12 Captain Bayfield on the 
ahd columnar precipices, frequently 1000, and, at Thunder 
Cape 1350 feet above the lake. It forms almost the whole 
of the Pie Island the south side of which is a precipice from 
500 to 800 feet high. This precipice displays a beautiful 
geological section of the island. In some parts stratification 
is visible half way up the cliffs ; but, in general, only near the 
water. The strata near the water were alone accessible, 
they were of clay slate dipping tothe NE: or nearly so, at 
an angle of about 10° with the horizon. These strata support- 
ed immense masses of greenstone of a pilastered or columnar 
structure, displaying no signs of stratification. 
Greenstone is found associated with the granite from one 
end of the north coast to the other. 
We venture it as our opinion, that this greenstone, which 
passes into sienite, and thence into sienitic granite, should 
be classed as we have done, separately from the trap green- 
stones and sienites, which are associated with the amygda- 
lJoids and porphyry, and which in general occupy, excepts 
ing in veins, a comparatively lower elevation, ‘The green- 
stone which we have placed in the submedial order, mere- 
ly for distinction, and without pretending that such classifi- 
cation is undoubtedly correct, or to decide that which is still 
matter of dispute with geologists, is found in immense beds, 
forming chains of precipitous hills, many miles in extent, 
sometimes alternating with, and sometimes overlying the 
granite, frequentiy at an elevation exceeding 1000 feet above 
the lake. Doctor Bigsby is of opinion that this rock is 
stratified: and so we think, but so very indistinctly and irre- 
gularly, that we will not venture any other opinion, than that 
its general direction is from northeast to east. Common jas- 
per, coated with reddish iron ochre, flinty greenstone, chlori- 
tic, micaceous, and talcese slates, occur in considerable 
quantity 
os ee 
