Prophet's Rock Earthcache EarthCache
Prophet's Rock Earthcache
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Welcome to the Prophet’s Rock Earth Cache
We have all seen many large boulders as we hike through the woods on our caching adventures. Have you wondered how they got there? Have they broken off a larger ledge ? Are they the remains after the softer materials were eroded away ? Were they dropped from the sky by aliens? Could they have rolled down the hill ? Or left from a melting ice sheet like this one.
Approximately 20,000 years ago we entered a cold period. During this ice age, great glaciers moved south. Along the way they broke and scrapped much rock and earth. There was an ice sheet of over a mile thick covering this entire area.
Approximately 10.000 years ago, as we went through a global warming period the ice sheet melted, depositing the glacial debris. Much of the smaller debris was carried away by the melting ice. This large rock was simple left here on top of the hill. It is called a glacial erratic, carried from somewhere northeast of here by the ice sheet during the last ice age.
The Rock is an igneous rock type, formed from a solidified magma. It is primarily a grayish granite, quite typical in New England. There is an interesting seam or vein that runs through the entire boulder. It can be seen on both ends and the split surface. Sometime after its formation, the original granite split. Molten material of what looks like mica and quartz was forced into the split. This igneous rock grain structure is quite different from the original granite due to its temperature and pressure at solidification.
A second interesting feature of the rock is it is split in to two halves. Rock is a relatively brittle material. Now think back to last winter and how we had to chip and break up the ice which is also a brittle material. Now measure the old fracture surface and think how much force was required to split this rock. It must have been a lot.
This rock has some very interesting Hebron history, as listed on the sign board at the parking area and on cache CRC-Prophet’s Rock, GC16J95.
How to log this Earth Cache
E mail the answers to these questions.
1. You will need to do a little math here. Estimate* the combined size of both halves of Prophet’s Rock.
Knowing this type of rock weights about 165 pounds per cubic foot and the typical “Smart Car weights 1600 pounds; How many Smart Cars does it take to equal the weight of this rock.
2. I was impressed by the fact the rock was split into two halves and how large the split surface is. Estimate* the surface area at the rock split.
3. Look at the vein that goes through the rock. Compare its structure, size and shape of rock grains, to the structure of the original granite material. What’s different?
4. According to legend, what year did the wives call and meet their husbands at Prophet’s Rock.
5. Optional, Attach a photo to your log of you or your group in front of Prophet’s Rock.
* Either use a tape measure or estimate using your height and step, (a left-right-left step is about 5 foot for an adult).
Additional Hints
(No hints available.)
Treasures
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