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XI. — A Letter to Charles Lyell, Esq., on some Changes of Level which 

 have taken place in Denmark during the present period. 



By GEORGE FORCHHAMMER, Phil. Doct., For. Mem. G.S. 



[Read May 31, 1837.] 



My Dear Sir, 



IHE great interest which you have taken in the geology of Denmark, and the 

 influence which you have exerted on the whole progress of geology, more especially 

 of that portion which relates to our knowledge of the newer formations, make me 

 wish to communicate, through you, some facts which appear to me worthy of 

 being known to a Society, which has so much promoted our science. 



You are satisfied that a great part of Sweden is rising, not uniformly, but in 

 a manner which generally decreases in amount from north to south on the 

 Swedish coast of the Bothnian Gulf*; and in your last anniversary speech you 

 have published some observations by Mr. Nilsson on the subsidence of Scania, 

 the southernmost part of Sweden f. Thus it appears to be proved, not only that 

 the elevation varies in different places, but that even a movement in an opposite 

 direction takes place in some parts of this extensive country. In corroboration of 

 these facts, I will only mention, that the island of Saltholra, situated in the Sound, 

 and opposite to Copenhagen, is mentioned in the records of the Chapter of 

 Roeskilde in the 13th century, on account of the income which the clergy derived 

 from it. At present the island is hardly five feet above the level of the Sound, 

 and it is almost every autumn overflowed by the sea, some artificial mounds 

 serving as places of safety for the cattle which in summer graze on the island. 

 Now it is evident, that if Saltholm has risen during the last 600 years, the move- 

 ment must have been at a much slower rate than even in the island of Bornholm, 

 which rises about one foot in a century ; and considering how small a portion of 

 Saltholm would be left if it now subsided only two feet, the island would hardly 

 have been worth the notice of the rich Chapter of Roeskilde ; we may therefore 

 fairly infer that Saltholm either has been stationary or may have subsided during 

 the last 600 years. 



* Phil. Trans. 1835. f Proceedings Geol. Soc, vol. ii. p. 506. 



