470 SCIENCE PROGRESS. 



having taken place in the region without the production of 

 faulting. (It may be here pointed out that Dr. Rothpletz 

 argues that the Linththal is the result of a broad mountain 

 region being faulted down between two parallel fault planes, 

 whereas Heim holds that all the principal valleys are the 

 result of continuous erosion acting through long periods.) 

 The peculiar folding of the rock-mass, which has been 

 pushed forward from the north, and cut off by the thrust 

 plane, is inconsistent with the conception of a squeezed out 

 middle limb (Ost. A /pen, p. 256). What, then, are the 

 great principles which underlie this attack upon an ap- 

 parently well-established theory ? Folding, as the great 

 basis of mountain building, remains unaffected, but that 



isr 



a. 



B- 



^£2??5E7yS252s 



Fig. 3. — Illustrating Rothpletz's interpretation of the Doppelfalte. 



A the Jurassic, and B the Verrucano members of the broken folds pushed along 

 the overthrust plane, which is here represented by a dark line. 



C. Eocene trough, contorted as in previous figure. (The curves have been 

 simplified in the drawing.) 



D. Jurassic member of the inclined trough. 



E. Verrucano member of the inclined trough. 



overthrusting is synonymous with overfolding is strenu- 

 ously denied. The leaders of the New Geology have 

 hitherto, to a large extent, held that folding and overthrust 

 stand in the closest connection, whereas Rothpletz main- 

 tains that folding has preceded the overthrust, the latter 

 frequently cutting right across the folds. 



On the other hand our author considers that a close 

 relationship exists between overthrusts and faults, and en- 

 deavours to show that where the former are scarce, normal 

 faulting takes their place. 



The points in Heim's theory that he specially attacks 

 are : (1) The overfolding with squeezing out of the middle 

 limb ; (2) the conception of latent plasticity ; (3) rock meta- 



