304 GEOLOGY AND MINERALOGY. 
NOTES ON THE GEOLOGY OF THE BLUE MOUNTAIN ESCARPMENT, IN COLLINGWOOD 
TOWNSHIP, CANADA WIEST.—BY E. J. CHAPMAN. 
1. The elevated tract of land, known popularly as the “ Blue Mountains,” in 
the Township of Collingwood, C.W., and which forms a somewhat striking feature 
in the scenery of that district, constitutes a spur (or more properly, perhaps, the 
north-eastern point), of the line of escarpment which runs from the western 
extremity of Lake Ontario to the western shores of Georgian Bay: its face being 
opposed, generally, to the east or north-east. The range of this escarpment north 
of Dundas was briefly pointed out by Mr. Murray, of the Geological Survey, in 
his Report for 1850-1. It has also been laid down by Mr. Sandford Fleming in a 
small railway-map published in 1857. The Report accompanying Mr, Fleming’s 
map contains, in addition, a slight but substantially correct sketch of the general 
geological features of the surrounding district. In Mr. Murray’s Report, the for- 
mations west of the escarpment (commencing with the Upper Silurians) are alone 
considered. 
2. Near the base of the “ Blue Mountains,” on the shore of Nottawasaga Bay, 
the Trenton Limestone constitutes the lowest visible formation. This, which at 
the spot in question scarcely appears above the ordinary level of the lake, is 
succeeded by interstratified beds of bituminous limestone and bituminous shale, 
belonging to the base of the Utica Slate series. This peculiar interstratification 
of shale and limestone is alluded to by Mr. Murray in his Report (for 1848-9) on 
the shores of Georgian Bay and the west coast of Lake Huron. Three fossils are 
especially abundant in these beds, viz.:—Zriarthrus Beckiz, Asaphus Canadensis, 
and a Lingula allied to ZL. obtusa, if not identical with that species. Another 
lingula; Z. guadrata, is also not uncommon. The trilobites are usually in a 
fragmentary condition: the glabella, &e., of ZY. Beckii, and the pygidium of 
A. Canadensis, being the parts commonly met with. The lingulz, on the con- 
trary, are beautifully preserved ; and their dark, lustrous shells stand out in strong 
relief on the light gray weathered surface of the rock. Orthis testudinaria is 
also of not uncommon occurrence; and, in some beds, ill-preserved graptolite 
fragments, belonging apparently to G. pristis, are occasionally met with. A 
small species of Leperditia is likewise present in great numbers. It is identical 
with that first discovered in the Utica Slate of Western Canada by Mr. J. F. 
Smith, and which is still, we believe, without a specific name. 
3. The Utica Slate deposit, comprising altogether a thickness of about seventy 
or eighty feet, passes under the Mountain, and is succeeded by greenish and other 
colored arenaceous shales or thin-bedded sandstones belonging to the Hudson 
River group. This latter formation appears (at this locallty) to constitute the 
chief mass of the mountain. Its thickness cannot be far short of 650 feet. On 
the northern face of the escarpment it is exposed in several gullies, but it yields 
scarcely a trace of fossils: an indistinct ambonychia radiata and some faint grap- 
tolite markings were alone obtained. Farther west, as where the formation 
comes out on Georgian Bay, and at Owen Sound, fossils occur in it, however, in 
some abundanee. 
4. On the top of the mountain, some exposures of siliceous limestone occur. 
These beds belong undoubtedly to the Clinton sub-formation; so that, between 
