Ausable Chasm

'' trace fossils found at Ausable Chasm. Ausable Chasm is carved out of a 500-million-year-old, -thick exposure of Cambrian Potsdam Sandstone. The sandstone of the gorge, formed from ancient tidal flats, preserves ripple marks, ichnofossils, 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. The formation of Ausable Chasm began in its earnest when post-glacial rebound caused the Champlain Sea to recede, and the Ausable River, with considerably higher flow than today due to glacial meltwater, Modern development of the gorge has effectively been halted due to the construction of a dam upstream and the diversion of water from Rainbow Falls. ==History==

Archeological evidence for Native American settlement has been found close to Ausable Chasm at Hallock Hill. In the 17th century, the land surrounding Ausable Chasm was contested between Mohawk people of the Iroquois Confederacy and Algonquian tribes. Native Americans left the area around 1810. In 1760, Major John Howe explored the chasm on ropes. Five years later in 1765, early Irish settler William Gilliland encountered the chasm while exploring the shore of Lake Champlain on a bateau. Gilliland wrote in his journal that the gorge "is a most admirable sight, appearing on each side like a regular built wall, somewhat ruinated, and one would think that this prodigious clift was occasioned by an earthquake, their height on each side is from 40 to 100 feet in the different places; we saw about a half a mile of it, and by its appearance where we stopped it may continue very many miles further." Although Gilliland's settlement was destroyed during the American Revolutionary War, In 1925, the AuSable Chasm Bridge was inaugurated, spanning the chasm at its southern extreme carrying US 9 over the Ausable River. ==Tourism==

and Rainbow Falls Formal tourism at the chasm began in 1873 with the formation of the Ausable Company by a group of Philadelphia businessmen. Tours of the chasm were offered by bateau for 25¢, and wooden walkways were constructed. In 1897, sitting president William McKinley visited the chasm and rode the rapids on the Ausable River. Later, silent movies including Three Jumps Ahead filmed at the chasm, sometimes using it as a dramatic backdrop for stunts. In January and November 1996, the chasm was hit by two devastating floods. The first, on January 19th, was caused by the rapid snowmelt in the Adirondack Mountains due to unseasonably warm temperatures. Although the tourist infrastructure around the chasm was devastated, it was rebuilt and substantially strengthened. Nevertheless, on November 9th, seven inches of rainfall resulted in a 100-year flood, which ripped apart the newly strengthened infrastructure. After the second flood, most of the tourist trails in the chasm were rerouted to higher ground. The chasm, advertised as the "Grand Canyon of the Adirondacks", is presently operated as a tourist attraction which can be toured after a fee. In addition to five miles of trails which extend around and inside the chasm, activities offered include rock climbing, whitewater rafting and a via ferrata. ==Cultural attractions==

• North Star Underground Railroad Museum, commemorating the Underground Railroad and operated by the North Country Underground Railroad Historical Association, is on Mace Chasm Road in Ausable Chasm, New York on County Route 71, south of the junction of County Route 373 and U.S. 9. ==Gallery==

Image:AusableChasmPointLookout.JPG | Lookout Point Image:RainbowFallsAusableChasm.JPG | Rainbow Falls Image:HotelAusableChasm.JPG | Hotel Ausable Chasm ==References==