2 
MUSEUM BULLETIN NO. 2. 
merging irregularly into micropegmatite, forms a zone in the 
uppermost part of the sill, while a fourth zone of rock inter- 
mediate in composition between the granite and gabbro and, on 
the respective sides, transitional into those rocks, occurs between 
the thick basic zone and the much thinner granite zone.” 
« 
(2) “The sedimentary formation cut by the sill comprises a 
very thick series of ancient sandstones highly quartzose but 
generally containing alkaline and soda-lime feldspars and always 
carrying mica.” 
(3) “At the time of intrusion the quartzitic strata lay flat.” 
(4) “At both contacts of the sill, the igneous rock contains 
foreign blocks shattered off from the quartzites. These blocks 
often show evidence of magmatic corrosion.” 
(5) “The field-relations and the chemical and optical study of 
sill-rocks and quartzites suggest that the material of the granite- 
micropegmatite zone is of derived origin. Most of that material 
resulted from the solvent action of the gabbro magma on the 
quartzite blocks and on the main sill-contacts. Some of the 
constituent elements of the granite may have been taken from 
the gabbro, which, on account of its superior and great volume, 
shows no appreciable modification by such loss.” 
(6) “The asymmetry of the intrusive body is believed to be 
owing to the stratification of the sill by the action of gravitative 
adjustment. The product of assimilation whether at the lower 
main contact or about quartzite blocks immersed in the gabbro, 
possessed less density than the gabbro magma, rose through 
that magma and collected at the top of the sill. The interme- 
diate rock represents a zone of incomplete differentiation.” 
(7) “The assimilation and concomitant differentiation are 
exhibited in other sills of the region, but, on account of the 
relatively small thickness and consequently smaller share of heat 
energy possessed by those sills, the action did not develop true 
granite.” 
(8) “Following the solidification of these sills, they were 
faulted and tilted to their present position in the fault-blocks 
of the Purcell Mountain range.” 
(9) “More or less perfect parallels to the Moyie sill have been 
described by various workers in Minnesota and Ontario. In all 
