Thunder Rocks II EarthCache
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Thunder Rocks is located in the beautiful 65,000 acre Allegany State Park. Depending on time/season there maybe an entry fee to the park. Non-park campers are requested to limit visits between dawn and 10 PM.
This cache has been given permission to be permitted within Allegany Region Permit #ALL240
A Place of Legend
An Iroquois legend describes a struggle among the guardian spirits of rocks to determine which one could throw the biggest rock to the top of this mountain. A nearby Iroquois tribe, after hearing the thunderous noises resulting from the contest, set out for the mountaintop where they discovered these rocks, which they named “Thunder Rocks.”
How Thunder Rocks Was Formed
Thunder Rocks are sedimentary rocks of Olean conglomerate, which is made up of layers of coarse sand and white, rounded quartzite pebbles. This is a mixture which when exposed to the elements, is rather easily degraded.
During most of the Paleozoic era, a shallow saltwater sea covered this area. Near the end of the Devonian period, a collision took place between North America and another landmass. As a result, a range of mountains, called the Acadians, was created. Time passed and erosion from rivers deposited gravel in the area.
A later collision of continents formed the Allegheny Mountains to the southeast, but raised western New York and north central Pennsylvania into a high plateau. Erosion of the plateau took place throughout the entire Mesozoic era, the age of dinosaurs. New York State was worn down to a peneplain, a flat land area near sea level.
Sixty-five million years ago the peneplain was elevated, forming the modern day Allegheny Plateau. Subsequent erosion resulted in the development of deep valleys and uncovered the ancient Paleozoic rocks. The youngest of these, including Thunder Rocks, are found on the highest hills in the park. Older Devonian rocks are exposed in the valley walls. The glacial ice did not transport Thunder Rocks here. Thunder Rocks are native bedrock and remain where they were deposited as sediments 325 million years ago.
The large boulders will eventually break up. Water will enter the vertical cracks, called joints, and horizontal cracks, which are called bedding planes. Water expands when it freezes, causing ice wedging. Tree roots growing in cracks like these also break rocks apart in time. Other factors that contribute to the spaces between these rocks is what is called “soil creep”, when the rocks start to slide slightly downhill resulting in a drifting apart of the larger portions. Often this downhill is very slight. The resulting “laneways” create the impression of “Rock Cities”.
This Earthcache will take you to this formation in Allegany State Park. Spend some time wandering in the areas between these Devonian rocks, which range in size from soccer ball size to as large as houses.
To claim this cache:
You will need to locate one of the named formations which start (You may choose other rock formations there also, this is just a start point) at: N42 02.502 W078 42.074
Estimate the size of this formation in its circumference.
Speculate on the causes of erosion as it appears on this formation.
Take a photo of yourself and/OR your GPS in front of this formation.
PLEASE email your answers to me via groundspeak within 48 hrs or as your log will be deleted.
Additional Hints
(No hints available.)