472 SCIENCE PROGRESS. 



ing the amount of strata which would have to be affected by 

 it). In addition the beds both above and below the thrust 

 plane dip at a higher angle than the latter, and nowhere 

 along the surface does any evidence exist of a squeezed out 

 middle limb. 



To account for these conditions our author again refers 

 to Daubre.e's experiment (fig. 3, and Geo- Tecktonische Pro- 

 bleme, fig. 41), submitting that instead of these great inver- 

 sions originating under deep-seated conditions, they have 

 in reality been formed in that part of the earth's mass no 

 longer subject to continued compression. The occurrence 

 of overthrusting only to the north of the Juras is accounted 

 for, if these mountains be included as forming part of the 

 Alpine system, seeing that the whole movement lies in the 

 northern direction of the northern side of the main mountain 

 axis, though exceptional conditions may arise, such as the 

 southern overthrust in the Glarner Alps. 



As additional evidence in support of his theory Roth- 

 pletz cites the Scotch area, and quotes from the Report of the 

 Scotch Geological Survey, p. 411. 



" There are two points, however, in the former official 

 report, which, in the light of recent evidence, require modi- 

 fication. First, it was stated that during the incipient stages 

 of the movements the strata were thrown into folds, which 

 became steeper along the western front till they were dis- 

 rupted, and the eastern limb pushed westward. The folds 

 were believed to have culminated in reversed faults ; but 

 it is apparent that the latter need not necessarily be preceded 

 by folding." 



It is a remarkable fact with regard to Scottish thrust 

 planes that not a single case of inversion of strata seems 

 to be known, rendering, therefore, almost impossible any 

 connection with original overfolding, and the suggestion is 

 hazarded that lateral pressure having been active, the 

 elevated mountain area has been thrust over a lower-lying 

 plateau which occupied the region now hidden beneath the 

 sea between the mainland and the Hebrides. 



The Lausitz (Saxony), Westphalian, and Belgian areas 

 are next considered, and although in the latter the results 



