Ausable Chasm
sandstone gorge near Keeseville, NY, USA
Ausable Chasm is a sandstone gorge and tourist attraction located near the hamlet of Keeseville, New York, United States, due west of Port Kent. The gorge is about two miles (3.2 km) long and is about 150 feet (46 m) deep.
Ausable Chasm is the namesake of the Ausable River, which runs through the gorge and empties into Lake Champlain about one mile (1.6 km) away. The gorge started forming about 10,000 years ago through headward erosion caused by Rainbow Falls, a 91 feet (28 m) waterfall at the gorge's southern extreme. The gorge is a major tourist attraction and landmark in the Adirondacks region of Upstate New York.
Geology
Ausable Chasm is carved out of a 500-million-year-old, 520-foot (160 m)-thick exposure of Cambrian Potsdam Sandstone. The sandstone of the gorge, formed from ancient tidal flats, preserves ripple marks, ichnofossils, and rare mid-Cambrian Scyphomedusae jellyfish fossils.
Ausable Chasm itself is a result of the conclusion of the last glacial period at the end of the Pleistocene, about 10,000 years ago. Prior to the formation of the gorge, the movement of the Laurentide ice sheet during the last glacial period carved deep cliffs along the Champlain Valley, which were subsequently covered in glacial till. By the end of the last glacial period, the melting ice sheets formed the vast Champlain Sea, which inundated the current location of the chasm.
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This entry incorporates text from “Ausable Chasm” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.