REVIEWS 199 
to granites, syenites, diabase, gabbro, etc., where complete hydrothermal 
fusion took place. 
II. TACONIC 
This is considered as the time equivalent of the Lower Cambrian, 
and is separated from the Upper Kewatin by a marked unconformity. 
It is separated into two divisions, the Animikie and the Keweenawan. 
1. Animtkie.—The Animikie consists of a series of graywackes, 
slates, and quartzites, and the Mesabi iron ore series. The beds vary 
in dip from nearly horizontal to 45°. There are no known contem- 
porary lava flows, but the rocks are characterized by the presence of 
numerous sills and dikes of diabase intruded during the interval 
separating the Animikie from the overlying clastics (Potsdam). 
2. Keweenawan.—The clastic part of the Keweenawan is consid- 
ered as Potsdam and is separated from the Animikie by a distinct 
unconformity. It begins with a basal conglomerate, usually red in 
color and of varying coarseness, known as the Puckwunge conglomer- 
ate, and is followed by quartzites and sandstones interbedded with 
lava flows of great volume and extent. The sedimentary beds became 
progressively thicker as the igneous activities waned, finally terminating 
in the white and siliceous sandstone of the overlying formation 
(Upper Cambrian). The dip is even more gentle than in the 
Animikie. 
The eruptives of the Keweenawan are divided into two divisions, 
the Cabotian and the Manitou. 
(a) Cabotian.—The Cabotian includes the great masses of gabbro, 
anorthosyte, diabase, etc., which in time of origin immediately ante- 
date the Puckwunge conglomerate. In consequence of the great 
extrusion of igneous material, designated as the “great gabbro revolu- 
tion,’ large areas of the Animikie were covered with heated lavas, 
resulting in the fusion of considerable portions of the former. Con- 
temporary with this flow there were also important intrusions of 
gabbro as sills and dikes in the unfused portions of the series. 
(6) Manitou.—The Manitou series is made up of a great number 
of surface flows, showing amygdaloidal and brecciated partings, and 
alternating with beds of sandstone in the upper portion. The first of 
the series appear as contemporaneous beds associated with the basal, 
or Puckwunge conglomerate, but the greater part of the eruptives are 
of a distinctly later date. 
