The Taconic — Marcou. ' 19 
last "eighty miles of the extremity of Gaspd," which he says 
"are destitute of any clear evidence that true Utica and Hud- 
son River strata occur anywhere along the south side of the St. 
Lawrence from Gaspd to Quebec." [ Ch. Lapxvorth^ On grap- 
tolites fi'om Lower Palceoz. rocks^ 1886.] The finding of great 
faults where before "the most able stratigraphical geologist of 
the American continent," had found only a perfect concordance 
in the stratification, was not the only change in "the principles" 
of the adversaries of Dr. Emmons; Logan transported the 
"Olenus zone" from the tojD of the Lorraine shales, that is to say 
above the second fauna, to its base, and put it in the Potsdam 
as a subordinate part; and then created a new great division of 
strata which he called "Quebec group," placed between the 
Potsdam and the Birdseye, Black River and Trenton, and as an 
equivalent of the Calciferous and Chazy divisions. 
In 1 86 1, during his first visit at Georgia, Marcou recognized 
that the "Olenus zone" is not a part of the Potsdam, but far 
below, in the middle of the Taconic. He referred also a part 
of Point L^vis formation to the Taconic. 
In 1862, after two explorations at Quebec and in the north- 
western pait of Vermont, Marcou gave "comparative tabular 
sections of the upper Taconic [or true Taconic] rocks in Ver- 
mont and Lower Canada" in which he creates the Phillipsburgh 
and point L^vis group, and Swanton slates, or city of Quebec 
group, placing them between the Potsdam sandstone and the 
Georgia slates, as the upper part of the Taconic. He also calls 
attention to that great stratigraphical fact, unknown until then, 
of the existence at different levels of the Taconic, of lenticular 
masses of limestone, marble, sandstone, varying in size from a 
fist to masses several thousand feet in length, and a hundred feet 
thickness. After a stay of several months in 1873 and 74 at 
Higngate Springs, Vt., Marcou came to the conclusions that 
the sporadic second fauna fossils, found in some of the lenticu- 
lar masses of limestone, are only colonies inclosed in the Phillips- 
burgh and Swanton groups; and that all the second fauna fos- 
sils found in the upper Taconic are only precursors of the second 
fauna inclosed in the supra-primordial fauna, where these are 
mixed, more or less according to localities, with primordial fos- 
sils, such as: Olenellus., Dikelocephalus^ Arionellus^ Bathyurus^ 
