NV. W. Portion of Lake Huron. 269 
The other long side possesses the same geological fea- 
tures as the one just described. The breccia perhaps 
abounds more here. The slaty portions are found at 
tevel and at one place in strata two feet thick. About the 
middle there is a cave, about three yards in its great- 
est depth, formed by the concurrence of several of the cay- 
ernous, bowl-shaped hollows, thus creating one of great di- 
mensions ; 3; whose interior is subdivided into smaller cavities 
seri 
The beach is covered almost exclusively with limestones 
slaty, vesicular and brecciated. I saw the vesicular species 
after it had been exposed to the heat of a kiln. It had suf- 
fered a change of colour only from its ochry event to a 
rown or black. 
The stratified limestone burns profitably. 
- ‘Two, if not three eras and modes of formation ie 
clearly distinguishable. The first and oldest is the slate, 
which is seen to floor the lake for miles around. Upon it 
are supported two calcareous masses which mingle with 
each other and with short slips of the schist in the greatest 
disorder; and having a few of the broken flints interspers- 
ed. In all ability they are veins of strata which have 
been overw — by a sudden violent force. _ 
e been the means of comminuting, 
and partially se this bed of limestone. Steam, a prin- 
cipal agent, may have insinuated itself into the more yield- 
ing portions ; and the whole, has finally, consolidated. , 
nag 
The conglomerates are curious, and are met with 
cipally in the shape of debris. Their heir matrices are 
kinds, and greenstone. The quarizose species ¢ ee 
hibits three forms—its nodules are sometimes exclusively, 
translucent white quartz. In other i instances a are mass- 
es of greenstone; but by far more y 
