TACONIC QUESTION IN GEOLOGY. 289 
laid by more than 1,700 feet of argillites and sandstones, with intercalated strata of unctuous 
lustrous schists, apparently containing hydrous micas, and sometimes decaying to kaolin. 
In the lower portions, which become more quartzose, are beds holding in a slaty matrix, 
pebbles of quartz and of feldspathic rocks ; and the base of the section is described as a con- 
glomerate, made up of pebbles from the eozoic rocks of the Blue Ridge, towards which the 
whole series dips, and beneath which it seems to pass. The strike of the Primal rocks is 
N.60° E., while that of the eozoic is N. 30° E. The lower portions of the series are some- 
times concealed by faults. 
§ 57. It is hardly necessary to repeat that the great Lower Taconic belt, as above defined, 
includes the Primal and the Auroral, together with a portion of the Matinal of Rogers in 
Pennsylvania; where some localities were examined and described by Emmons. In our 
account of these rocks in that state, in the last chapter, we called attention to the thinning- 
out of the slates and quartzites in some localities along the borders of the deposit, and even 
their concealment beneath the conformably overlapping limestone. We also noticed the 
appearance of these rocks of the Primal division, elsewhere, from beneath the limestones, 
with a volume not less than that measured by Emmons and Fontaine. The great thickness 
assigned to the limestones of the series in Pennsylvania, is to be noted ; and also the consid- 
eration that some of this apparent thickness of several thousand feet may possibly be due to 
repetitions. We have also remarked the fact that these Lower Taconic or Auroral limestones, 
are brought up by undulations from beneath the overlying rocks in the central valleys or 
coves of Pennsylvania. The same condition of things is met with in Alabama, where the 
Auroral limestones or marbles, with their underlying slates and quartzites, abounding in 
limonite, as shown by Eugene A. Smith, are exposed on the great axis which divides the 
coal-basins of the Black Warrior and the Cahaba; and are also brought to view by a dislo- 
cation and uplift along the southeastern edge of the latter basin.* 
§ 58. Lying to the eastward of the Lower Taconic belt of the Appalachian valley, and 
generally divided from it by the range of ancient crystalline rocks to which belong the 
South Mountain and the Blue Ridge, there are other areas of Lower Taconic strata found, at 
intervals, from Georgia to New Brunswick, often appearing as parallel interrupted belts ; 
the remains of a mantle of these rocks once widely-spread over the older crystalline strata 
of the Atlantic slope ; from which, after folding and faulting, they have been in great part 
removed by erosion. 
§ 59. One of these Taconic areas was, as long ago as 1817, defined and mapped by Maclure, 
who described it as “a transition belt ” extending from the Delaware to the Yadkin in North 
Carolina, having a breadth of from two to fifteen miles, and a general dip to the southeast. 
He pointed out its course from the Delaware, passing by Norristown, Lancaster, York and 
Hanover in Pennsylvania, and Frederickstown in Maryland, through Virginia; noted its 
passage beneath the mesozoic red sandstone, and its termination in Pilot Mountain, in Surry 
county, North Carolina. The rocks composing this belt were described by Maclure as con- 
sisting of granular quartzite, granular limestone or marble, and various slates.f Through 
the Lancaster valley, as already noticed, ($ 45) the Taconic rocks of this eastern belt are 
connected with those of the Appalachian valley. 

* See Hunt on Coal and Iron in Alabama; Proc. Amer. Inst. Min. Engineers, Feb., 1883. 
f Maclure, Observations on the Geology of the United States of America, with a Geological Map, &c., reprinted 
from the 1st vol. of the Trans. of the Amer. Philos. Soc., new series. Philadelphia: 1817 ; pp. 42, 43. 
