THE GLACIAL PERIOD. 197 



1832, however, Professor A. Bernhardi speculated on the pro- 

 bability that the polar ice had formerly invaded Germany, and 

 spread as far south as the most southerly limits reached by the 

 glacial deposits, which he recognised as nothing less than the 

 morainic detritus left behind it by the ancient mer de glace. 1 

 But this sagacious observer was nearly half-a-eentury before his 

 time, and it is no wonder that his work should have remained 

 buried in oblivion until it was recently unearthed by Professor 

 G. Berendt. Agassiz likewise has speculated about the possi- 

 bility of a mer de glace having overflowed Germany. He was 

 of opinion, indeed, that the British Islands, Sweden, Norway 

 and Eussia, Germany and France, the mountainous regions 

 of the Tyrol and Switzerland down to Italy, formed but one 

 ice-field, the southern limits of which remained yet to be de- 

 termined. My friend Dr. Croll in a sketch-map showing the 

 path of the ice-sheet in the area of the North Sea has also 

 indicated the Scandinavian ice as overflowing Germany farther 

 south than Berlin. 2 Indeed the probability that the glacial 

 detritus, so enormously developed in Northern Germany, is the 

 product of land-ice rather than the random droppings of ice- 

 bergs has often been suggested in conversation by glacialists in 

 this country, and I gave expression to these surmises in the 

 first edition of my Great Ice Age. 3 But detailed proofs could 

 not then be adduced in support of that view. Geologists had 

 completely forgotten Bernhardi's investigations, and those of 

 Sefstrom and Naumann had likewise been overlooked. I believe 

 it was generally understood, at least by British geologists, that 

 no glacial striae had up till a year or two ago been detected 

 anywhere in the low grounds of Northern Germany. Yet 

 Sefstrom, as early as 1836, mentions that Professor Bose had 

 informed him of the occurrence of a striated rock-surface in a 

 limestone-quarry at Biidersdorf to the east of Berlin. The 

 markings had been exposed upon the removal of some thickness 

 of undisturbed superficial soil, and seem greatly to have as- 



1 Leonhard and Bronn — Jahrbuch, 1832, p. 257. 

 2 Climate and Time, p. 449. 3 See pp. 390, 505. 



