Triassic Tra2)s of Nova Scotia^ etc. — Marsters. 145 
uents as the diabase from "Blomidon" it does not present the 
same fades of the typical diabase as described above. 
The second eruptive mass referred to was found high up the 
west branch of Barney's river. The dike, so far as could be 
seen in the river bed has attained a width of some fifty or sixty 
feet. On either bank, however, it presents the appearance of 
an overflow. The greenish argillaceous slates in which the 
dike is situated are thought by Mr. Fletcher ' to be upper 
Clinton. At the point of contact with the dike the slates were 
considerably altered but so far as could be observed were not 
disturbed to any great degree. On account of the dense forest 
on either side of the stream I was unable to trace it beyond 
the banks of the picturesque gorge. 
A microscopic examination proves the rock to be a feldspar 
porphyry containing also well developed crystals of augite 
and magnetite. The phenocrysts of plagioclase which are 
mainly idiomorphic are considerably altered, but not to such 
a degree as to obliterate under polarized light their twinning 
and apparently zonal structure. Much fine dust, probably 
magnetite, is included in the plagioclase in much larger quan- 
tities in the central part than in the periphery of the individ- 
ual crystal. The augite which is also idiomorphically devel- 
oped shows occasional corroding effects and nearly complete 
alteration to a brownish isomorphous product. The average 
size of the individual is about 2.5 m. m. in length by 2 m. m. in 
width. In one individual a peculiar instance of twinning 
apparently on the clino-pinacoid was exhibited, but sufficient 
data could not be obtained to prove beyond doubt the accuracy 
of the above statement. In addition to the fine magnetic dust 
already mentioned there was also shown almost perfect 
octahedra a few of which were included within the pheno- 
crysts of augite. 
At present the writer is unable to connect this dike with 
any parent eruptive body. He is of the opinion that an 
extended search will prove that it, together with other numer- 
ous eruptive rocks described by Mr. Fletcher, may have some 
connection with a parent body which was the central point of 
eruptive and intrusive action. 
Geological Laboratory , Cornell University^ Dec. 4th, 1889. 
•Report of progress 1886. p. 45, P. Canad. Geol. Survey. 
