THRUST-FAULTS OF THE NORTHERN ROCKIES 



267 



northwestern Montana 

 .and has been traced 

 northward into Canada. 



Near Philipsburg, 

 Montana, a thrnst-zone 

 comprising two princi- 

 pal and several minor 

 faults has been de- 

 scribed by Calkins,'^ 

 ivho considers it prob- 

 able that this zone is a 

 southerly continuation 

 of the Lewis overthrust. 

 According to Calkins, 

 this fault-zone is an 

 early tectonic feature, 

 since the fault-planes 

 liave been folded and 

 dislocated by normal 

 faults to nearly the 

 same extent as the rock 

 strata. 



The Lomhard over- 

 thrust, as described by 

 "Haynes," has a length 

 •of about 13 miles and a 

 maximum displacement 

 along the fault-plane of 

 about 2 miles. 



The Beartooth fault, 

 along the northeastern 

 border of the Beartooth 



® W. H. Emmons and F. C. 



•Calkins : Geology and ore de- 

 posits of the Philipsburg 

 quadrangle, Montana. U. S. 

 Geol. Survey Prof. Paper 78, 

 1913, pp. 146-150. 



T W. P. Haynes : The Lom- 



"bard overthrust and related 

 geological features. J o a r. 

 Geol., vol. 24, 1916, pp. 269- 



.290. 



d omi nion of cana da 

 '"united 



Figure 1. — Distribution of the knoicn great OvertJirusts 

 in the northern Rocky Mountains 



