34 
Explanation of Plate I, 
Fig. 1. Photomicrograph of hypersthene gabbro of Purcell Sills. Magnification: 
16 diameters. 
“ 2. Photomicrograph of granite (micropegmatite) of Purcell Sills. Magnafica- 
tion: 16 diameters. 
Fio. 2. 
