Triassie Traj^s of Nova Scotia, etc. — Marsters. 143 
So far as the writer is acquainted no microscopic descrip- 
tions of the Triassie traps of the North mountains or of any 
of the intrusive rocks of Nova Scotia have been published. 
Although I find in the "Canadian Reports of Progress" nu- 
merous references to d5'kes, granitic bosses, and trappean 
areas, yet seldom more than a very general macroscopic de- 
scription, and occasionally only the location is given. Hence 
extended examination of this province Avould undoubtedly 
furnish much interesting material for microscopic investiga- 
tion. The writer therefore hopes that in the near future he 
may be able to make a closer study not only of the Triassie 
traps but also of other known eruptive rocks in this region. 
The trap, like all those from similar deposits in the United 
States, is a typical diabase. Under the microscope it proves 
to be composed chiefly of plagioclase with generally irregular 
and scattered masses of augite, magnetite, sometimes showing 
perfect octahedral forms but in the main massive, and a brown- 
ish mineral probably resulting from the decomposition of the 
augite. The plagioclase which presents little evidence of de- 
composition consists of lath-shaped crystals exhibiting very 
good crystallographic terminations, They are almost uni- 
versally twinned but seldom exhibit marked zonal structure. 
These sections, approaching the zone of the axis of symmetry 
show a decided fracturing as ifsubjected to great pressure or 
some mechanical disturbance subsequent to the completion 
of their crystalline form. It makes up the most prominent 
component of the rock. Augite exhibits irregular small 
masses with brightly polarizing centers and muddy, dark- 
brown peripheries. The brownish product, which is of sec- 
ondary origin extends along the cracks so universally pres- 
ent in augite, presenting a net-like appearance. Whenever a 
crystal occurred sufficiently fresh and regular in form for 
orientation, it proved to be twinned on the orthopinacoid. 
Magnetite occurs for the greater part in irregular aggregates 
which may be of secondary origin, but not presenting a titan- 
iferous aspect. The perfect octahedra are undoubtedly pri- 
mary and were probably the first to form during the cooling 
of the fused mass. Compared with sections of Triassie traps 
from New Jersey, kindly loaned me by Prof J. F. Kemp,"* I 
* The writer is higlily indebted to Prof. J. F. Kemp for many sug- 
gestions and references to pul>lished matter dealing with similar for- 
mations in U. S. 
