Potsdam Sandstone was highly regarded as a building material. There was extensive quarrying for Potsdam Sandstone in the Potsdam area, beginning in 1809. Properties of the rock that give it value as a building material include high compressive strength, attractive reddish coloring, and resistance to weathering. The rock also was said to be "soft and easy to carve" when freshly quarried but "extremely hard" and "weather-resistant" after exposure to the air, but modern geologists suggest that this is a misconception. Potsdam Sandstone resists spalling when exposed to fire, making it highly suitable for use as a refractory for lining iron furnaces. Local sandstone was used for many buildings in Potsdam, as well as for purposes such as gravestones and sidewalks. Buildings in other cities constructed with this rock include portions of Canada's Parliament Buildings (original Centre Block and Library of Parliament) in Ottawa, and the Cathedral of All Saints in Albany, New York. Potsdam Sandstone and its stratigraphic equivalents also have been quarried for use as building stone at several sites in Quebec. Stratigraphic equivalents and related units Stratigraphically equivalent and lithologically similar sandstone extends across the international border into Canada, although stratigraphic boundaries and nomenclature can differ. In Ontario, the Nepean Sandstone was formerly called "Potsdam" and is regarded as a stratigraphic equivalent to the Potsdam Sandstone. In Quebec, the Potsdam Group is recognized, consisting of the Covey Hill Formation and the Cairnside Formation, both of which are sandstones. Historically the name "Potsdam sandstone" was also applied to various other North American sandstone bodies that directly overlie Precambrian crystalline rocks, including sandstones in Canada, Pennsylvania, Virginia, Iowa, Wisconsin, Minnesota, Michigan, and Indiana, and attempts were made to identify or correlate various rocks with the Potsdam formation. The basal Cambrian sandstone formation in much of the upper Mississippi Valley and southern Great Lakes region is now designated the Mount Simon Sandstone and is, in turn, assigned to the Potsdam Supergroup, which takes its name from the Potsdam Sandstone. Similar quartz arenite sandstone found in Wyoming was also identified historically as the "Potsdam sandstone." See also List of sandstones References External links "The Potsdam Red Sandstone Quarries". Scientific American, Vol. LXVIII, No. 1, New York, January 7, 1893, pp. 1, 8–10. "The Potsdam Red Sandstone Company’s Water Wheel". Scientific American, Vol. LXVIII, No. 3, January 21, 1893, pp. 37–38. Building stone Cambrian geology of New York (state) Sandstone in Canada Cambrian