18 
MUSEUM BULLETIN NO. 2. 
Sill “A,” the highest in the series, consists of an upper gabbro 
phase of specific gravity, 2-96, having a thickness of 26 feet 
and passing gradually downwards into a granite (micropegma- 
tite) interior whose specific gravity is 2-76. This finally 
gives way to a lower gabbro zone of specific gravity 2 * 97, about 
29 feet thick. Underlying this sill occur 80 feet of argillaceous 
quartzites. Sill “B,” of specific gravity 2-93, 30 feet in thick- 
ness, now occurs and in turn is underlain by 670 feet of quartzitic 
sediments. At this point sill “C” makes its appearance and 
has a total thickness of 910 feet, containing an upper granitic 
(micropegmatitic) zone, 310 feet thick, of specific gravity, 2-74, 
passing gradually downwards into hornblende gabbro approx- 
imately 590 feet in thickness. Intervening between sill “C” 
Scale of iV!i(es 
o fa Yg 1 'A i 
4 • u l 
Fig. 2. Natural section of Moyie Sills. See also Figure 3. 
and sill “D” occurs 75 feet of argillaceous quartzites. Sill “D” 
is 1500 feet thick, and was poorly exposed. It consists of horn- 
blende gabbro of specific gravity, 2-99, no large mass of biotite 
granite (micropegmatite) being present in this sill. In the section 
at the Boundary line no further outcrops of gabbro were seen, but 
Daly, from his study of the region to the south, postulates 
another sill, “E”, as the lowest sill in the Moyie group of sills. 
A summary description of the rock types mentioned above 
has been given under “lithological characters” and will not be 
repeated here. It will be noted in comparing Daly’s columnar 
section of the Moyie sills with the one accompanying this paper, 
that there is a difference in the respective thicknesses of sills 
“C” and “ D.” Daly estimated his thickness in the field, while 
