INTERGLACIAL EPOCHS. 287 



ficiently remarkable, and the general results obtained may be 

 thus briefly summed up : — 



1. Lowest Boulder-clay and associated sand and gravel. — 

 These are the accumulations of the first recognised glacial 

 epoch, during the climax of which the mer de glace advanced 

 to the foot of the Saxon uplands. 



2. Sand and gravel with freshwater shells, and clay with 

 marine shells. — The first ice-sheet had disappeared from Ger- 

 many and Denmark when these deposits were laid down. They 

 show us that a wide land-surface existed in Northern Germany, 

 the shores of which probably extended to the neighbourhood of 

 the Baltic in Prussia, where we find occasional freshwater-shells 

 in marine littoral deposits. Denmark at this time was under 

 water. 



3. Middle Boulder-clay. — This indicates the readvance of the 

 ice-sheet in the second glacial epoch. Again it extended as far 

 south as Saxony. 



4. Ossiferous and shelly sands of Bixdorf and Tempelhof and 

 marine teds of North Prussia. — Again the oner de glace had 

 vanished, and a wide expanse of land appeared in Germany, 

 over which the Pleistocene mammalia wandered. The presence 

 of Elephas antiquus and Rhinoceros leptorhinus, together with 

 the musk-sheep and the reindeer, betokens change of climate. 

 The two pachyderms must have lived in Germany when the 

 climate of the interglacial epoch had become mild and genial, 

 and the latter when it was colder. The musk-sheep and its con- 

 gener might thus have entered the country either during the 

 disappearance of the second mer de glace, or shortly before the 

 advent of the last. The sand of Gerdauen, with its sea-shells of 

 arctic type, which occurs upon this geological horizon, shows us 

 that towards the close of the second interglacial epoch a some- 

 what cold sea overflowed the low-lying regions of North Prussia. 



5. Upper Boulder-clay. — For the last time the great Scan- 

 dinavian mer de glace occupied the basin of the Baltic, overflowed 

 Denmark and Holstein, and advanced as far south at least as 

 Berlin. 



