steuart's planter's guide. 291 



downs. There are some former islands which have 

 been altogether shorn down to this sea-level, of 

 which the Bell-Rock, extending nearly a mile of 

 shelf, affords a well known specimen. In many places 

 of the coast, these shelves accord with the superior 

 former level of the sea, and with the floors of the 

 caves. 



In proof of the sea having advanced upon the 

 land, there are vestiges of submerged forests (the 

 stumps of the trees standing erect where they grew, 

 at or a little above the present lowest ebb) existing 

 at different places on the eastern coast, both of 

 England and Scotland, and these vestiges standing 

 upon a former carse or alluvium of the rivers, are 

 visible in the same firths with the upper level of carse, 

 of course generally more to seaward than these higher 

 carses, as deposition of rivers occurs at what may be 

 termed deposition point, that is where the rivers, 

 from the stemming of the sea-water, begin to widen 

 — where the firths commence ; and the slowness of 

 the motion of the water gives time for the subsi- 

 dence of the floated mud. By reason of the flux 

 and reflux of the tide into the mouths of rivers, this 

 deposition takes place only at or near high water, 

 that is, when the strength of the inward tide-flux 

 ceases, and before that of the reflux begins. It is 



T 2 



