Geology: This outcrop is an erosional remant of an igneous rock
called diabase. During the Jurassic period in southeastern
Pennsylvania, a large mass of molten rock cut upward into Triassic
sedimentary rocks. Subsequent erosion of rocks allowed these
resistant rocks to form some of the highlands of the piedmont. The
diabase is composed mostly of minerals plagioclase feldspar and
pyroxene. Crystals of plagioclase are enclosed with pyroxene
crystals, which give it a texture called "ophitic." The boulders
are spheroidally weathered.
A profile of the rocks from the north or south reveals a form
that gives the outcrop its name—"Dinosaur Rock."
The outcrop is said to date from the Triassic Period, 208-245
million years ago, when the first dinosaurs appeared on Earth.
Site is potentially threatened, especially by graffiti.
NO access from the PA turnpike, park at the State Gamelands 241
parking area just across the road from the trail to Dinosaur Rock.
( Here are the coords for the parking area across the road from
"Dinosaur Rock... N40 13.780 W076 30.250)
Follow the trail about 500 feet to the diabase rocks. Easy
walking though cars travel fast along Route 241, which must be
crossed from the parking area. Path is fairly smooth and flat but
may be rough for a wheelchair. Rocks may be slippery; climbing is
not recommended.
TO CLAIM A "FIND", E-MAIL (DO NOT LIST ON THIS SITE) THE ANSWERS
TO THE FOLLOWING 4 QUESTIONS.
1. What does the "ophitic" texture tell us?
2. What likely caused the spheroidally weathered boulders?
3. What is the heritage value of this site?
4. Estimate the height of the diabase remnant.