One man's generosity played an integral role in the preservation of Chesterfield Gorge. George White, a local farmer, bought the land in 1936 to prevent encroaching loggers from clear-cutting it. He sold fifteen acres of the gorge to the Society for the Protection of New Hampshire Forests. The land was then donated to the State of New Hampshire.
The Visitor Center was created and is staffed due to volunteer support. The publications and exhibits in the center highlight the natural and cultural history of the region, as well as provide area information. A major display of early New Hampshire logging tools, donated by Mrs. H. T. Gregory of Norwich, Vermont, may be viewed.
The gorge is a naturally occurring geologic phenomenon located along Rt. 9 in Chesterfield, NH.
Geologists have three theories about the possible formation of Chesterfield Gorge. All the theories state that the rock bed of the gorge has been worn down by running water. Over thousands of years the stream has worn its path deeper and deeper into the bedrock. Ice has worked to break up the rock even more. As water in the cracks of the rock freezes, the ice expands to make large and small chunks break away from the cliffs. These two "weathering" forces continue to shape the gorge today.
But how did the stream get here in the first place? Here are the three theories:
One holds that the stream began in a fault. Faults are cracks in the Earth's crust in which rock on one side moves in relation to the other side. On either side of the crack the rock layers no longer line up.
The beds of the rock on the left moved downward in relation to the beds of rock on the right because of the fault. Upstream view. Rock Bed Plane Fault Line Gorge Brook
Do you see how one wall of the gorge is a vertical cliff and the other slopes about 30 degrees to the brook? The gorge may have been created as the sloped bank dropped down to make the cliff. You can simulate this action with your hands by putting the knuckles of your fists together, the top of your hands tilting to the right. Slip your your left hand down about half way and see the steep cliff of your right hand, with the trough for the stream and the 30 degree slope on the left. This kind of fault may have been the force that created Wilder Brook in the gorge.
The next theory holds that the gorge was created by erosion through a joint in the bedrock. A joint forms as a crack similar to a fault, but no movement occurs. However, as the joint forms, the adjacent rock develops small cracks and becomes much weaker than the surrounding solid rock. In this weakened area, weathering can occur and erosion can take place more quickly. Thus the stream would have entered this crack about 10,000 years ago and started cutting the gorge. If this theory is true, nearly 60 feet of rock has been worn down by water and ice in the 12,000 years since glacial times!
|The brook cuts down the joint and along the plane of the bed. Upstream view.|
The third theory says that the stream in Chesterfield Gorge is a superimposed stream, as are many in the Monadnock Region. The stream may have started as a glacial meltwater stream, flowing over sands and gravels that covered this area in late glacial times. For the first several thousand years, the stream would have been busy stripping away the sands and gravels until reaching the bedrock, and then cutting the gorge for several thousand more and continuing into the present. So the stream was "superimposed" upon the bedrock. This is a very tough metamorphic rock and greatly slowed the stream's down cutting. The structure and toughness of the bedrock have controlled the stream and the development of Chesterfield Gorge. As the bedrock in the area of the gorge finally came to rest as it is today the layers of the bedrock were not parallel to the Earth's surface but rather sloped downward at about a 4- degree angle to the south. As the stream proceeded to cut down deeper into the bedrock, this south-dipping attitude of the bedrock caused the stream to erode and undercut the south side of its channel in the bedrock. This could explain why the south wall of the gorge is vertical, while the north wall is steep, but much more gentle that the south.
The slope of the north wall approximates the dip of the bedrock. This is best seen from a viewpoint near the base of the gorge and on the trail along the south rim.
|The stream flow cuts through bedrock and is thrown to the south side by the inclined layers.|
||Developmental Stages of Brook|
|Rock Bed Plane|
Though the stream has been flowing for thousands of years, it is still classified as a "youthful stream", having a steep gradient, steep walls, little rapids and falls, and a very irregular, angular course. The many right-angled turns in the stream are again due to rock structure as the water flows along joint fractures and down over eroded edges of rock layers.
