History of the Quebec Group. — Hunt. 213 
We are next invited by the reviewer "to consider the breaking 
down of this elaborately constructed geological group, built 
up by the labors of Sir W. E. Logan and his associates, Mr. E. 
Billings, Dr. T. Sterry Hunt and Mr. James Richardson." Sel- 
wyn, we are told, "began the work of disintegration when he 
showed in his report for 1877-78 that the rocks of the Canadian 
extension of the Green Mountain (or Sutton Mountain) range 
and its northeasterly extension were arranged in an anticlinal 
instead of a synclinal form as supposed by Logan. This re- 
moved the keystone on which the stratigraphic structure of 
the altered portion of the Quebec group was based." The 
crystalline schists were now referred to a "pre-Cambrian 
group, probably Huronian;" and what Selwyn had previously 
called a Volcanic group (unrecognized however by Logan and 
his assistants) was imagined to be pre-Cambrian. 
Besides the false conception with regard to the stratigraphi- 
cal structure, according to Ells, "another source of error, and 
probably the most considerable, was the assumption that the 
metamorphic rocks of that area must of necessity be the equiv- 
alent of the unaltered sediments of the St. Lawrence region, a 
theory which once suggested seems to have been unhesitating- 
ly maintained, although for its support unnecessary inversions 
of strata and profound chemical changes were requisite.'' Still 
farther Ells has shown, according to Walcott, with regard to 
the uncrystalline Quebec group, that "the order of succession 
was inverted by Logan, and that the Levis series is conform- 
ably superjacent to the Upper Sillery (Lauzon of Logan) 
while the Lower Sillery forms the base of the section in the 
vicinity of Quebec." 
There are thus embodied in the preceding paragraphs four 
important propositions : 
1. The crystalline schists of the Green Mountain range and 
of its prolongation northeastwards in the province of Quebec — 
the so-called Altered Quebec group — do not form a synclinal, 
and are not metamorphosed paleozoic rocks, but on the con- 
trary constitute an anticlinal axis of ancient strata, "pru-Cam- 
brian and probably Huronian" in age. 
2. The uncrystalline fossiliferous strata along the western 
and northern flanks of this range are newer rocks of Cambrian 
and Ordovician age. 
S. The order of these newer strata was mistaken by Logan, 
