American Geology, by T. S. Hunt. 399 
Auroral division, consisting of sixty feet or more of reous 
sandstone, the supposed equivalent of the Calciferous aaa 
followed by the Auroral limestone, which is magnesian, 
often argillaceous and cherty in the upper beds. Its thickness 
is estimated at from 2500 to 5500 feet, and it is su e 
Rogers to include the Chazy and Black River limestones, while 
the succeeding Matinal division exhibits first, from 500 
feet of limestone Baybee. secondly, 300 to 400 feet black 
shale, (Utica), ‘ch thirdly, 1200 feet of shales with red slates and 
: conglomerates, (Hudson River Group), thus completing the Lower 
ilurian series, 
In Eastern Tennessee, Mr. rare describes (Ist.) on the con- 
fines of North Carolina, a great volume of gneissoid and mica- 
ceous rocks similar to those of Ponylvcti succeeded to the 
west by (2nd.) the Ococee conglomerates and sandstones, with 
argillites, chloritic, taleose and micaceous slates, and occasiona 
ands of limestone, all dipping, like the rocks of the Ist division, 
to the SE. In the 8d place we have the Chilhowee sandstones 
and shales, several thousand feet in thickness, including near 
the summit beds of sandstone with Scolithus, and considered by 
petabicdees to slates and etal ban magnesian lime- 
stone; second, a group of many hundred feet of soft brownish, 
greenish, and buff shales, with beds of blue oolitic¢ limestone, 
which as well as the shales, contain trilobites. Passing upward 
these limestones become interstratified with the third sub-divis- 
ion, consisting of heavy bedded magnesian limestone, more or 
less sparry and cherty near the summit. The limestones of 
Knoxville belong to this group, which with the 3d or Chilhowee 
group is designated by Mr. Safford as Cambrian, corresponding 
to the Primal and Auroral of Rogers, or to the Potsdam or Cal- 
ciferous dandtocle, with the possible addition of the Chazy, being 
Fe tat obi S si great Magnesian limestone series of Prof. Swal- 
w of Miss To these strata succeed Safford’s 5th forma- 
tdi Sonnsiating pod limestones, the equivalents of the Black River, 
Trenton and higher portions of the Lower Silurian : 
n Eastern Canada we find a group of strata sinitae to those 
described by Rogers sat Safford, Be lala Spine ld» Sir Wit 
am Logan as the Quebec group. It has for its ae 
binek aid blue shales, soften pili roofing slates, succeeded ed 
grey sandstones and great beds of conglomerate, with Gittins 
and pure limestones, often oe arr meet and having the charac- 
ter of travertines, ‘These are associated with beds of fossiliferous 
Kee, and with slates conning compound graptolites, and 
R, Sct.—Szconp Seems, VoL. XXXI, No. 93.—May, 1861 
52 
