252 Proceedings of the Royal Physical Society. 



no doubt, due to the great faults by which it has probably 

 been thrown down below the plane of marine denudation. 

 The Culm, Middle and Upper Devonian beds on the up- 

 throw side, with an aggregate thickness of over 2500 ft., have 

 at places been completely removed, laying bare the lowest 

 part of the Devonian formation. 



The intrusive diabases of the Lower Harz may have been 

 connected with volcanic rocks interbedded with strata of 

 Middle or Upper Devonian age at many other places besides 

 Elbingerode. These would be also denuded away at this 

 period, the Elbingerode beds alone being left, their synclinal 

 position having helped to preserve them from subaerial erosion. 



6. Newer Pal.^ozoic Period. 



The later phases of the great Palaeozoic age were character- 

 ised by abundant volcanic action, accompanied by several 

 physical changes of great magnitude, not only on the Harz, 

 but over Britain and many other parts of Europe. 



During the earlier part of the Permian period there were 

 volcanos in both the Mansfeld and the Ufeld districts, from 

 which streams of basalt and showers of tuff were emitted. 

 The basalt eruptions ceased after a time at both places, and 

 the volcanic products were washed about by the waves and 

 rearranged along the sea floor, or were covered up by sedi- 

 mentary deposits. At Mansfeld there was not so much 

 volcanic action during the remainder of the Eothliegendes 

 period as at Ufeld, where great sheets of porphyrite were 

 poured forth, till they had reached a thickness of perhaps 

 1000 ft., and formed a bank extending upwards almost to 

 the base of the Zechstein series. 



A slight unconformability is sometimes found between the 

 Coal-measures and Permian group, but at many places in the 

 south-eastern parts of the Harz there is evidence of a marked 

 geological break between the Eothliegendes and Zechstein 

 formations. There is, at the Pfaffenthalskopf near Lauterberg, 

 a patch of Eothliegendes, lying on the Hercynian rocks at a 

 height of about 1600 ft., and consisting of red rocks inter- 

 bedded with some of the quartz-porphyry before alluded to. 

 At a lower part of the same area between the Pfaffenthals- 



