410 General Nctes, (April, 
They are distinct from the unconformably underlying Taconian 
quartzites, marbles and schists (Lower Taconic) which the author 
regards as Precambrian, and the still older crystalline schists of 
the Atlantic belt, including those, chiefly of Huronian age, whi 
have been called “Altered Quebec group.” The name of Taconic 
cannot be retained for the Appalachian Cambrian, which was, a 
- early as 1861, correctly claimed by Emmons as belonging to the 
period of the first fauna. The Hudson River group, as originally 
defined, included the whole of the Appalachian Cambrian, with 
some portions of the underlying Taconian, and others of overlying 
Ordvician strata, from which in the Appalachian area their char- 
acteristic limestones are wholly or in great part absent. It is 
from solely this association with the Cambrian graywac 
strata of Loraine age that the Hudson River group has come to 
be regarded as the paleontological equivalent of the Loraine. 
In the stable and little disturbed area around the Adirondack 
mountains, including the Champlain and Ottawa basins, the a 
brian is represented only by the quartzites and magnesian !M& 
stones of the Potsdam and Calciferous divisions, which pre 
low-water deposits, corresponding apparently to small Pili = 
only of Cambrian time. The physical conditions of the pa 
sippi area appear to have been similar to that of the Adiron = 
region. As seen to the west of Lake Superior the lowest kent 
dam beds of Hall rest unconformably upon the great Aa 
or copper-bearing series. This, although containing, ©” jije 
fauna. In this north-western area we find, moreover, 
Cambrian horizon, representatives of the Laureni 
Norian. The latter in the typical norites or so-call nian else 
which, near Duluth, are directly overlaid by the Kewet re also 
where resting on Laurentian or on Huronian rocks. i 
are found in Wisconsin petrosilex rocks of Arvoniat YP? ty 
quartzites, rising from beneath the Cambrian sanda his afeh 
ical Montalban and Huronian rocks also occur ere Animikie 
besides the group which the speaker long since ca rlaid i 
This great series, of many thousand feet, which !s e rdiag © 
formably by the Cambrian sandstones, and also, artzites ad 
Irving, by the Keweenian, consists chiefly of qu sponge b? 
argillites with beds of magnetite. The remains of ae at Thomp 
been detected in a calcareous mass got by the spea a late com 
son, Minn., from the argillites of this series, whi Í ia referred 
munication to the National Academy of Science, stated bis . 
to the Lower Taconic or Taconian horizon. + a en Animik? 
conclusion, drawn from various facts, that while ths onia, 
. u $ 
rocks rest unconformably in this region upon yE the coma? 
two series have hitherto been confounded unde 
name of Huronian. 
