TEKKANES. 



103 



94. 



and faulted in the direction of the thrust, and the beds become stretched 

 and thinned in the process, as explained beyond. 



In Fig. 94, which represents a surface only six feet square, the synclines 

 and anticlines are a few feet only in span ; moreover, as is seen, the little 

 anticlines have still smaller anticlines and 

 synclines subordinate to them ; so that the 

 figure represents compound flexures. But 

 these small flexures at the locality are 

 subordinate to the great flexures of the 



region, which are thousands of feet in 

 span, so that they are portions of a 

 doubly -compound system of flexures. 



Since flexures are greatly disguised, as 

 explained above, so that the kind is seldom 

 indicated in the exterior form, their nature 



has to be learned from the dip and other characters of the associated beds. 

 A portion of a flexure may be mistaken for a monocline unless the region is 

 well studied. 



Fig. 95 represents the rocks with their true dip along 4 parallel sections across a 

 country, the blocked areas being limestone and the others mica schist. They show 

 what may be the actual appearance of a region of folded rocks after it is worn down 

 to a nearly level surface. All that is visible over the region is the upper surface and 

 enough below it to give the true dip ; and from these facts and the study of the characters 



95. 



iiUj^ ii \\^E.Sch. 



ZSch 



ZSch 



ISch 



maminm 



E.Sch. 



it-:^ 



SSch. 



»• Sch 



m. 



Hm ' ""m^p^^^^^^ ^^^m^ 



/E.Sch. 



^•im 



3 Sch. 



■ St.A. L 





Flexures in limestone and schist, Westchester Co., N.Y. D. '81. 



of the beds throughout the region, the kinds of flexures are deduced. The dotted lines 

 show one interpretation of the facts. The synclinal near the middle of section 1 is over- 

 laid by schist in 2, and by still more schist in 3 and 4 ; and changes occur also in the other 

 flexures. But other interpretations are possible. 



