216 
THE GEOLOGIST, 
stone (containing gi'eat numbers of encrinites) belonging to the 
Niagara group of rocks. The limestones of this formation constitute 
an elevated plateau at the Falls of Niagara, and running along the 
south-west border of Lake Ontario for a short distance, they form a 
terrace which continues in a north westerly direction to Cabot's Head 
in Lake Huron, and also of the Manitoulin Islands. Mr. Murray has 
sho^vn that the rocks of this group here form two separate and dis- 
tinct terraces, the lowest is the most decidedly marked escarpment, 
exposing strata below the cherty limestone bands which cap the 
precipices at Flamboi'o West ; whilst the upper, composed of the 
bituminous limestones and shales, rises more gradually in a succession 
of steps, terminating at the summit in a vast extent of table land.* 
The crest of the lower escarpment is formed of the massive beds of 
encrinal limestone, passing below the cherty band just mentioned, and 
runs north from Flamboro Bast, and they gradually increase in thick- 
ness as they advance to the northward. Thus, in the seventh con- 
cession of Nassagaweya, there is a vertical precipice of tliis encrinal 
limestone, from eighty to one hundred feet in height ; and in the 
fourth concession of Eramosa, a branch of the river Speed runs be- 
tween vertical and solid calcareous chlFs of sixty to eighty feet. In 
Caledon, the river Credit is flanked by similar clifis one hundred feet 
high, which meet and form a crescent shaped precipice, after ascend- 
ing the valley, over which the river is precipitated in a cascade ; in 
the valley of the Nottawa, in Mono, the same character prevails. 
Similar chfFs were observed in the townships of Mulmer and Notta- 
wasaga ; and in the valley of the Beaver River, in Euphrasia and 
Artemisia, the same limestone is described as one hundred and 
twenty feet thick. If a line is drawn on the map almost due north 
from West Flamboro to Nottawasaga Bay, (the most southern 
boundaiy of the Georgian Bay), it will intersect the first six town- 
ships named, although they lay in four counties. The two last 
named to^vnships lay a little fui-ther westward, and form the extreme 
western boundaiy of the county of Simcoe. A good view of the 
upper half of this interesting part of the countiy is given in a sketch 
of the valley of the Nottawasaga, by Mr. Sandford Fleming in the 
first volume of the first series of the " Canadian Journal," p. 223. 
It is at the base of this limestone, the course of which has just 
been described, that a great series of huge caverns have been dis- 
covered, the roofs of which are studded with stalactites. The most 
evtensive of those that were visited by Mr. Murray w^ere what I shall 
for the present call the Mono and Eramosa caverns. 
The Mo7io Cavern is situated on the twelfth lot of the second con- 
cession, east of the Hurontario Road, in the township of Mono, which 
forms the south-west angle of the county of Simcoe, on a branch of 
the Nottawasaga river. 
The Eramosa Cavern occm's in the fourth lot of the fourth con- 
cession, in the township of Eramosa, county of Waterloo, on a branch 
* Geol. Survey of Canada. Report for 1850-51. 
