CHANGES IN THE STRATIFIED ROCKS 291 
rocks, their effect is relatively simple, but when they 
cut inclined or folded strata, it is often exceedingly 
complex. They produce a variety of effects accord- 
Diagram of faulted region in Connecticut valley, Conn., showing section of 
faults and the erosion surface with the discordance of strata on the two sides 
of the fault-planes. 
ing to the direction they pursue and the angle of 
their hade. When a faulted region is planed down 
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re: 
Fie. 173. 
Cross-section of overthrust faults. Thrust planes, 4B and CD. 
by erosion, the strata are raised in sharply discord- 
ant positions, so that it is often difficult to piece 
them together and to see what their original position 