One can also note evidence of other natural processes contributing to the development of the gorge: roots and frost wedging into the boulders causing them to split, the creep of soil and rocks downstream, and debris in the stream bed, which tend to move in the more energetic waters of spring.
Which theory sounds best to you? Can you tell if the rock layers on the cliff side line up with those on the other side? Does some rock look or feel weaker than the rest? Whichever theory or combination of ideas you believe, Wilder Brook is still wearing away the rock bed and the gorge continues to get deeper day by day.
The stream through the gorge originates in two swampy ponds uphill from the park. The fast-moving water thrashes its way through the gorge and then settles down into the more sedate waters of Partridge Brook. Ten miles downstream this flow merges with the Connecticut River, which continues its winding course out to sea.
Now look closely at the stream. Everyone knows that streams flow downhill, right? This is not always true. The general trend is downhill, but if you search closely, you can find small pockets of water defying gravity and flowing uphill. The eddies are often found behind rocks and other obstructions in the stream. An eddy is like the calm eye of a hurricane. In large rivers, canoers and kayakers take advantage of eddies to perch their boats in the midst of raging torrents. Find yourself a tiny boat (a small stick, 2-3 inches long) and toss it into an eddy where you will see it stay put and not flow downstream. Chalklenge yourself to find eddies in the fast-flowing cascades of the gorge.
You may see clumps of soap-sudsy brownish fluff floating on the stream. This is not pollution from somebody's washing machine, but is actually evidence of minerals in the water from decomposing wood and roots. It is a natural product of the stream and is not harmful. Rub some between your fingers, it looks soapy, but is not slippery.
Coimmunity is a familiar word to most people. We all live in a community of one kind or another. At the beginning of the gorge trail you stand in a community of plants dominated by sun-lovong oak and pine trees. As you walk the trail, you will descend into a different plant community called a hemlock gorge named for the stately evergreens that prevail there.
Different kinds of plants need various amounts of sunlight, moisture, and heat in order to grow. Take note of changes in these cactors as you walk down the trail.
Along the brook, you'll notice evergreen trees with deeply furrowed bark and short, slender needles that have two white lines on the underside. These are the hemlocks. Hemlocks thrive on abundant moisture and coolness and manage to grow on the thinnest of soils. In many places you'll see hemlocks that have wrapped their roots around rocks or draped them over ledges.
Hemlocks set the tone for the plant community that lives in Chesterfield Gorge. Their root systems take up much of the available nutrient material in the soil, leaving little for other plants to grow. Their boughs shade out much sunlight, inhibiting the growth of all but the most shade-tolerant plants. The high, rock walls of the gorge also shut out direct sunlight and hold in evaporation from the stream, maintaining a cool, damp microclimate.
Three other trees do grow well in these conditions and can be found in the gorge. Beech has a smooth, light gray bark and a muscular-looking trunk. The yellow birch is distinguished by its shiny yellowish bark that peels off in tatters and fringes. The black birch has smooth, dark gray to black bark and emits a pungent, sweet odor when its twigs are broken.
On the forest floor you may see the three dark green leaves of the wintergreen plant. The leaves of this small creeping vine have a pleasant minty smwll when crushed. Other moisture-lovong, shade tolerant plants such as mosses and ferns are plentiful (common polypody shown at left).
On the rocks grow the hardiest of all plants, the lichens. They are a mixture of fungus and alga. The fungus feeds on the alga and the alga recieves protection from wind and loss of water. This allows them to grow together where neither could on its own. Lichen can tolerate low levels of light and no direct light; neither do they require soil. The growth of lichen tends to break down the surface of the rock. As lichens grow and die, soil-building material is accumulated. These factors make it possible for other plants, such as mosses, to grow. Scientists call them pioneers, and rightly so.
Please enjoy your hike in the gorge and carry out all liter so that others may enjoy it too.
Other Monadnock Region Parks
Annett Wayside Park
Mount Monadnock State Park
Greenfield State Park
Miller State Park
Pisgah State Park
Rhododendron State Park