B/OLOGY 

 UBRARY 



DESCRIPTIVE NOTES 



ON THE TOPOGRAPHY AND VEGETATION OF SOME LOCALITIES 



VISITED BY THE EXCURSION IN DENMARK ARRANGED FOR 



THE MEMBERS OF L'ASSOCIATION INTERNATIONALE DBS 



BOTANISTES, JUNE 22 nd -JULY 3 rd 1913. 



EDITED BY THE 



DANSK BOTANISK FORENING. 



A Geological Sketch of Denmark. 



Denmark is a young country. It is true that in the island of Born- 

 holm, Archean rocks and Cambro-silurian as well as Rhsetico-liassic 

 formations occur, but in the rest of Denmark the Senonian and Danian 

 stages of the Cretaceous system are the oldest known. A deposit of 

 chalk, hundreds of metres thick, supports the younger formations. It 

 lies directly under the drift in the most northern Jutland and in the 

 south-eastern parts of the Danish islands. In the rest of Denmark it 

 is overlaid by Danian limestones and Tertiary deposits. 



As a rule these formations occur in regular, horizontal layers, but 

 in the cliffs of M0en the strata of the chalk are inclined and bent, and 

 numerous displacements along vertical and sloping thrust-planes have 

 destroyed the original connection of the strata and pushed chalk-layers 

 over the till and interglacial sand which originally formed the sur- 

 face of the country, so that these young deposits now occur between 

 the chalk-layers; at such places brooks have eroded picturesque gullies. 



The Danish Tertiary deposits are clays and sands. In the vicinity 

 of Silkeborg especially, Miocene brown-coal is found. Where this is 

 closely examined, it is found to pass downwards into a freshwater-mud, 

 which proves that the brown-coal is autochtone and deposited in 

 freshwater-basins. Plant-fossils are found both in the brown-coal and 

 in the mud. The brown-coal hitherto found has not been valuable 

 enough to pay exploitation. 



Of the deposits of the Ice Age till (boulder <*lay) is the most impor- 

 tant. It forms the greater part of the surface of the islands and of the 



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