THICKNESS OF DEFORMED SECTIONS 



905 



Section Number 



Original length of tract, in 

 miles (o) 



Length after folding, in 

 miles (b) 



Mean elevation through fold- 

 ing, in miles (c) 



Deduced thickness of crustal 

 block, in miles (x) 



5b 



9-5 



4-75 

 5-75 

 571 



The formula for ascertaining (x) is x = 



be 

 a - b 



The following diagram, copied from Chamberlin, shows the 

 location of the sections, the extent of the folding- and the cal- 



B 



Fig. 250. Plot of the Tyrone-Harrisburg folded section, representing the 

 thickness of the deformed shell beneath each of the six blocks as 

 developed by Chamberlin's method of measurement. The lines 

 A-B and B-C are drawn through the middle points of the 

 bottom lines of each of these blocks, except section 2, the apex 

 block. The triangle G, B, F is drawn equal in area to the sum 

 of the triangles G, H, I and D. E, F. The whole deformed mass 

 appears, subject to the necessary limitations, to be the triangular 

 block A, B, C. (After R. D. Chamberlin.) 



culated thickness of the block affected. (Fig. 250.) It shows 

 strikingly the fact that, where the crust is folded intensely, the 

 thickness of the crust involved is least ; where folding is slight, it is 



