342 FOLDINGS OF STRATA chap. xvii. 



glacial epoch more complete, I shall describe in this chapter 

 some other changes in physical geograph}-, and in the in- 

 ternal structure of the earth's crust, which have happened 

 in the post-pliocene period, because they differ in kind from 

 any jDreviously alluded to, and ai*e of a class which were 

 thought by the earlier geologists to belong exclusively to 

 epochs anterior to the origin of the existing fauna and flora. 

 Of this nature are those faults and violent local dislocations 

 of the rocks, and those sharp bendings and foldings of the 

 sti'ata, which we so often behold in mountain-chains, and 

 sometimes in low countries also, especially whei'e the rock- 

 formations are of ancient date. 



Post-glacial Dislocations and Foldings of cretaceous and drift 

 Strata in the Island of Mben, Denmark. 



A striking illustration of such convulsions of post-pliocene 

 date may be seen in the Danish island of Moen, which 

 is situated about fifty miles south of Copenhagen. The 

 island is about sixty miles in circumference, and consists of 

 white chalk, several hundred feet thick, overlaid by boulder- 

 clay and sand, or glacial drift which is made up of several 

 subdivisions, some unstratified and othei'S stratified, the whole 

 having a mean thickness of sixty feet, but sometimes attain- 

 ing nearly twice that thickness. In one of the oldest members 

 of the formation, fossil marine shells of existing species have 

 been found. 



Throughout the greater part of Moen, the strata of the 

 drift are undisturbed and horizontal, as are those of the 

 subjacent chalk; but on the northeastern coast thejMiave 

 been, throughout a certain area, bent, folded, and shifted, 

 together with the beds of the underl^-ing cretaceous forma- 

 tion. Within this area they have been even more deranged 

 t!ian is the Englifsh chalk with flints along the central axis 



