Bilger's rocks is a geological wonder, Surrounded by an
enchanting forest of fauna and flora. It is open to the public on a
year around basis and maintained by a non-profit group of
volunteers. It is a unique and permanent attraction that affords a
quality and inexpensive adventure in the great outdoors. If you and
others are about natural discovery and mystery, self-designed to
meet your exploration cares and needs across a variety of
disciplines, geology, deep-time, earth science, history, wildlife,
nature walks, environmental inquiry research, and a mosaic of
recreation choices, then this might meet your, family, or group
needs for the unusual.
This is a great place to visit. Whether you just want to take a
peaceful walk in nature or you are deeply interested in the
geological side of things, Bilger's Rocks await you. This is one of
natures true wonders - it has been over 300 million years in the
making.
The beautiful walking paths intertwine among huge moss covered
sandstone blocks that average 20' to 25' thick. The house size
blocks are slowly creeping their way down off the mountain. This
will take hundreds of thousands of years. This is a classic example
of what's been called a "rock city."
Bilgers Rocks are part of the Homewood Sandstone Member
(Curwensville Formation, Pottsville Group, Pennsylvania age) The
“city” was formed by FROST WEDGING
Frost wedging is a form of mechanical weathering (that is,
weathering that involves physical, rather than chemical change).
Frost wedging is caused by the repeated freeze-thaw cycle of water
in extreme climates.
Most rocks have small cracks in them, called joints (or,
tectonic joints). When it rains, rainwater seeps into these joints.
As the day cools and temperatures at night drop below freezing, the
water inside the joints freezes.
As water freezes into ice, it expands. You can test this at home
-- simply fill a bottle halfway with water, and draw a line on the
bottle where the water level is. Put the bottle in a freezer (but
don't put a cap on it!). Come back a few hours later, after the
water is frozen. As the water froze, it expanded beyond the mark
you placed on the bottle.
The expanding ice places pressure on the joints in the rock.
Finally, when the pressure is too much, the joint expands. In some
cases, the rock will split, though this usually happens after
repeated freeze and thaws. As new water is added during the warmer
days, more ice is created at night, wedging the joints apart
further. Gravity then slowly moves the large slabs of rock down the
hillside. The cracks vary in width from several inches to as much
as 25 feet in width. Several cracks are up to 50' long.
This is a work in progress.
Visit the Bilgers Rocks Website
Bilgers Rocks
To claim credit for this Cache you must email the answer the
following questions. Please watch where you are walking so you
don’t step into one of these cracks. Do not post the answers in
your log or it will be deleted.
1. At N40.59.641- W078.35.557 measure the width of the crack.
Parking is available near these waypoints.
2. At N40.59.637- W078.35.536 measure the width of the
crack.
Additional, But Optional, requirement- post a picture of you and
or your group somewhere at Bilgers Rocks