286 Prof. Sedgwick and Mr. Murchison on the Raised Beach, 5fc. 



to the highest navigable points in Shropshire, we find (as has been shown by 

 one of the authors*) that gravel and sand, with sea-shells of existing species, 

 occur in many places, at elevations of from 300 to 600 feet above the sea : and 

 still further to the north, the elevation of similar deposits is maintained 

 through Lancashire, till they approach the mountains constituting the southern 

 fringe of the Cumbrian chain. Hence we have no hesitation in admitting^ 

 that in a portion of our island which ranges from Cornwall and Devon to the 

 southern limits of the Cumbrian chain, there have been great movements of 

 elevation subsequent to the creation of existing mollusca ; these movements 

 apparently increasing in intensity as we proceed from south to north, or rather 

 from south-west to north-east. 



No doubt there are many portions of the coast of our island, where we not 

 merely have no proofs of any change in the relative level of land and sea, 

 produced by elevation during the modern period, but where we appear to have 

 direct evidence of a partial depression of the land. It is not, however, our in- 

 tention to enter any further on these subjects. We have described a local phe- 

 nomenon of some interest, and endeavoured to show its connexion with similar 

 phenomena on a more extended scale. But any consideration of the effects 

 produced by such movements as we have described, on the general configura- 

 tion of our island, or on the drifted materials which are accumulated on its sur- 

 face, would lead us into details quite beyond the purpose of this short memoir. 



* Proceedings Geol. Soc, vol. ii. p. 335. 



Sectional view of the Raised Beach.— a, Sand Banks. b. Raised Beach. d. Silurian Rock. 



