236 



E. T. Long — Minor Faulting 



In the Encrinal bed the dip of the fault plane is 22° 

 to the north and 30° to the south, but as soon as it enters 

 the shale below it swings around and within a couple 

 of feet has assumed a 20° dip to the north instead 

 of 30° and a 10° dip to the north instead of 22°. 

 At the intersection of the faults some of the rock is 

 broken away, which may give a false impression, but by 

 projecting the fault planes across the intersection it would 

 appear that the plane C D was the older, though older 

 possibly only by the time it takes to make a fault, for it 

 seems to be cut by the plane A B with a slight offset of 

 not more than 1". The wedge has been raised about three 



Pig. 5. — Eesults of pressure applied to a block of plaster, wax and resin, 

 in an experiment of A. Daubree. Notice the wedge block so similar to Fig. 

 4 above. 



inches and the striated columnar structure indicates 

 movement in a direction about N 15° E, the strike of the 

 planes being approximately N 75° W. Owing to the posi- 

 tion of this and several nearby faults accurate measure- 

 ments were impossible. A comparison of fi*g. 4 with 

 fig. 10 in the article on " Low- Angle Faulting" by 

 Mr. R. T. Chamberlin and Mr. W. Z. Miller 4 will at once 

 prove interesting and instructive. Here in nature is a 

 striking demonstration of the trustworthiness of their 

 experiments. Of course one of the intersecting faults 

 must be eliminated in one's mind to make the analogy 

 really good. 



But this little fault goes even farther. Traced back and 



4 Chamberlin, E, T., and Miller, W. Z., Jour. Geol., vol. 26, p. 27, 1918. 



