The Flume Gorge (locally, just The Flume) is a natural

gorge A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosion, erosive activity of a river over geologic time scales. Rivers have a natural tend ...

extending horizontally at the base of Mount Liberty in Franconia Notch State Park,

New Hampshire New Hampshire ( ) is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. Cut by Flume Brook, the gorge features walls of Conway granite that rise to a height of and are apart. Discovered in 1808 by 93-year-old "Aunt" Jess Guernsey, the Flume is now a paid attraction that allows visitors to walk through it from May 10 to October 20. Pets are not allowed.

Geology

Nearly 200 million years ago in the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

period, the Conway granite that forms the walls of the Flume was deeply buried molten rock. As it cooled, the granite was broken by closely spaced vertical fractures that lay nearly parallel in a northeasterly direction. Sometime after the fractures were formed, small dikes of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

were forced up along the fractures. The basalt came from deep within the earth as a fluid material, and because of pressure, was able to force the Conway granite aside. The basalt crystallized quickly against the relatively cold granite. Because of this quick cooling, the basalt is a fine-grained rock. Had this material ever reached the surface, it would have become

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

flows.

Erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

gradually lowered the earth's surface and exposed the dikes. As the overlying rock was worn away, pressure was relieved and horizontal cracks developed, allowing water to get into the rock layers. The basalt dikes eroded faster than the surrounding Conway granite, creating a deepening valley where the gorge is now. The gorge was covered by glaciers during the

Ice Age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...

, but the ice sheet did not greatly change the surface. It partially filled the valley with glacial debris and removed soil and weathered rock from the vicinity. After the Ice Age, Flume Brook began to flow through the valley again. The highly fractured granite and basalt have been eroded by frost action and by the brook's water. As one walks through the Flume Gorge, at the floor one may notice remnants of the main basalt dike, and that small trees are growing on the walls of the gorge. Erosion is still occurring.

Discovery

The Flume was discovered in 1808 by 93-year-old "Aunt" Jess Guernsey when she accidentally came upon it while fishing. She had trouble convincing her family of the marvelous discovery, but eventually persuaded others to come and see for themselves. At that time, a huge, egg-shaped boulder hung suspended between the walls. The rock was high and long. A heavy rainstorm in June 1883 started a landslide that swept the boulder from its place. The boulder has never been found. The same storm deepened the gorge and formed Avalanche Falls.

References

External links

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Flume Gorge and Visitor Center
NH Division of Parks & Recreation 1808 in science Canyons and gorges of New Hampshire Landmarks in New Hampshire Parks in Grafton County, New Hampshire Waterfalls of New Hampshire Landforms of Grafton County, New Hampshire Lincoln, New Hampshire

Geology

Discovery

See also

References

External links