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ther with fragments of secondary rocks with their characteristic 

 fossils from the mountain limestone to the chalk inclusive. Mr. 

 Spencer supposes that the current which brought these materials 

 into their present situation must have flowed from the north. The 

 diluvium here alluded to seems to correspond to that which covers 

 the crag of Norfolk, and which is in some places intimately con- 

 nected with that deposit. I may add that I have seen a similar for- 

 mation on the banks of the Elbe, below Hamburgh, and in other 

 parts of Denmark, with erratic blocks included in it in some 

 places. 



Our Secretary, Mr. Hamilton, has described a bed of marine 

 shells, of recent species, on the southern coast of Fifeshire, near 

 Elie, part of the deposit being twelve or fourteen feet above the 

 level of high tide. Similar marine shells have been observed above 

 the sea-level in many of the lowlands bordering the estuaries of the 

 Forth and Tay ; and in the memoirs before mentioned Mr. Murchi- 

 son has described a raised beach at the mouth of Carlingford Bay, 

 Ireland, which he lately examined in company with Professor Sedg- 

 wick. Mr. De la Beche also informs us that he has lately disco- 

 vered proofs of two movements of the land of Somerset, DevoUj and 

 Cornwall, one to a height of about thirty to forty feet above the 

 present sea-level, and another to an uncertain depth beneath it, 

 both subsequent to the period when the vegetation of the land and 

 the molluscous inhabitants of the neighbouring sea were the same 

 as they now are. 



The evidence, therefore, is annually augmenting in favour of con- 

 siderable alterations in the relative level of land and sea having been 

 brought about in northern Europe at a comparatively modern epoch. 

 For this reason I am more than ever disposed to refer to great move- 

 ments of elevation and depression, the origin and present position of 

 the loess of the valley of the Rhine, of which I gave some account 

 in a former year. I have lately had occasion to recall your atten- 

 tion to this ancient silt in which terrestrial and aquatic shells are 

 preserved of species still living in Europe. It is found from below 

 Cologne to the neighbourhood of the Falls of Schaffhausen, exhibit- 

 ing almost everywhere the same mineralogical character and fossils, 

 forming sometimes low hills which cover the gravel of the great al- 

 luvial plain of the Rhine, sometimes rising up on the flanks of the 

 mountains which border the great valley to an elevation of 300 or 

 400 feet above the river, or more than 1200 feet above the sea. I 

 discovered lately, in the neighbourhood of Basle, the first remains 

 of fossil fish which have been detected in this silt ; and Mr. Agassiz 

 recognized them as the vertebrae of a small species of the Shark fa- 

 mily, perhaps of the genus Lamna. They were associated with the 

 usual fresh-water and terrestrial shells, and the fact appeared ano- 

 malous, but the celebrated ichthyologist informs me that species of 

 this family and of the Skate tribe have been known to ascend from 

 the sea up the mouths of the rivers Senegal and Amazon to the di- 

 stance of several hundred miles. 



Some have imagined that a great lake once extended throughout 



2 B 2 



