170 



PE0CEEDIKG9 OF THE GEOLOGICAL SOCIETY. [Jan. 11, 



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is met with only at very low altitudes 

 near the coast. It frequently alternates 

 with beds of fine sand, and sometimes 

 with gravel, and generally becomes more 

 stony and of coarser quality on the higher 

 ground. This may be seen along the line 

 of the Porth and Clyde Junction Railway 

 between Drymen "and Bucklyvie, where 

 I have found remains of marine shells. 

 The greatest height at which I have 

 met with these fossils is, in Aberdeen- 

 shire, 300 feet, in this instance in a 

 deep mass of stratified gravel forming 

 the crest of a low hill about five miles 

 from the sea. The top of this gTavel- 

 bed reaches about 360 feet higher. At 

 Gamrie, in Banffshire, the beds of sand 

 and clay containing Arctic shells (first 

 noticed by Mr, Prestwich) reach to very 

 nearly the same height, but the position 

 of the shells there is only about 150 feet. 

 These are the highest positions known 

 to me of marine fossils in the glacial 

 beds of the north of Scotland. In the 

 Clyde district, near Airdrie, they have 

 been found up to 350, and in one case 

 512 feet, which is the greatest elevation 

 yet reported from any part of Scotland. 

 These facts indicate a considerable de- 2 ^H 



pression of the land, which seems to 

 have extended over all North Britain, 

 even to the furthest extremity of the 

 island ; and these fossiHferoiis beds of 

 clay, sand, and gravel are proved to be 

 of later date than the scratching of 

 many of the rocks, and the deposition of 

 much boulder-earth, from the fact of 

 their being in many instances seen to 

 rest upon the irregular and hummocky 

 surface of the latter. This I have my- 

 self seen in the vicinity of Edinburgh, 

 in Fifeshire, Aberdeenshire, and also on' 

 the west coast. Dr. Fleming has like- 

 wise given some good illustrations of the 

 same in his ' Lithology of Edinburgh.' 



This submergence seems to have fol- 

 lowed very close upon the great glaci- ^ ^^ " 

 ation of the country, if, indeed, it was not to some extent contem- 

 poraneous with it. It may have been that after the land-ice had 

 reached its greatest development, a depression of the coast took 



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