INTERGLACIAL EPOCHS. 285 



sheet, as Johnstrup maintains, appears to be clearly made out. 

 The succession of changes evinced by the drift-deposits of Moen, 

 as given by Dr. Penck, is extremely interesting. After the ice 

 of the first glacial epoch had melted away, the Cretaceous strata 

 of Moen lay undisturbed, and covered with a sheet of boulder- 

 clay. At this time a shallow sea overspread this part of 

 Denmark, and sand with molluscan remains gradually gathered 

 over the surface of the old bottom-moraine. Then ensued the 

 second glacial epoch, when glaciers began to descend to the 

 Baltic, the bottom of which became cloaked with the fine mud 

 carried down by sub-glacial waters. Thereafter the ice gradually 

 advanced, rolling up this mud with its bottom-moraine, and 

 overflowing the Danish country as before. The Cretaceous 

 deposits of Moen being thickly covered by older drifts, were to 

 some extent protected from the grind of this second ice-sheet, 

 as is shown by the fact that the second boulder-clay contains no 

 chalk fragments until we pass westwards of Moen. After the 

 disappearance of this second ice-sheet Moen and the rest of 

 Denmark appeared as a low flat land, which in the course of 

 time was deeply incised by streams and rivers, and eroded by 

 the waves and breakers until it came to present lofty cliffs to 

 the sea, like those which are now to be seen at Stevens Klint. 

 When the ice of the last glacial epoch next advanced upon 

 Denmark, its passage was thus opposed by long precipitous 

 walls of chalk, against which it pressed with enormous force, 

 rupturing and smashing the rock, dragging huge masses of it 

 out of place, squeezing tongues of boulder-clay into the fissures ; 

 and in short producing all the wild confusion and disturbance 

 which is now so conspicuous a feature at Moens Klint. 



The drift-deposits of Faxoe offer a similar succession of 

 boulder- clays, and, like those of Moen, betoken three glacial 

 epochs separated by interglacial eras of milder climatic condi- 

 tions ; and precisely the same results have been obtained by a 

 study of the glacial phenomena in Southern Sweden. 



The youngest of all the glacial deposits are those enormous 

 erratic blocks and boulders, and wide-spread sheets, hummocks, 



