Geology of the Harz Mountains. 229 



spores. In the Dorothea Mine at Clausthal, an ancient level 

 was opened some years ago, in which the pine timbering, 

 which had been imprisoned for about 400 years, was found 

 converted into true brown coal, specimens of which may be 

 seen in the Oberbergamts Museum there. The case is inter- 

 esting, as it proves that under requisite conditions of pressure, 

 warmth, and moisture, brown coal may be formed at a com- 

 paratively rapid rate. 



k. Drift and Loss. 



The Oligocene beds are covered by great sheets of drift 

 (Diluvium) which extends over immense areas in the north 

 of Germany, and consists of clays, sands, and gravels, of 

 local or Scandinavian origin. 



Erratics are abundant in the diluvium, and are found scat- 

 tered over the western part of the Lower Harz, along with 

 the so-called " Brown Coal Quartzite " pebbles. They have 

 not been found on the eastern Harz ; and the bounding line 

 which crosses the range between Stolberg and Gernrode is 

 taken as the western limit of the Great European ice cap 

 during the period of maximum glaciation.^ 



Traces of glaciers are said to have been found in some of 

 the valleys of the Harz.^ Moraines have been described as 

 occurring in the Oderthal, a deep glen which rises in 

 the plateau between the Bruchberg and the Brocken at 

 a height of 2500 ft,, and runs southwards past Andreasberg 

 to the border of the district at Lauterberg. The moraines 

 are, however, far from distinct, and may ultimately turn 

 out to be portions of old river terraces rounded off by 

 subaerial erosion. 



The much debated Loss occurs along the south-eastern 

 flanks of the Harz near Nordhausen and on the Kyffhauser 

 near Kelbra. It is regarded by Dr J. Geikie as the flood 

 loam laid down by the vast inundations that took place 

 during the melting of the great glaciers.^ The " ^olian 



1 See map of the Ice Sheet appended to Professor J. Geikie's recent Work, 

 *' Prehistoric Europe." 



2 E. Kayser, Verhandl. d. Gesellsch. f. Erdkunde Zu Berlin, 3 Decemb. 

 1881 ; also K. A. Lossen, Zeit. d. d. geol. Ges., xxxiii., 1881, p. 708. 



2 Great Ice Age, 2d edit., p. 550. 



