
Buck Mountain Fault
Sample 13 was collected from the margin of the Buck Mountain fault and shows characteristics of mild fracturting of precambrian plutonic country rock. Substantial crystals of quartz, plagioclase, biotite and sericite make up the plutonic rocks of the Tetons.




North of Buck Mountain the fault cuts like a knife along the western precipitous boundary of the Cathedral Group. Sample 28 was collected right on the cutting edge of the Buck Mountain fault. The rock is crushed and altered compared to the country rock. The thin section shows a fine grained matrix of sericite with floating feldspar fragments.



Another altered rock from the Buck Mountain fault, Sample 29 has a green tinge and displays Chlorite and Epidote in the thin section. This is suggestive of alteration by fluids permeating the rock in a time of shearing forces.




Sample 10 is an example of the pink granodiorite plutonic core of the Cathedral group.



Samples 1 & 42 are highly altered fault rocks from the northwest flank of Buck Mountain on the edge of the Buck-Static divide. They are collected from the intersection of Static fault and Buck Mountain fault. Lots of altered minerals in the matrix and evidence of brittle fracture in thin section…



Sample 5 is from Static fault just west of Buck Mountain. All the signs of alteration are there in the macro and micro examples.


Sample 25 is from Stewart fault which cross cuts the Buck Mountain fault cradling the Cathedral group as it’s southern termination.


