390 
THE GEOLOGIST. 
average thickness of 5 feet ; but the most important deposit is that on the 
great slopes of the Beaver Eiver, in Euphrasia and Artemisia, \rhere it is 
supposed to extend over more than a thousand acres, in the form of a strip 
on each side of the river. Under the head of mineral paints we have iron 
ochres of alluvial, and sulphate of barytes of Laurentian age. The 
barytes of Burgess and Lansdowne is derived from veins intersecting tlie 
Laurentian rocks. At both places the mineral, associated with calcspar, 
constitutes the veinstone of some of the lead lodes met w ith, there. The 
vein yielding the Lansdowne specimen cuts Laurentian limestone. In an 
unsuccessful attempt to mine the vein for lead, it was ascertained that 28 
feet of the lode, with a breadth of 27 inches, consisted of highly crystalline 
almost colourless barytes, yielding about 10 tons to the square fathom. 
The most abundant source of barytes in Canada, so far as is known, ap- 
pears to be the veinstones of lodes carrying copper-ore on the north side 
of Lake Superior ; these however belong to the Quebec group. In Canada 
this mineral is not as yet applied to any use, but in some parts of the 
United States it is refined and ground in large quantities for use as a 
paint. 
Amongst the minerals applicable to the fine arts, foremost is the litho- 
graphic stone (Bird's-eye formation) from Marmora, where the Laurentian 
rocks are overlaid by 20 feet of unfossiliferous compact limestone, one of 
the beds of which is well adapted for lithography, and has been traced by 
occasional exposures from Huugerford to Rama, a distance of more than a 
hundred miles. Lithographic stone is also shown from the Onondaga for- 
mation at Brant and Oxbow. 
On the minerals applicable to jewellery we shall not dwell at any 
length. We have agates, labradorite, albite (persisterite), orthoclase (perth- 
ite), jasper conglomerate, epidosite. 
In the miscellaneous minerals we have feldspar (frQm a 20 feet wide 
Laurentian), sandstone for glass-making (Potsdam), moulding-sand (drift), 
and peat (alluvial). The peat exhibited occurs near Chambly, on the south 
side of the St. Lawrence, and was some years ago cut and sold as fuel, but 
the consumption was not enough to encourage the industry. As Canada 
is deficient in coal, when wood becomes scarce in the progress of set- 
tlement peat will gradually assume some importance as a fuel in many 
parts of the country. About 100 square miles of it extends along the 
south front of the Anticosti, and successive areas are met with on the south 
and north sides of the St. Lawrence. Large peat bogs occur between the 
Ottawa and the St. Lawrence, and there are many to the westward. The 
peat, which is sufficiently matted to hold together when dried, usually sup- 
ports a growth of prairie-grass, or ericaceous plants, or of tamarac-trees. 
That which occurs in cedar-swamps is deficient in the fibrous plants which 
give cohesion, and it falls to powder when dried. 
The Survey also exhibits an admirable collection of the crystalline rocks 
of Canada, arranged under these respective groups : — I. Laurentian. II. 
Huronian. III. Lower Silurian ; and IV. Eruptive ; accompanied by an 
excellent catalogue by Mr. T. Sterry Hunt. AVe cannot however give a 
special notice, however richly it deserves it, as we have already devoted a 
very considerable space to the Canadian collection ; but the interest which 
attaches to it as representing that country, where, more than in any other 
part of our globe, the "bottom rocks" of the earth's stratified crust are 
most grandly exposed, warrants the fullest attention ; and the numerous 
facts which are thus briefly but accurately recorded will be found here- 
after of the highest value in considerations of the circumstances producing 
and attending the earliest history of our lowest life-containing and our 
