BULL. GEOL. SOC. AM. 



VOL. 32, 1920, :^L. 12 



Figure 1. — Platy Parting of a DioRrTE-poRrHVRY Dike, two Miles Southwest of Gold 



Butte Post-Office 



Figure 2. — Distant View of East Butte, looking East 



DIORITE-PORPHYKY DIKE AND VIEW OF EAST BUTTE, SWEET GEASS 

 HILLS, MONTANA 



