PIONEER TUNNEL
COAL MINE
Pioneer Tunnel in Ashland,
Pennsylvania is a tourist site that allows examination of an old anthracite
strip mine and underground anthracite coal workings in Mahanoy Mountain.
The surface strip mine and the underground mine exploited anthracite coal beds
in the Llewellyn Formation (middle Desmoinesian Series, upper Middle
Pennsylvanian), as did numerous mines in eastern Pennsylvania's coal fields.
Mammoth Vein Stripping - partially overgrown
surface strip mine on Mahanoy Mountain that exploited the northward-dipping
Mammoth Coal bed (lower Llewellyn Formation, Desmoinesian Stage, upper Middle
Pennsylvanian). Looking WSW.
Ashland Mountain, looking E. This
ridge is a continuation of the Mahanoy Mountain ridge (behind the
camera). The gap in the foreground is where Mahanoy Creek lies.
Northward-dipping rocks of the Llewellyn Formation make up most of both the
Ashland Mt. & Mahanoy Mt. ridges.
Mahanoy Mountain cross-section, looking W,
showing steeply tilted, northward-dipping rocks of the Llewellyn
Formation. This is the southern limb of the Shamokin Syncline. The
surface strip mines exploited the thickest anthracite beds in the section - the
Mammoth Coal (left) and the Primrose Coal (right). The
underground mine principally exploited the Orchard, Primrose, Mammoth, Seven
Foot, and Buck Mountain Coals. The yellowish-colored beds on the
cross-section are supposed to indicate siliciclastic rocks (shales, siltstones,
sandstones).
Pioneer Tunnel - modern tourist entrance
to old Pioneer Tunnel Coal Mine, which operated from the 1910s to the
1930s. Anthracite coal was hauled out by rail to the eastern end of
Mahanoy Mountain, where it was dumped down a chute to a breaker for processing
and shipping.
Pioneer Tunnel Coal Mine, looking S - near southern
end of main tunnel, at the top of the Pottsville Formation, just below the base
of the Llewellyn Formation. The Little Buck Mountain Coal bed is
indicated by the small white sign. It is the top-most coal bed in the
Pottsville. Near the end of this mine's commercial activities, a tunnel
was driven further south & a gangway was developed along the Lykens Valley
No. 1 Coal in the Pottsville Formation's Schuylkill Member (upper Atokan
Series, lower Middle Pennsylvanian). The Lykens Coal was the
stratigraphically deepest unit exploited here.
Pioneer Tunnel Coal Mine, looking W. This is
the Buck Mountain Gangway, developed along strike at the Buck Mountain Coal
bed, at the very base of the Llewellyn Formation. The rock wall hanging
over the tourists' heads at upper right is the upper bedding plane of the
mined-out Buck Mountain Coal. The tilt of this bedding plane is
representative of the dip angle of all the rocks in this mine.
Mammoth Coal, looking E - northward
dipping (tilted to the left) anthracite coal of the Mammoth Coal bed, in the
lower Llewellyn Formation. The Mammoth is the thickest anthracite bed in
the entire world. It has been extensively mined throughout eastern
Pennsylvania's anthracite coal fields. At many localities, it is a
succession of three separate coal beds (three “splits” - Bottom Split, Middle
Split, and Upper Split), separated by fine-grained to coarse-grained
siliciclastics. Where the Mammoth Coal is one unit, it can be up to 50'
thick. Structural doubling & tectonic flow can make the Mammoth Coal
appear even thicker in some places.
Mammoth Coal - anthracite coal sample
(12.4 cm across) from the Mammoth Coal bed. Collected from exposure shown
above, along the walls of the main tunnel. Collected & generously
donated by Pioneer Tunnel Coal Mine staff.
Anthracite Coal - large block on public
display at Pioneer Tunnel Coal Mine.
Anthracite Coal - large block on public
display at Pioneer Tunnel Coal Mine. This material is ~90% carbon.
Anthracite Coal - large block on public
display at Pioneer Tunnel Coal Mine.
Fossil log (probably a tree fern,
either permineralized or a cast) in basal siliciclastic beds of the Llewellyn
Formation (upper Middle Pennsylvanian). It's exposed in the hanging wall
of the Buck Mountain Gangway.
Fossil logs (carbonized compressions)
in basal siliciclastic beds of the Llewellyn Formation. Hanging wall
exposure along the the Buck Mountain Gangway.
Fossil lycopod log (carbonized compression) in
basal siliciclastics of the Llewellyn Formation. Hanging wall exposure
along the Buck Mountain Gangway.
Fossil tree trunk (preserved as a cast) from
the Llewellyn Formation at Pioneer Tunnel Coal Mine.
Some info. from:
Ermert, E.R.
1994. The Story of Pioneer Tunnel Coal Mine & Steam Train.
14 pp.
Edmunds, W.E., V.W. Skema
& N.K. Flint. 1999. Stratigraphy and sedimentary tectonics,
Pennsylvanian. in The geology of Pennsylvania. Pennsylvania
Geological Survey Special Publication 1: 148-169.