GERARD DE GEER QUATERNARY CHANGES OF LEVEL. 05 



The third paper read was — 



QUATERNARY CHANGES OF LEVEL IN SCANDINAVIA. 

 BY BARON GERARD DE GEER, OF THE GEOLOGICAL SURVEY OP SWEEDEN, STOCKHOLM. 



Although I have not had sufficient time to prepare an elaborate lecture, I have 

 thought it appropriate on the present occasion to place briefly before the Geological 

 Society of America a synopsis of our present knowledge in regard to the Quaternary 

 changes of level in Scandinavia, inasmuch as there are yet prominent geologists 

 who deny the existence of continental upheaval. The conditions found in Scandin- 

 avia, however, seem to afford good evidence of such changes. Moreover, this 

 seems to be the very time to place before you for comparison the analogous phe- 

 nomena in northern Europe, since so extensive and excellent investigations in 

 relation to Quaternary changes of level in North America are in progress just 

 now. And finally, it was my good fortune, immediately before leaving Sweden, to 

 complete my observations in such a way that it has been possible to give a general 

 view of the question and to present a somewhat detailed ,map of the changes, so far 

 as southern Sweden is concerned. 



It has been long known that raised marine deposits with an arctic fauna occur 

 over the latest moraines in Scandinavia, and in most text-books they are said to be 

 found as high as 500 feet in Sweden and 600 feet in Norway ; but exact determina- 

 tions of the uppermost marine boundary itself have not been given, thereby allow- 

 ing too much latitude for speculation in regard to the cause of the present high 

 altitudes of these deposits. It is true that the eminent French physicist, Bravais, 

 half a century ago came to the conclusion that two elevated rock-terraces in north- 

 ern Norway examined by him are not horizontal but descend toward the north, the 

 upper one more so than the lower ; but his opinions have been doubted more and 

 more, and several geologists, even from Scandinavia, are less inclined to believe in 

 an unequal upheaval of the earth's solid crust than in changes of the level of the 

 changeable sea. 



In Sweden no such rock-terraces as those of Norway, which are visible for miles 

 and miles, are found, nor are there, as a rule, long, continuous beaches; for the 

 wooded country is very hilly, so that it is not easy to connect the beaches and find 

 out whether tin- changes have been unequal or not. It seemed probable, however, 

 that the upper boundary of the marine deposits might be synchronous at the dif- 

 ferent localities, and I have, therefore, since 1883, attempted to determine altitudes 

 as often as an opportunity was offered. This assumption I have recently been able 

 to substantiate by the observation that the maximum of depression did not occur 

 quite simultaneously with the ice-covering, but somewhat later, as shown by chan- 

 nels cut through the summits of terminal moraines by glacier rivers coming down 

 from the ice-border at about '.)."> per cent of the height of the upper marine bound- 

 ary. Hitherto I have seen such channels of erosion only about the northernmost 

 extension of the terminal moraines on the map, just in the vicinity of the Norwegian 

 frontier; but it is probable thai they occur in many other places, and, if so, it will 

 be possible more accurately to determine the level of the sea at the margin of the 

 receding land-ice. At present it is already evident that at the maximum depression 

 no ice could, at least in southern Sweden, obstruct the synchronous formation at 

 all points of the uppermost beach. 



IX— Bull. Geol. Soc. Am.,.Yol. :i, 1891. 



