Centre. - Area, 1230 square miles; population in 1880,
37,922. This large and important county presents all the most interesting
features of the Palaeozoic geology of the State on a grand scale-
a wide expanse of mountain upland, with important coal areas on its
top, in the western townships- an uninterrupted Devonian and Silurian
valley crossing its middle townships- great anticlinal waves bringing
up to the present surface hundreds of square miles of Siluro-Cambrian
magnesian limestones, charged with superb deposits of brown hematite
iron ore-long parallel symmetrical synclinal ranges of Medina-Oneida
mountains separating the limestone valleys- and a labyrinth of these
mountains in the south-eastern townships, formed by numerous close
rock-waves and faulted in several places. Most of the Allegheny mountain
plateau has been denuded of its former covering of coal measures;
but considerable minable areas of them are preserved along the center
line of the First Bituminous basin, viz: a continuous belt 2 or 3
miles wide and 16 miles long, along the Moshannon river in Rush township;
another 3 miles wide by 9 miles long, around Snowshoe, Moshannon,
Pine Glen, and Germania, stretching west to the Susquehanna river;
and seventeen other smaller patches along the headwaters of Beech
creek, and on Hays run, along the Burnside-Snowshoe township line,
and in Curtain township. The Snowshoe coal beds, first mined in the
early part of the century, are now extensively worked. The Freeport
upper coal, 5' thick, caps the highest knobs, Askey hill, &c.,
covered with the last remaining blocks of the great Mahoning sandstone.
The Freeport lower coal, so important at Karthaus, is thin in Centre
County. The Kittanning upper coal is the bed of the region, from 5
to 7 feet thick, in three benches, with a coarse cannel roof. Numerous
small downthrow faults are met in the mines. Analyses show 70 per
cent carbon, 25 gas, 3 ash, 1 sulphur, less than 1 water, and good
coke is made of it. Four other beds, 3' or 4' thick, exist; and several
limestone beds, one if which, the Freeport lower limestone, is the
key-rock of the district, from which all measurements are made and
the coal beds are identified. The Pottsville conglomerate, XII, 250'
thick, makes the crest of the Allegheny mountain * and the rocky sides
innumerable ravines. Under it the Mauch Chunk red shale, XI, 150'
thick, appears; and is also brought up in the bed of the Susquehanna,
below Salt Lick, at the west end of Burnside township, and along both
sides of Beech Creek valley, in Curtin township, everywhere topped
by a plate of carbonate of iron, "the red ore bed," of variable thickness,
never exceeding 4'. The Pocono sandstone, X, is more than 600' thick,
and forms a bold, straight, forest-covered ridge of coarse, and often
conglomerate white sandstone, covered with bowlders, and keeping a
pretty regular height of 2200' A.T. The Catskill rocks, IX, form a
broad, flat terrace in front of the Allegheny mountain its whole length,
which can be well studied in Worth township, where the old turnpike
to Philipsburg runs along it; they are 2600' thick. The Chemung and
Hamilton formations form the foot hills, and the Marcellus dark shales
(800') the bottom of the Bald Eagle valley; in all more than 6000'
thick of middle and lower Devonian measures, rising from beneath the
Coal regions at increasing angles from 100 to 600.
The astonishing straightness of the Bald Eagle valley (N. 450
E.) across the county is explained by the vertical attitude of the
rocks of the Bald Eagle mountain, at the west foot of which runs the
low ridge of Oriskany sandstone VII, and Lower Helderberg limestone
VI. At the Clinton county line VII is 130' thick, but thins southward
to nothing a few miles south of Milesburg, and has been seen after
that at only one place; it furnishes inexhaustible quantities of the
finest glass sand, is excessively fossiliferous, but seems to offer
no iron ore. The limestone VI is finely developed in Centre County,
1020' thick, and has been quarried in the neighborhood of the charcoal
iron furnaces. It is both argillaceous and cherty, and, as usual,
quite fossiliferous. No. V (Onondaga and Clinton) 1040' thick, makes
the west slope of Bald Eagle Mountain, but its fossil ore beds are
scarcely recognizable; one thin layer was formerly mined a little
at Howard. "Paint Springs" issue from its outcrop. The Bald Eagle
mountain rocks stand vertical; the west crest made by Medina white
sandstone (938',) the east crest by Oneida white sandstone (710',)
and the interval by Medina red rocks (774',) in all 2425 feet thick,
containing neither useful minerals nor any fossils, except a few casts
of a sea weed called Arthrophycus harlani. This triple formation
(IV) makes all the other mountains of the county: Nittany, Brush,
Penns, Tussey, and Seven mountains; but as their dips are not vertical,
their crests are made by the upper (Medina) division, while bold and
beautiful terraces are made by the lower (Oneida), cut into short
lengths by innumerable ravines heading in the softer outcrops of the
middle division. No.III, Loraine (Hudson River) and Utica slates,
1000' thick, make the foot slope of the terrace, and in front of it
spreads the fertile but waterless rolling plain of the great valley
limestone formation No. II (at least 6000' thick) the bottom of which
is nowhere to be seen. Innumerable caverns lie concealed, through
which flow streams, fed through sink-holes in the surface. One of
these caverns is the channel-way for a considerable stream which sinks
in Brush valley and rises in a great spring in Nittany valley, passing
beneath Nittany Mountain at a depth of at least 4000 feet. Another
sinks into a cave near the end of Brush Mountain, and rises in the
"Fathomless spring" as Penn's creek. Big Hollow, along which the Bellefonte
and Buffalo Run railroad runs, is the floor of an ancient cavern five
miles long, the roof of which has been long since carried away, and
sink holes along its course show that a new cavern has been found
beneath it. Caverns filled with iron ore, on Sinking creek near Egg
Hill in Potter Township, prove that the great brown hematite pipe
ore deposits of Centre county fill depressions in the limestone which
were once roofed like other caverns. Of these immense ore beds the
largest and most famous is that of Pennsylvania furnace, in the southern
corner of the county, the open excavations extending 1500 feet in
length by 500' wide and 60' deep, the ore being known to be 30' or
40' deeper. Seven groups of these deposits, embracing more than fifty
banks, are described by Mr. d' Invilliers, in Report T4.
* 2236' A.T. at middle summit; 2281' northern summit
Three Springs at head of Moshannon; 2614' highest ground one mile
further east; 2043 at railroad grade at Emig's gap; 1735' in the notch
where the Snowshoe R.R. crosses it; level of Snowshoe 1572'.
From: A geological hand atlas of the sixty-seven
counties of Pennsylvania :embodying the results of the field work
of the survey, from 1874 to 1884. By J. P. Lesley. (Report of
progress (Geological Survey of Pennsylvania), v. X ) Harrisburg, PA
: Board of commissioners for the second geological survey, 1885.
Return to Geologic
Maps of Pennsylvania Counties
Copyright © 2000, Pennsylvania State University
Libraries. All rights reserved.
Please send comments to: ems@psulias.psu.edu
Last modified: 5/3/01
