256 Proceedings of the Boyal Physical Society. 



4. Inversion of Strata. — This is a most convincing piece of 

 evidence in favour of a powerful fault. A similar inversion 

 occurs along the fault which has tilted up the Edge Coals on 

 the west side of the Midlothian Coalfield. An effective 

 sketch of such an inversion is given in Geikie's " Text-book," 

 fig. 252.1 



5. Brine springs occurring at the edge of the Palaeozoic 

 rocks at Harzburg show that there is a fissure communicating 

 with the great salt bed known to exist below the Triassic 

 rocks of the plain. 



A similar fault appears to bound the northern edge of the 

 Kyffhauser. The gneiss on which the red Permian beds 

 forming the top of the hill are seen to rest has apparently 

 been brought up against the Zechstein and Trias in the way 

 indicated on the accompanying section (No. 2). Neither of 

 these faults seems to have been noticed by previous observers, 

 as no indication of their presence is given on any geological 

 map which I have seen. 



The great fault of the Harz appears to run out and dis- 

 appear towards Langelsheim on the west. The unconform- 

 ability of the Coal-measures and Permian beds upon the 

 upthrow side of the fault near Ballenstedt (shown on section 

 No. 1) resembles the unconformability of the Old Eed Sand- 

 stone on the northern side of the great Caledonian fault 

 between Crieff and Cortachy in Forfarshire. 



The horizontal platform of Devonian rocks on which the 

 newer Palaeozoic rocks at Ballenstedt rest is seen to be nearly 

 on a level with the flat lying Upper Cretaceous beds of the 

 adjoining plain. The amount of upthrow of the fault at this 

 locality is thus equal to the thickness of the border rocks 

 from the base of the Eothliegendes to the middle of the 

 Cretaceous series. The red Permian rocks of Mansfeld reach 

 at places a thickness of 3300 feet, but it is probable that 

 only a part of the series, which may be taken at 1000 

 feet, extended over this portion of the Lower Harz. The 

 thickness of the Secondary formations is variable, espe- 

 cially if the vast triassic salt deposits be taken into 

 account. It is 3000 or 4000 feet along the northern Harz 



^ See also A. Geikie's ** Field Geology," chap. x. 



