At the turn of the 20th Century, the B&O Railroad ran along the
Cassleman River, cutting through and exposing millions of years of
geologic history. By the turn of the 21st Century, the railroad was
gone and the throughway had been converted to bike trail.
Geologists from the Bureau of Topographic and Geologic Survey, the
DCNR, the Somerset County Rails to Trails Association and local
educators developed a K-12 geology course plan for the 7 miles of
trail between Rockwood and Garrett.
From Rails
to Trails to Rocks: Student Trail Guide
Accessing the Trail
The objective of this cache is
approximately midway between Rockwood and Garret so you can
begin from either end. From Somerset, follow the "BicyclePA
Route S" signs south on SR3015. At Route 653, turn right if
you want to go to Rockwood or left to go to Garrett. The
parking area at Rockwood (N39 54.653' W79 9.653') has a water
fountain and a portajohn, Garret has two parking areas (off
Rt2037 at N39 51.631' W79 3.784' and at Brandt Landing on
Water Works Road at N39 51.897' W79 3.897'). The trail to the
cache site is a fine crushed limestone and is quite level. One
could easily walk from either parking area to the cache site
and back in a matter of hours but a bicycle is recommended,
allowing you to get to the cache site in 20 minutes.
Wymps Gap Fossil Quarry - F-GR5 (N39 53.281 W79
7.394)
During the Mississippian Period about 330 Million Years ago Western
Pennsylvania was the shore of a shallow sea. The exposed limestone
layers are a fairly thin band of fossil bearing rock sandwiched
between layers of shale.
Unlike other EarthCaches, feel free to bring a rock hammer and
dig for fossils. The Rockwood Borough Water Authority periodically
comes through with a backhoe to expose more layers of rocks for
easy access by students on geology field trips. The bulk of the
fossils seem to be brachiopods but fossil hunters have found
crinoids and trilobites.
Common
Fossils of Pennsylvania
DCNR
Fossil Plates
| To log this find, you need to post a
description of at least one fossil you found. Check the fossil
links above to identify it. (You'll be able to identify the Phyllum
easily, class, genus and species will be increasingly difficult. Do
your best.) Describe it's size. It's features. You know; science
stuff. Some fossils are more common than others. Try to find
something uncommon. (I want to see a trilobite.) Post pictures if
you can get them. |
But wait, there's more!
There are many other posts along the trail, each pointing out
another geologic interest.
Pottsville Sandstone Boulders - M-GR1 (N39 52.182 W79
4.082)
The rocks making up these boulders formed about 310 Million years
ago during the Pennsylvanian Period. At the time, the Appalachian
Mountains were granite monsters, higher than the Himilayas are
today. Erosion washed the mountains into the shallow sea that once
was here where the granite bonded in the silica-rich waters to form
a very strong 200 ft thick layer. 100 Million years later, the
Alleghenian orogeny created a new mountain range on the grave of
the old. The harder Pottstown survived the weathering much better
than the softer surrounding stone. These particular boulders broke
free of the layer during the last ice age and from 24,000 to 18,000
years ago had been working their way down the slope.
Missippian Mauch Chunk Formation - K-GR2 (N39 52.276 W79
4.640)
Several hundered feet below the Pottsville Sandstones are thinly
layered, olive-grey siltstones, sandstones and limestones, or
reddish-brown silty claystones. Something else you will notice is
the disappearance of Rhododendrons. These plants flourish in the
acidic soils derived from the Allegheny Formation, Pottstown
limestones and the upper parts of the Mauch Chunk Formations. But
the lower parts of the Mauch Chunk are more alkaline and the
Rhododendrons don't do so well here.
Cassleman River Gorge Landslide - L-GR2A (N39 52.500 W79
5.099)
A "colony" of Rhododendron marks the location of an ancient
landslide that brought Pottsville Limestone and upper Mauch Chunk
Formation down from over 300 feet up the hillside some 10,000 years
ago.
Festooned Crossbedding - I-GR3 (N39 52.795 W79 5.603)
The thick grey sandy limestone is known as the Loyalhanna Member of
the Mauch Chunk Formation. The ripples are essentially petrified
sand dunes and the abrupt changes in directions were caused by
weather differences, the wind blowing the waves in another
direction, re-aligning the sand beneath the waves.
Anticlinal Axis - H-GR4 (N39 52.700 W79 6.363)
200 Million years ago when North America ran into Africa, what is
now the east coast folded up like an accordion, (The Alleghenian
orogeny) creating the current generation of the Allegheny
Mountains. This point would mark the high point of the Negro
Mountain fold along the trail except that Lick Run has eroded away
the hundreds of feet of rock to reveal the oldest rock along this
section of trail. You'll see that the layers of the Burgoon
Sandstone in the creek bed lie horizontally.
Burgoon Sandstone - G - (N39 52.779 W79 6.803)
Another stream bed that has cut down to expose the oldest layers
along the trail. While it is difficult to see, it's not as far off
the trail to see these stones.
Mauch Chunk Formation - E - (N39 53.357 W79 7.465)
Off the trail is a section of the Mauch Chunk Formation that sits
just above the Wymps Gap Limestone layer.
Pottsville Limestone - D-GR6 (N39 54.280 W79 8.459)
The curve of the anticline brings the bed of the Homewood Formation
of the Pottsville Limestone and the associated rhododendrons back
down to trail level. Fossil Sigillaria, large scaly trees, can be
found in the lower layers of this bed.
Gob Pile - C-GR7 (N39 54.735 W79 9.041)
The large pile of dark material is waste rock produced during
mining on the Lower Kittanning coal seam.
Penelec Mine #3 - B-GR8 (N39 54.727 W79 9.229)
The rusty-colored stream is polluted mine runoff. AMD or Acid Mine
Drainage is caused by water and oxygen reacting with pyrite exposed
during the mining process. The acidic content of the water is
similar to that of lemon juice.
Lower Kittanning Coal Seam- A-GR9 (N39 54.698 W79
9.475)
Some 300 Million years ago, Pennsylvania was much further south
than it is now, almost at the equator. This whole region was a
costal-plain delta with peat swamps. These thick layers of peat
were covered and compressed into this fairly narrow layer of coal.
Even though it was difficult to mine, the Industrial Revolution's
appetite for coal pushed miners to work this seam in spaces no
higher than that under your desk.