Professor G. Forchhammer on the Downs of Denmark. 71 



the course of time, this canal should become again obstructed, 

 and the streams of the former sound again filled with fresh 

 water, fresh-water fishes and shells would again make their 

 appearance ; and thus a frequently repeated alternation of the 

 organic remains of the inhabitants of the sea and of lakes 

 would be produced. Although this change is of very great 

 moment to the inhabitants of the districts near the Liimfjord, 

 inasmuch as the irruption of the sea, by destroying the fisher- 

 ies, annihilated the means of support of the inhabitants, while, 

 on the other hand, by the free communication with the North 

 Sea, it opened up new paths of commerce and navigation ; 

 yet the alteration of surface is comparatively trifling, whereas 

 the formations at the bottom of this sea have entirely altered 

 their character. 



Between the ranges of downs, there frequently occur land 

 lakes, of greater or smaller extent, which are termed Down- 

 lakes ; and in these, a strong vegetation of marsh plants is 

 combined with the formation of peat {Torf-Bildung), which, so 

 long as the down-sand is kept under, quietly progresses. 

 When, however, an unusually strong storm acts on the diffi- 

 cultly repressed downs, then the sand flies into the lakes, covers 

 the peat with layers of sand, and puts an end to that forma- 

 tion. When afterwards, in the course of time, the currents 

 of the sea cut away the coast, the downs retire into the land, 

 fill up the lakes, and form in this manner those remarkable 

 beds of fossil peat termed Martorv, which seem to have re- 

 mained unknown to the geologists of the rest of Europe. To 

 the north of the village of Ageren, there are a great many of 

 these beds of Martorv ; but the most extensive is the most 

 northern of all, which, in the communes of Raabjerg and Ska- 

 gen, on the west coast, has an extent of five English miles, 

 and stretches deep into the land. But this interesting pheno- 

 menon is not confined to this coast. On the north coast of 

 Seeland, in the last century, there was a very destructive 

 tract of drift-sand, which, however, in the year 1760, was 

 repressed, and is now covered with fir-woods. The drift-sand 

 has half covered some peat-moors which lie at the boundary 

 of the chain of downs, and thus partially interrupted the growth 

 of the peat. Now, while the still living moor, if I may be al- 



