THE VIRTUAL GEOLOGIC
The Wissahickon Creek in northwest Philadelphia is a
beautiful natural laboratory for exploring geologic processes including
metamorphism, plate tectonics, and surficial geology. This field
guide is intended for the casual geologist, one with an interest rocks
and earth history but without formal training. I hope that you
will be able to use it to increase
your enjoyment of the park. Please feel free to contact me (
) with comments and questions.
The guide is divided in two sections. First is
a tour of the area between Valley Green Inn and Rex Ave. The
tours the area along forbidden drive near Bell's Mill Rd. Valley
can be approached from either Chestnut Hill (via Springfield Ave.) or
Andora (by Wise's Mill Rd.). Once you reach the Inn, go across
the creek and follow
the trail along the Wissahickon to the north. You can return
by retracing your steps or following Forbidden Drive back to the Inn.
the walk with stops to take between 1 and 2 hours.
topographic map of the area between Valley Green Inn and Rex Ave.
-- Wissahickon Schist
-- More Schist
STOP 3 -- Evidence for mountain
STOP3A -- Tributaries to the
Wissahickon Creek STOP
4 -- High temperature metamorphism and melting of the rock
STOP 5 -- Amphibolites and their importance to
-- More melting
STOP 7 --
Age relationships between schist and granite
STOP 8 --
Recent faulting along the Wissahickon
STOP 9 --
Erosion and deposition in the Wissahickon