallel roads of Glen Roy 

 may, by accurate measurement, be proved not to be parallel ; and 

 he then goes on to show, that the lines of ancient sea-level of com- 

 paratively modern periods, have undergone broad undulations or 

 great ascending and descending movements over extensive areas. 



Let us see how these views are strictly applicable to our own 

 country. The occurrence of ancient beaches containing marine 

 shells of existing species at different levels above the sea has long 

 been observed by geologists in the British Isles. Terraces of gra- 

 vel have also been noted at various altitudes. In some instances 

 they have been referred to the formation of lakes, but in others they 

 have been compared to sea shingle ; in many cases also they have 

 been merged with diluvial deposits, and latterly an endeavour has 

 oeen made to explain some of them by the action of glaciers which 

 are supposed to have barred up former lakes. It may be that we 

 should not endeavour to refer the whole of these phaenomena to one 

 common origin; though most persons must admit that the mass of 

 recent evidence proves the greater number of the superficial de- 

 posits, to which allusion is now made, to have been formed be- 

 neath the sea. Wherever, indeed, these accumulations are found 

 to contain marine shells so imbedded in the sand or gravel as to 

 resemble sea bottoms, and no doubt can remain of their origin, 

 the only question is, why do we find these shells at such different 

 altitudes ? why are the same marine remains (appealing to British 

 examples) placed at the height of upwards of 1600 feet in North 

 Wales, and a few feet only above the sea in Devonshire and Corn- 

 wall, and at heights varying from 200 to 400 in the central counties ? 

 Most geologists have been satisfied to reply (and I am myself of the 

 number), that in these evidences they had distinct proofs, not that 

 the sea had stood at an indefinite number of levels, thereby making 

 a most broken and irregular outline ivithin the same period (a sup- 

 position apparently absurd), but that the bottom of the sea bad 

 undergone irregular oscillations, some points having been raised to 

 much greater heights than others. The examination of the moun- 

 tains of North Wales and the adjacent plains of Shropshire, for ex- 

 ample, could lead to no other inference ; there being in tracts ab- 

 solutely contiguous, a difference of not less than 1000 feet between 

 the level at which the same species of marine shells are now lying : 

 and as no other portion of England or South Wales offers a trace 



* See Penny Cyclopedia, Parallel roads. , 



