236 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 

 Table XII. — Chemical analyses of Phases of the Moyie Sills. 



The two tables illustrate the abnormal character of every one of the rock 

 types occurring in these sills. The tables also show the great range of rock 

 variation. The changes in mineralogical and chemical composition and in 

 density are clearly systematic in the series from gabbro, through intermediate 

 rock, to hornblende-biotite granite, and then to biotite granite. It now remains 

 to indicate that the same serial arrangement characterizes the rock-zones in 

 each of four of the sills; and that there is an analogous series in passing 

 upward from sill E, through ?ill D to the top of sill C. 



ESSENTIAL FEATURES OF THE DIFFERENT SILLS. 



The reader will readily seize the situation by a glance over the following 

 stratigraphic column (Table XIII) and the corresponding diagram (Figure 

 15). At the top of the column is the recently discovered sill A with its cap 

 of quartzite; at the bottom is the quartzite underlying sill E at the valley floor 

 west of Moyie mountain. It should be noted that thicknesses of sills and zones, 

 and the positions of type specimens have been determined only with approxi- 

 mate accuracy. The section described occurs almost exactly in the line of the 

 Boundary slash. 



