Indian Rock Shelters EarthCache
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Welcome to the Indian Rock Shelters in Madison, CT. This adventure consists of a 1.2 mile loop hike with the exploration of geologic features. This land is owned and maintained by the Madison Land Conservation Trust (www.madisonlandtrust.org)
Getting There: From the North Madison traffic circle (intersection of Routes 79 and 80), go east on Route 80. Go 0.7 mile, then take a left onto Summer Hill Road. Go another 0.7 miles, then take a left onto Twilight Drive. Turn onto Lake Drive and follow to the end. Parking is available in the cul-de-sac where you will find the trailhead.
Be Prepared: Bring a measuring tape and proper footwear. There are some wet spots and some optional climbing.
The ridge that dominates this hike is made up of a granitic igneous intrusion. The rock formed when magma slowly cooled below the surface and formed a granitic pluton. (Pluto being the Roman god of the underworld.) Dialing back the calendar approximately 550 million years, you find yourself standing at the edge of the Iapetos Ocean, the precursor to the Atlantic Ocean. Approximately 300 million years ago, the Iapetos Ocean was squeezed, probably by the collision of tectonic plates. The collision and ensuing heat and pressure caused the metamorphism of the granitic pluton. After millions of years of erosion, we now see the Monson Gneiss (pronounced “nice”) exposed.
Gneiss is a metamorphic rock, which means it formed at great depth where pressures and temperatures were high. As the rock reaches the surface due to erosion, the pressure is released and the rock tends to break in many places. Glacial ice flowing over the rocks moved some of them. They became rounded off and were deposited elsewhere by the glacial ice between 24,000 and 16,000 years ago. These glacial erratics can be found in many places in Connecticut and most are also Monson Gneiss.
The diverse forest here contains beech, red and sugar maples, red, black, white ash and hickory. The stream at the north part of the property flows northward into the Hammonassett River watershed. Just to the south, the watershed drains into the headwaters of the Neck River.
Follow the blue blazed trail north. The trail passes just to the left of a stone wall which is the western boundary of the Southern Regional Water Authority land. The trail eventually doubles back and heads south, along the rocky ridge. At the published coordinates you will find the first of two Indian rock shelters. During the winter, this was a good shelter for Indian families.
Question Number 1: Inside the rock shelter there is a thin layer of light-colored granite. What is the thickness of this thin layer at the thickest and thinnest points? This banding in the rocks was caused by the concentration of different minerals into layers during metamorphism. How do you think the shelter formed? (Think about the difference between the “roof” and the “floor” as well as natural forces)
Head south on the trail. You may see a few vernal pools, great habitat for frogs and salamanders. Next, you will come to the second rock shelter at N 41’ 22.321 W 072’ 38.091’
Question Number 2: The floor of this shelter is made up of the hard light-colored granite. Measure this layer at its thickest and thinnest points. If you like, climb up into the shelter and look out. Give three reasons why this would make a good winter shelter.
Continue on, cross the bridge over the Neck River and there is a small spur trail to a view of Bartlett Pond. N 41’22.329’ W 072’ 37.976. A short distance later, you are back at the parking area.
Logging Instructions: E-mail the answers to Questions 1 and 2 above, then immediately log. Also, post a photo of one of the shelters! Don’t forget to check out information regarding becoming an Earthcache Master found at www.earthcache.org
Sources: Madison’s Trails, Madison Land Conservation Trust
The Geology of Chatfield Hollow State Park, CT DEP
Great Day Trips to Discover the Geology of Connecticut!, Greg McHone
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