Lackawanna. -Area, 440 square miles; population in 1880, 89,269. This
county, recently cut off from Luzerne, is in its south-eastern half
a wilderness plateau of horizontal Pocono sandstone strata (X) 2000`
A.T., traversed by deep ravines of Catskill red rocks (IX) drained by
Spring brook, Roaring run, and other small streams, through gaps in
the Wyoming or Bald mountain into the valley of the Lackawanna river.
This valley is the Scranton-Carbondale anthracite coal basin, the upper
end of the great Northern Anthracite coal field entering the county
at its north-east corner and running south-west into Luzerne county,
with a length of 25 miles, and a width (of coal measures) of 2 miles
at its upper, and 3 miles at its lower end, but nearly four miles wide
at Scranton. Its north-western wall is the Shickshinny or Lackawanna
mountain of steeply dipping Pocono rocks (X), with a terrace of the
Conglomerate (XII) running along its face, beautifully sculptured into
a series of triangles by the drainage from the crest. Opposite Providence,
Blakely, and Carbondale the mountain is gapped by small streams. The
country behind it, constituting Benton, Abington, Greenfield, Scott,
Newton, and Ransom townships, is a wide and elevated anticlinal valley
of Catskill formation No. IX, mostly drained north-westward by the Tunkhannock
waters into the Susquehanna River in Wyoming County. This river forms
the western boundary for about seven miles, and affords good sections
of nearly horizontal Catskill and Pocono rocks, growing steeper down
stream, and standing in bold cliffs (Campbell’s ledge) in the gap at
Pittston. Here the lowest pebbly beds of the Conglomerate (57`) have
under them a remarkable black shale (5`) full of fossil plants (for
list see Report G7, pages 39-40) and six species of fossil
insects belonging to the genera Miamia, Haploplebum, Euphenierites,
Gereblattina, and Archymilacris.† Mr. Lacoe of Pittston,
whose magnificent collections furnished a large contribution to Mr.
Lesquereux’s Coal Flora (Report P,) found Spirorbis carbonarius shells
attached to many of the plants, and obtained also a few poorly preserved
shells from the lower layers of shale. Beneath the shale lies a 3` sandstone,
and then 150` of Mauch Chunk flagstone layers and greenish sandy shales,
without a trace of the usual red shale of XI. The Pocono No. X here
measures 353`, with massive gray sandstone at the top (100`); at the
bottom, a beautifully ripple-marked massive gray sandstone (30`) having
very large quartz pebbles at its base, lying on 100` of soft green shale;
and 55` above it the white Griswold Gap conglomerate (45`,) the
upper layers of which have been extensively quarried in Ransom township
for public buildings. Alternations of X and IX (300`) underlie it, beneath
these 1231` of typical Catskill (IX) have been measured along the river
down to the crown of the arch, near the west corner of Ransom township.
The Lackawanna Coal basin holds only 307` of coal measures, with a total
of 20` of coal, at its north-east end; 282` of measures, with 13` of
coal, at Carbondale; 633` of measures with 67` of coal, at Scranton;
and 816` of measures, with 85` of coal, further west. * The floor of
the great trough rolls so as to sub-divide it into several sub-basins.
The rolls issue from the south-east side, and run diagonally westward,
dying out against the north-west side. Twenty-one collieries are at
work in the Carbondale mine inspector’s district, producing in 1873,
1,738,853 tons. Forty collieries in the Scranton district produced in
1883, 4,725,315 tons. The north part of the Pittston district lies in
this county. For details of these collieries, see Summary Tables on
Sheet Plate VI of Second Report of Progress (AA.) The whole of this
county is covered with glacial drift, and the surface of rocks are scratched
by ice, which must have been at least 2000` thick to pass over the valley
and cover the great highlands to the south of it; but the drift in the
valley itself is made up mostly of native fragments, very few pieces
from New York or New England being observed.
Described by Mr. Scudder in his "Palaeozoic Cockroaches," Boston
Soc. Nat. History, Vol. VIII.
* See Report AA, p.222 to 226.
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.
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