590 THE JOURNAL OF GEOLOGY. 



short distance forms two east-dipping monoclines, the repetition 

 being caused by a dislocation parallel with the trend of the 

 mountains. The Triassic limestone on Squaw creek also proba- 

 bly owes its preservation to parallel fault lines, for the limestone 

 masses are often on edge, lying unconformably between beds of 

 the older shales. And these limestone masses are never con- 

 tinuous for more than a few miles, there being always an offset 

 between one ridge and the next one to the northward. The 

 limestones were probably faulted down into troughs and thus 

 preserved against erosion. 



The trend of the Carboniferous limestone mountains is north 

 and south, while the strike is always west of north, but exceed- 

 ingly variable. 1 



Between Squaw creek and Pitt river there are at least three 

 parallel north-south fault lines, for the Triassic limestone forms 

 three ridges in which the same dip, order of succession of the 

 various beds, and the same fossils were observed. To the east- 

 ward the Trias is cut off from the Jura by either a fault or an 

 unconformity, for in some places much higher Triassic beds were 

 found than at others at no great distance. But no unconformity 

 by erosion was observed. 



A glance at Fairbanks' geological map of Shasta county 2 

 shows that the system of faults must be younger than the folds. 

 The Carboniferous limestone has a north and south trend ; it is 

 not however continuous, but disappears and then reappears in 

 the same strike in a few miles. But the strike of the rocks is 

 not parallel to the trend of the mountains, being northwest- 

 southeast, while the general dip is to the northeast. 



Since the Carboniferous limestone is in line with a general 

 east dip, and the Triassic nearly parallel with it, also with a 

 general east dip, it seems that the strata of this region were 

 thrown into folds with a northwest-southeast strike, and that 

 afterwards a system of north-south faults or fault troughs broke 



1 California State Mining Bureau, Eleventh Annual Report, 1893, 1894. 

 H. W. Fairbanks : Geology and Mineralogy of Shasta County, p. 37. 



2 California State Mining Bureau, Eleventh Annual Report, 1893. 



