Changes in the Relative Level of Sea and Land. 313 



feet above its present level, to permit the rafts of ice to pass 

 over the lowest part of the barrier .... An iceberg start- 

 ing from the West or North Highlands, and floating in a sea 

 1500 or 2000 feet above the present level of the Atlantic, is an 

 agent perfectly capable of effecting the transportation of the 

 stone, and offers, I think, the only conceivable solution of the 

 difficulty .... When the sea stood, as it certainly once did stand, 

 1000 feet or more above its present level, a current would set 

 eastward through the gulf then occupying the low lands, of 

 which the estuaries of the Forth and Clyde form the extre- 

 mities." Speaking of an ancient beach 32 feet above the 

 present high water line on the shore of Gare Loch, he says, 

 " We may infer that, when the glacier occupied the valley of 

 Gare Loch, the sea stood higher than it does now by at least 30 

 feet, and probably a great deal more."* It is possible that 

 these may be mere inaccuracies of expression in describing 

 changes of relative level of sea and land ; but if they are so, 

 they ought to be guarded against, for they may be very easily 

 misapprehended ; and they tend to perpetuate an error that 

 leads to the most false reasoning on many changes on the 

 earth's surface. 



If the land of Norway had been immovable, if the sea had 

 fallen from a higher level, the lines of its former shores, as 

 it sank at intervals, would have been continuous and paral- 

 lel ; but the raised beaches are, within short distances, at 

 different elevations. Other observers had marked this ; but 

 it is to M. Bravais that we are indebted for the iirst exact 

 measurements of the relative positions of the successive ter- 

 races, and these have demonstrated that their parallelism is 

 only apparent. During his residence on the Alten Fiord, 

 near North Cape, he extended his levellings over a space of 

 from 9 to 10 myriametres, that is, from about 55 to %2 Eng- 

 lish miles ; and he ascertained, that the two great lines of 

 ancient level there, which are on a slope rising from the sea, 

 come nearer and nearer to each other as they approach the 

 present shore ; their greatest elevation is in the upper part 



* Jameson's Edin. Phil, Journal, Jan. 1846. 



