POSTGLACIAL, &>c, DEPOSITS OF CONTINENT. 465 



clays with their arctic fauna are overlaid directly with marine 

 deposits of postglacial age, which frequently cover a wide 

 extent of country. These consist principally of clay and beds 

 of shells, sand, and gravel, and they prove that in postglacial 

 times the southern parts of Norway and Sweden were submerged 

 to the exent of 350 feet at least. The depth of the submergence, 

 however, must have been actually more. Thus in Norway and 

 Sweden the highest shell-banks occur at a height of 150 feet 

 above the sea, to which we must add 90 feet or thereabout to 

 allow of sufficient depth of water for the shell-fish to live in, 

 since they could not have existed at the actual high-tide mark. 

 This will give us a former submergence of 240 feet. Postglacial 

 shelly clays, however, attain a greater elevation than is reached 

 by any of the shell-banks. Kjerulf states that clays with shells 

 reach a height in Norway of 250 to 380 feet, and he would 

 allow 20 or 30 fathoms for the depth of water in which those 

 clays accumulated, which would give a submergence of 370 to 

 560 feet. 1 This agrees sufficiently well with the conclusions 

 arrived at by the Swedish geologists, Professor Erdmann stating 

 that the Postglacial clays of Sweden reach a height of 200 or 

 300 feet, and perhaps more. The old shore -lines of the post- 

 glacial sea are frequently marked out by littoral accumulations 

 — by heaps of sand and gravel and shells, which begin at 150 

 feet and occur at many different levels down to some 50 feet 

 above the sea. 2 



It is remarkable that no direct passage can be traced from 

 the true glacial shell-beds into those of postglacial age. The 

 latter everywhere appear to rest unconformably upon the former. 

 We leave the glacial clays stocked with the remains of a strongly- 

 marked arctic fauna, and are confronted in the overlying post- 

 glacial beds by a fauna which is distinctly temperate, and 

 approaches in character to that which now occupies the adjacent 

 sea. We shall by and by endeavour to discover the meaning 

 of this apparently abrupt transition from arctic to temperate 



1 Udsigt over det sydlige Norges Geologi, p. 3, 

 2 Expose des Formations Quaternaires de la Suede, p. 91. 



2h 



