The Giant's Kettles at Rocky Neck
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***Congratulations to Mrs. Sherlock Holmes for FTF!***At Rocky Neck State Park, located at 244 West Main St. (Rt 156), in East Lyme. Parking fee for Spring and Fall weekends and through the summer, but you can walk or bike in for free or drive in at other times.
Welcome to Rocky Neck, a popular park for swimming, fishing, hiking, biking, and, of course, geocaching.
This state park has some wonderful geological features; among them, two fine examples of "devil's kettles", or potholes, round holes carved out of the bedrock. Potholes are most often seen in areas of turbulent water, such as Chapman Falls at Devils Hopyard SP, the Bulls Bridge area of the Housatonic River, and Shelburne Falls in MA. It's a little unusual to see them along the shoreline, so let's find out how they came to be.
As you might guess, the potholes weren't created overnight. About 13,000 years ago a mile-thick glacier covered CT and all of New England. As it receded, the melting waters formed rushing streams and rivers, which carried many stones and pebbles left by the glacier. Sometimes, small stones (called "grinders") would find a crack in the bedrock and, though trapped, continued to move and swirl about, pushed by the force of the water, making these cavities wider and deeper over thousands of years; see illustrations 1 & 2 below. Careful observation of some potholes may reveal gouges on the inside walls due to uneven wear.
To demonstrate, place a small stone into a container and apply a jet of water using a faucet or hose. Note that the force of the water will cause the stone to move about, trying to escape its confined space.
Thus, this bedrock and the potholes were here long before the wide, sandy beach was formed, and its possible that a river flowed over this very spot thousands of years ago, perhaps from Lake Hitchcock, a long, narrow lake which filled the CT river valley from Rocky Hill up to the middle of New Hampshire. Or, lacking a river, constant wave action could have provided the force necessary to carve out the potholes. What do you think?
In order to take credit for this cache you must email me the answers to the following questions:
#1. Measure the diameter of the oblong pothole, near the top edge (if you don't have a measuring tool, use something else, such as a hiking pole, rope, etc. and mark it so you can measure it at home); is it closest to:
a. 15 inches
b. 30 inches
c. 45 inches
#2. Why do you think this pothole isn't as round as its neighbor? (any reasonable answer will be accepted)
#3. The bedrock you are standing on is gneiss (nice), a fairly common, hard, metamorphic (heat and pressure) rock. Based on what you have learned, what conclusion can you draw about one characteristic, or property, of the small stones that carved out the potholes in the gneiss?
**Summer, 2013- I've heard a large rock has been deposited in the hole by Hurricane Sandy, so do your best with the measurement.
You may post your find online prior to emailing, but I reserve the right to remove logs with inadequate or incorrect answers. Photos can no longer be used for proof of visiting, but are welcomed and encouraged. If you would like to see a really big pothole, visit Archbald Pothole State Park in northeastern Pennsylvania, where the pothole is 38 feet deep and 42 feet wide! Enjoy Rocky Neck anytime of the year!
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