Metamorphic Folding EarthCache
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This is a tough mountain hike; know your physical limitations. You will hike 4 miles round trip over steep and rocky terrain climbing 2,000ft to the summit. Do not attempt in poor weather unless you are an experienced hiker. Leave no trace behind
Attention: abide by park rules for your safety and respect of the mountain and be prepared for inclement weather while on hike. Although Monadnock is a challenging hike it is frequently visited each year by over 100,000 hikers.
Monadnock is said to be the second most frequently climbed mountain in the world, after Japan's Mt. Fuji. It is a hiker friendly park. The park is open year round but unless you have hiking experience in extreme weather hiking in winter is not recommended. Wear broken-in boots, bring plenty of water in plastic containers, have rain gear packed, dress in layers and stay on marked trails. For more information on the park go to (visit link)
Begin your hike from the state park headquarters located at the entrance to the park. The park is located in Jaffery, NH not far from route 124. Hike the white dot trail to the summit. Once you are at the summit continue to follow the white dot trail towards the northwest and begin to descend from the summit. Look for signs for the White Arrow trail. Billings Fold can be seen from the White Arrow trail looking back up towards the summit. The fold is north of the White Arrow Trail. Make your way over to the fold from either the White Dot trail or the White Arrow trail. Just in front of the fold there is a large rock that juts up and out. It creates a v-shaped draw. This is a good place to protect you from the wind and eat lunch. Observe the fold from this area and annotate your findings so that you can get credit for the cache. The elevation of the observation site is approximately 3,110ft ASL.
Monadnock is a representation for much of the geological history in New England. History shows that Monadnock’s birth occurred in the Devonian period about four hundred million years ago. At that time an ocean covered the entire region. Eventually the water receded and left behind flat land, flat as a table. At that time the land was made up of mostly sand and clays.
After a few hundred million more years the surrounding land began to fold up. This occurred simultaneously with the folding of the Appalachian Mountains. As this land folded the layers of sand and clays came under intense pressure and heat. In fact it is believed that the core of these layers that folded is Mount Monadnock. The layers of sedimentary rock metamorphosed into metamorphic rock called quartzite and schist. Geologic history shows that Mount Monadnock’s rocky top was probably formed some nine miles below the surface. Monadnock schist in particular can be seen in Billings’s fold, the fold you are observing. The schist is a conglomerate of minerals called mica, garnet, tourmaline, and sillimanite.
As you observe the fold you will notice a white, solid, 12 inch layer of rock running horizontally from left to right. This rock occurred after the folding ended. It boiled its way up through the schist as molten magma and is younger rock than the schist.
The reason that you can observe Billings Metamorphic Fold today is due to glacial activity in the region. A glacier is one of the most powerful agents of erosion. Glaciers erode by plucking away at rocks and sediment beneath it. The glacier carried away much of ground that previously covered the mountain and exposed the folded metamorphic rock you are observing.
Classification of Folds:
Folds can be classified based on their appearance.
• If the two limbs of the fold dip away for the axis with the same angle, the fold is said to be a symmetrical fold.
• If the limbs dip at different angles, the folds are said to be asymmetrical folds.
• If the compress ional stresses that cause the folding are intense, the fold can close up and have limbs that are parallel to each other. Such a fold is called an isonclinal fold
• If the folding is so intense that the strata on one limb of the fold becomes nearly upside down, the fold is called an overturned fold.
• An overturned fold with an axial plane that is nearly horizontal is called a recumbent fold.
• A fold that has no curvature in its hinge and straight-sided limbs that form a zigzag pattern is called a chevron fold.
Igneous Intrusions:
• Igneous intrusions are younger than the rock surrounding it.
• Igneous intrusions that are vertically inclined are called Dykes. Igneous intrusions that are horizontally inclined are called sills.
In order to get credit for this cache you must do the following:
1. Which direction (a magnetic azimuth please) does the apex of the fold point?
2. What is the geologic name for this kind of fold?
3. What is the geologic name for the intrusion of rock that you can observe?
4. Look at the broken rocks at the bottom of the fold; explain how they got there and how they broke up. Answers may vary.
5. E-mail your findings.
Visiting this cache site accomplishes several Massachusetts’ required teaching standards in Science and Technology.
Massachusetts Frameworks:
• Give examples of how the surface of the earth changes due to slow processes such as erosion and weathering, and rapid processes such as landslides, volcanic eruptions, and earthquakes.
• Describe and give examples of ways in which the earth’s surface is built up and torn down by natural processes, including deposition of sediments, rock formation, erosion, and weathering.
• Explain and give examples of how physical evidence, such as fossils and surface features of glaciation, supports theories that the earth has evolved over geologic time.
Inquiry Skills:
• Observe the world from a scientific perspective.
• Articulate and explain the major concepts being investigated.
• Identify and use navigation features of a browser
• Using a browser, “bookmark” a Web site for future reference
• Using e-mail create and send a message
Resource: (visit link)
Additional Hints
(Decrypt)
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