346 The American Geologist. June, i89i 
chaean Protaxis." " From the base of the Cambrian beds, where 
they rest discordantly upon those of the Archaean Protaxis, the 
whole series of Lower- and Upper-Palaeozoic formations succeed 
each other in apparently conformable secpience, except at the 
junction of the Lower- and Upper-Silurian series, where a prob- 
able discordance occurs. Throughout the prolonged period dur- 
ing which these formations were being deposited, there was con- 
tinuous subsidence with occasional pauses, over the region tying 
to the west of the Archaean continental area, and successive for- 
mations of marine strata were laid down in vast sheets over the 
bed of the ocean, never very deep. In later Carboniferous times 
the marine deposits gave place to those of lacustrine or estuarine 
origin, but still without any apparent discordance in the strati- 
fication ; so that the Upper and Lower Carboniferous beds are 
apparently conformable to each other, and these again to the 
Devonian and Upper Silurian. " This sequence of conformability 
might just as well have been extended down into Lower Silurian 
horizons since no actual discordance was observed in Tennessee, 
and conditions noticed in New York and the New England states 
do not determine the presence or absence of breaks in the con- 
formability of strata in a neighboring state. Tennessee however 
is far distant. 
' ' The prolonged period of subsidence and deposition above de- 
scribed at length gave place to an epoch of elevation and con- 
traction of the crust, acting with greatest effect and intensity 
along the line of the Alleghanies, where the Pakeozic strata 
are folded, flexured, and even reversed along parallel axes 
The foldings of the strata, it is well known, generally subside in 
a westerly direction towards the valley of the Ohio, and ultimately 
pass into widely extended domeshaped centres of elevation with 
intervening areas of depression. Amongst the former are the 
"Cincinnati uplift" and the anticline of the Nashville Silurians : 
amongst the latter is the region of the Cumberland plateau, which 
lies along the centre of abroad sync-line. - ' It is evident from 
these remarks that Dr. Hull ascribes the formation of the Cincin- 
nati-Nashville anticlinal to post-Carboniferous times. At the 
close of this period of. folding eastern Tennessee could be termed 
a great valley, the lowest parts of which lay within the region of 
the present Cumberland plateau, and the boundaries of which 
