CHAP. xm. ERRATICS OF RECENT PERIOD IN SWEDEN. 239 



birch. Lastly, under the influence of the Grulf Stream, and 

 various changes in the height and extent of land in the arctic 

 circle, a melting of nearly all the permanent ice between lati 

 tudes 60 and 70 north, corresponding to the parallels of the 

 continental ice of Greenland, has occurred, so that we have now 

 to go farther north than lat. 70 before we encounter any 

 glacier coming down to the sea coast. Among other signs of 

 the last retreat of the extinct glaciers, Kjerulf and other 

 authors describe large transverse moraines left in many of the 

 Norwegian and Swedish glens. 



Chronological Relations of the Human and Glacial 

 Periods in Sweden. 



We may now consider whether any, and what part, of these 

 changes in Scandinavia may have been witnessed by man. 

 In Sweden, in the immediate neighbourhood of Upsala, I 

 observed, in 1834, a ridge of stratified sand and gravel, in 

 the midst of which occurs a layer of marl, evidently formed 

 originally at the bottom of the Baltic, by the slow growth of 

 the mussel, cockle, and other marine shells of living species 

 intermixed with some proper to fresh water. The marine 

 shells are all of dwarfish size, like those now inhabiting the 

 brackish waters of the Baltic ; and the marl, in which myriads 

 of them are imbedded, is now raised more than a hundred 

 feet above the level of the Grulf of Bothnia. Upon the top 

 of this ridge (one of those called osars in Sweden) repose 

 several huge erratics, consisting of gneiss for the most part 

 unrounded, from nine to sixteen feet in diameter, and which 

 must have been brought into their present position since the 

 time when the neighbouring gulf was already characterised 

 by its peculiar fauna. Here, therefore, we have proof that 

 the transport of erratics continued to take place, not merely 

 when the sea was inhabited by the existing testacea, but 



