216 



THE GEOLOGIST, 



stone (containing great 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 

 shown 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 ba^nds which cap the 

 precipices at Flamboro 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 lov/er escarpment is formed of the massive beds of 

 encrinal limestone, passing below the cherty band just mentioned, and 

 runs north from Flamboro East, 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 this encrinal 

 limestone, from eighty to one hundred feet in height ; and in the 

 fourth concession of Era^mosa, a branch of the river Speed runs be- 

 tween vertical and solid calcareous cliffs of sixty to eighty feet. In 

 Caledon, the river Credit is flanked by similar cliffs one hundred feet 

 iiigh, which meet and form a crescent shaped precipice, after ascend- 

 :^ng the valley, over which the river is precipitated in a cascade ; in 

 the valley of the ISTottawa, in Mono, the same character prevails. 

 Similar cliffs 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 

 boundary of the Georgian Bay), it will intersect the first six town- 

 ships named, although they lay in four counties. The two last 

 named townships lay a little further westward, and form the extreme 

 western boundary of the county of Simcoe. A good view of the 

 upper half of this interesting part of the country 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 wliicli are studded with stalactites. The most 

 evtensive of those that were visited by Mr. Murray were what I shall 

 for the present call the Mono and Eramosa caverns. 



The Mono Cavern is situated on the twelfth lot of the second con- 

 cession, east of the Hurontario Road, in the_township of Mono, which 

 foi-ms 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 foui-th con- 

 cession, in the to™ship of Eramosa, county of Waterloo, on a branch 



Crcol. Surrey of Canada. Eeport for 1850-51. 



