Geological Society. 471 



In attempting to account for the existence of large and shady- 

 forests on spots where the coasts are now entirely shorn of vegetation, 

 we must embrace in our consideration the similar phenomena which 

 are so numerous, as almost to form a submarine fringe around our 

 island j and from these we may conclude, that when the whole 

 country was densely clothed with wood, the forests might have ex- 

 tended their limits in full vigour to marine tracts, where single trees 

 will no longer flourish. 



You were last year made acquainted with the existence, at various 

 places, of accumulations of sand, gravel, and clay, containing existing 

 species of marine shells, placed at different heights above the sea; 

 and a subsequent Memoir of Mr. Trimmer on a part of the estuary 

 of the Mersey describes the presence of fragments of shells of existing 

 species, in a stratum of sandy clay, containing numerous erratic 

 pebbles, and a few boulders. 



Having myself traced beds with recent sea-shells at considerable 

 and various heights above the sea, both on our eastern and western 

 coasts, I am disposed to think that there is already sufficient evidence 

 of our shores having undergone elevation at periods comparatively 

 recent, however difficult it may be to explain all such superficial 

 accumulations upon a similar hypothesis. 



If the coasts exhibit testimonies of such elevations, the evidence is 

 corroborated when we follow the course of those indentations which 

 penetrate far within the interior of the island. In most of these 

 we perceive accumulations of shingle and sand on the sides of val- 

 leys, some of which, by the fine lamination of their beds, indicate 

 long-continued and tranquil formation ; others, by the shivered and 

 fragmentary condition of their contents, bespeak a more tumultuous 

 mode of aggregation : the latter, therefore, were probably coincident 

 with periods of elevation of the land, which throwing up the shores 

 of the island, have converted former estuaries into existing plains, 

 bounded by ancient shores of gravel, leaving the rivers to meander 

 between their widely separated banks. 



If such phenomena be still traceable within this island, where the 

 subterranean energies of nature are now, and have been for so long 

 a period quiescent, what amount of valuable instruction may we not 

 hereafter derive from the presence of good observers in those countries 

 where volcanos and earthquakes, with their accompanying elevations 

 and depressions, are in frequent activity ? You are already aware of 

 the important services of Mr. Lyell, and how effectually he has at- 

 tracted attention to this branch of inquiry. I would further remind 

 you of the discoveries of M. de Boblaye, who has placed the succes- 

 sive elevations of land in a remarkably clear light, by showing the 

 existence in the Morea of four or five distinct ranges of ancient sea 

 cliffs, marked at different levels in the limestone escarpments by litho- 

 domous perforations, lines of littoral and sea-worn caverns, and other 

 striking proofs of former tidal action. 



The description of a large granitic boulder, by Mr. Maxwell, 

 resting on the slaty shores of Appin, in Argyleshire, leads me to 

 observe, that the numerous detached masses of rock, foreign to the 



