352 



DYNAMICAL GEOLOGY. 



erally, or in the direction of the width and length of the block ; and this 

 lateral movement or flow had bulged the sides much more at bottom than 



at top, and most about the middle. At 



322. 



bottom the block was increased -^-^ in 

 width and -^ in length. 



Punch at a depth of IJ inches. 

 323. 



The block had 

 been made of plates of iron welded to- 

 gether, and these were bent downward 

 as the punch passed in, the lower ones 

 the least ; and Fig. 322 shows the ap- 

 pearance of the surface, after polishing 

 and etching with acids, of a section 

 through the middle, when the punch 

 had entered 1\ inches, and the core pro- 

 jected an eighth of an inch. 



Such facts, together with those re- 

 lating to the heat developed by friction, 

 take the mystery out of the process of 

 flexing rocks. 



3 Fractures and displacements under 

 pressure. — The production of fractures 

 through lateral pressure has been experi- 

 mentally illustrated by Daubree. In one 

 of his experiments he used an oblong 

 square prism consisting of layers of 

 beeswax, and applied the force at the 

 middle of the two ends after protecting 

 them by small blocks or plates of the same cross-section. Fig. 324 repre- 

 sents, half the natural size, the prism ready for the experiment. One of 

 the results, after applying the pressure, is shown in Fig. 325 ; and another, 

 after using a stronger pressure, in Fig. 326. 



In both, a flexure becomes the course of a fracture, and also of a fault; 

 and in 326 it is shown that the flexure-fault is not at the axis of the flexure, 

 but beyond it, between the anticline and syncline. In Fig. 327 are shown 



324. 



Core out. Townsend. 



Prism made of layers of wax of different colors, (x J.) Daubree. 



two oblique fractures and faults, obtained in another trial. The fractures 

 have their planes parallel as well as very oblique; and the faults were made 

 by a shove up along the oblique surface. So the greater fractures of 

 mountain regions usually have like obliquity as well as parallelism, and 



