QUEBEC GROUP IN GEOLOGY. 3 
3. The relations of the Levis, Lauzon and Sillery of the fossiliferous belt to each other, 
and to the adjacent Potsdam, Calciferous and Trenton formations on the north-west side of 
the St. Lawrence and Champlain fault. ; 
4. The character, direction and effect of this and other large N. E. and 8. W. faults 
which have traversed the region. 
Before proceeding to state the facts and conclusions which I have to bring forward on 
these several questions, it seems necessary to say a few words in explanation of the reasons 
why, after the lengthened and careful investigation which had already been made by Sir 
W. Logan, I should have considered it necessary personally to investigate the facts on 
which the conclusions of my predecessor—as detailed in the Geology of Canada, 1863, and 
in other published reports of the Survey—were founded and which have been more or less 
generally accepted by geologists. Shortly after my arrival in Canada in 1869, I became 
aware, in conversation with Sir W. Logan and Dr. Sterry Hunt, that a difference of opinion 
had then recently arisen between them on certain very important points on which agree- 
ment had previously existed in regard to the structure of the region under consideration. 
The change of opinion was on the part of Dr. Sterry Hunt, and I said that if correct it 
amounted to a complete upsetting of the previously expressed joint conclusions of Sir W. 
Logan and himself, as expressed in the Geology of Canada, 1863. 
About the same time, early in 1870, the first copies of the geological map of Canada 
were issued, on which the structure, as then worked out, was depicted, and another and 
more detailed map of the Eastern Townships was being prepared. This latter map embraces 
26,121 square miles of the Province of Quebec. It is bounded to the south and east by the 
States of New York, Vermont, New Hampshire and Maine; and from 8. W. to N. E. it 
includes the course of the St. Lawrence River from the east end of Lake St. Francis to Cape 
Tormentin, a distance of 212 miles. 
On it are sh2wn with far greater precision than they could be on the published map, 
on a scale of 25 miles to one inch, already mentioned, the details of the distribution of the 
several divisions of the so-called “ Quebec Group,” and also of the Laurentian, Cambrian, 
Cambro-Silurian and Silurian Systems, the Cambrian and Cambro-Silurian being composed 
of the Potsdam, Calciferous, Chazy, Trenton, Utica and Hudson River formations. This 
latter nomenclature was adopted by Sir William Logan for the prolongation of these forma- 
tions in Canada. The Quebec Group was considered to be the equivalent, or nearly so, in 
time of the Calciferous and Chazy formations ; but to be separated from them by a great 
north-east and south-west break or overlap, the result of which has been to bring these 
(see page 20, Geology of Canada) lower members of the series i.e. Calciferous and Chazy, 
or their supposed equivalents, Levis, Lauzon and Nillery, into direct contact, from Lake 
Champlain to the north end of the Island of Orleans, with the highest member of the 
Cambro-Silurian system, the Hudson River formation, and this theory of the structure was 
in 1870 represented both on the published and unpublished geological maps of the region. 
The first effect of Dr. Hunt’s change of opinion was to delay the publication of the 
detailed map, and the second to cause Sir William Logan personally to re-examine the 
ground, being assisted in this work by one of the members of the Geological Survey staff. 
My own attention at that time had to be devoted to distant parts of the Dominion, British 
Columbia, the Maritime Provinces and the North-West. 
