388 



THE GEOLOGIST. 



the eastern townsKips and forms many isolated hills, the whole of them of 

 small size with the exception of the Great Megantic Mountain, which 

 occupies an area of about 12 square miles. It is composed of white quartz 

 and white orthoclase feldspar, with black mica. An area of this rock 

 occurs in Stanstead, covering 6 square miles, and forming Biby Plains. 

 Another occurs in Barnston, from which the second sample exhibited has 

 been taken. Granite of the ^ame character, and probably of the same age, 

 is widely distributed in the State of Maine, and is traceable to New Bruns- 

 wick, where it is overlaid by the carboniferous rocks. 



Marbles are exhibited from the Laurentian, Quebec, Chazy, Bird's Eye 

 and Black Eiver, Trenton and Upper Helderberg formations ; and ser- 

 pentine from Oxford, Melbourne, and St. Joseph Beauce. The band of 

 serpentine from difierent places on which the samples have been obtained 

 has been traced on the south side of the St. Lawrence, from Potton 

 to Cranbourne, 140 miles ; in 40 miles of which it is twice repeated by 

 undulations, giving an additional 80 miles to its outcrop. It is again 

 recognized 250 miles further to the N.E. in Mount Albert, on the Sliick- 

 shock Mountains, and about 70 miles further in Mount Serpentine, 

 approaching Gaspe Bay. All the specimens of the rock which have been 

 analysed contain small quantities of chromium and nickel, and the band is 

 associated in its distribution with soapstone, potstone, dolomite, and mag- 

 nesite. The whole of these occur in large quantities, and in them as well 

 as in the serpentine chromic iron occurs, sometimes in workable quantities. 



These rocks or others immediately near them contain the metals iron, 

 lead, copper, nickel, silver, gold, and with the drift-gold derived from these 

 beds are platinum, iridosmine, and traces of mercury. In 1847 these ser- 

 pentines, from their distribution, were described in the Heports of the Sur- 

 vey as altered sedimentary rock ; and all subsequent observations have 

 confirmed this view. Regularly stratified masses have been found in 

 Mount Albert belonging to the Quebec group, 



Eoofing slates are exhibited from a band of slate in immediate contact 

 with the summit of the serpentine. It has a breadth of -i- of a mile, and 

 dips about 80° S.E. Mr. Walton commenced opening a quarry upon it 

 in 1860, and found it necessary, to gain access to the slate, to make a tunnel 

 through the serpentine, to effect which, and expose a sufficient face for 

 working, has taken two years, and cost 30,000 dollars. 



Up to a comparatively recent period, the usual coverings of houses in 

 Canada have been wood, shingles, and galvanized iron or tin plate ; but so 

 many fires have happened by the use of the former that they are now 

 interdicted in all large towns. Those exhibited are from Mr. Walton's 

 quarry, which has now been in operation since 1861, and these slates are 

 now being sent to distances of more than 500 miles. The strong re- 

 semblance between these Melbourne slates and those from Bangor, in 

 Wales, and Answers, in France, may be seen by the following analyses by 

 Mr.E. SterryHunt:- 



Welsh. French. Canadian. 



Silica 60-50 57-00 64-20 



Ahimiua 1970 20-10 16-80 



Protoxide of Iron . 7-83 10-98 4-23 



Lime 1 12 1-23 0 73 



Ma2;ncsia 2-^0 8-89 3-94 



Potash 3-18 1-70 3 26 



Soda 2-20 1-30 3-07 



Water 3 30 4.40 3 40 



100 03 



99 63 



