STRUCTURES COMMON TO ALL ROCKS. 241 



which mountain-ranges seem to have been formed. Some- 

 times, though rarely, there is but one great fold (Fig. 

 144) ; sometimes there are several open folds (Fig. 145) ; 



FIG. 145. Section across the Jura. 



more commonly, especially in great mountains, there are 

 many closely appressed folds (Figs. 146 and 147). In 

 the Coast Range (Fig. 146) there are at least five alternate 

 anticlines and synclines ; in the Alps there are, in some 

 places, seven alternate anticlines and synclines. It is 



PIG. 146. Section of Coast Range, showing plication by horizontal pressure. 



evident that in these cases a great breadth of sediments 

 is squeezed horizontally into a small space, and corre- 

 spondingly swelled upward into a range. In the case of 

 the Coast Range (Fig. 146), every two or two and a half 

 miles of original breadth has been compressed into one 



FIG. 147. Appalachian chain. 



mile. In the case of the Alps, probably every three miles 

 of original breadth has been crushed into one mile, and, 

 of course, correspondingly swelled up. Sometimes the 

 mashing together is even far greater than represented in 



LE CONTE, GEOL. 16 



