J. LeConte— Formation of the Coast Range of California. 299 



of horizontal mashing must have been enormous. Estimating 

 in the usual way, i. e., taking the present length of the folded 

 strata as the original length of the strata when horizontal, there 

 must have been fifteen to eighteen miles of original sea-bottom 

 crushed into six miles, with corresponding upswelling of the 

 whole mass.* I say estimating in the usual way: for the real 

 breadth of the original sea-bottom was probably considerably 

 less, since as I shall show hereafter, the strata themselves are 

 probably lengthened in the direction of the dip. 



Nor is this particular section an exaggeration of the general 

 structure of this range. On the contrary it is far less complex 

 here than elsewhere. A glance at Whitney's map of Central 

 California will show that the range is small and low at this 

 part. This exceptional lowness is due primarily to the less 

 horizontal mashing, and therefore less upswelling^ and therefore 

 Uss complexity of folding, and therefore less metamorphism, and 

 therefore less hardness of the rocks, and therefore also greater 

 erosion of this part. Whitney has nowhere attempted to give a 

 general section of this very complex range, but in fig. 1 on p. 



14 of vol. 1, of the G-eological Survey, he gives a section of a 

 small portion of the Contra Costa hills farther north, which 

 shows much more crushing than any portion of the range cut 

 by the railroad. 



The diagram section is supposed to be made at right angles 

 to the general trend of the range, i. e., northeast and southwest. 

 The folds are of course represented as striking in the direction 

 of the range, and dipping in the direction of the section. This 

 is very decidedly the average direction of the folds; but there 

 is considerable variation to either side of this average direction. 

 This shows that the horizontal or folding pressure came from 

 several slightly different directions, perhaps consecutively. 

 The same is clearly shown in the external features, also, of this 

 very complex range ; for the sub-ranges and ridges of which it 



15 composed trend in many different directions. 



But there is another minuter structure which I have observed 

 in some of the strata, both of the Contra Costa and the Mt. 

 -Diablo sub-ranges, which demonstrates, in the completest man- 

 ner, the mashing together horizontally and the extension verti- 

 cally, even of the constituent particles of the stratified sediments. 



* In my paper " On the great Lava flood of the northwest," this Journal, I 



