History of the Quebec Group. — Hunt. 217 
letter to Barrande, dated in 1860 but published March 1861, to 
the effect that certain fossiliferous strata included in the Hud- 
son-River group at Quebec had long been maintained by Em- 
mons to be older than the Trenton, adding ''The fossils which 
have been obtained this year [1860] at Quebec pretty clearly 
demonstrate that he is right." Instead, however, of calling 
these Upper Taconic with Emmons, or First Graywakce with 
Eaton, Logan proposed in his letter to Barrande the name 
of Quebec group, of which the apparently overlying Sillery 
sandstones constituted the summit, the great underlying mass 
of shales and limestone being called the Levis, and an inter- 
mediate division being subsequently proposed with the name 
of Lauzon. With the exception of this change in horizon of 
the group rendered inevitable by the progress of paleontologi- 
cal study, and the corresponding change in name, no alteration 
was made in the views of Logan, which were still those of 
Mather. The Hudson-River group of the latter was found to 
be pre-Trenton and was named Quebec group, and the crys- 
talline schists were henceforth called Altered Quebec group 
instead of Altered Hudson-River group. 
But the way was slowly preparing for the overturning of 
the whole hypothesis of Mather, and the establishment of the 
older view of Eaton and Emmons with regard to those crys- 
talline schists, as well as to the uncrystalline sediments. My 
studies of the crystalline rocks of the Ottawa and the great 
lakes had shown close resemblances between certain of these 
rocks and the crystalline schists of the Green Mountain range 
as seen alike in New England and in Quebec, and I was led to 
consider carefully the teaching of Eaton and of Emmons, that 
this range is itself a primitive or pre-Cambrian axis more 
ancient than the uncrystalline sediments along its western and 
northern base. I had found and described in 1857 in con- 
glomerates interstratified with the fossiliferous beds of the Hud- 
son-River group atPointe Levis fragments of i>urplis]i and green- 
ish lustrous schists, apparently chloritic, and had moreover de- 
scribed in 1861 the presence of pebbles of green and bluish 
slates in conglomerates of the Potsdam age near the outlet of 
lake Champlain ; in both cases evidently derived from rocks 
of greater antiquity, apparently the primitive schists of Eaton.' 
'See History of Cambrian and Silurian in Chemical and Geological 
Essays, page 400. 
