{{Short description|Geologic unit in eastern North America}} {{Infobox rockunit | name = Potsdam Sandstone | age = Latest {{Fossil range|Guzhangian|Furongian|refs=<ref>{{Cite FTP |author1=Salad Hersi, O. |author2=Lavoie, D. |name-list-style=amp |year=2000 |url=ftp://s5-bsc-faisan.cits.rncan.gc.ca/pub/geott/ess_pubs/211/211173/cr_2000_d04.pdf|server=FTP server |url-status=dead | title=Lithostratigraphic revision of the Upper Cambrian Cairnside Formation, upper Potsdam Group, southwestern Quebec. Geol. Surv. Canada, Curr. Res. D4, 1–8. }}</ref><ref>{{Cite book|url=https://books.google.com/books?id=qr0qAgAAQBAJ&q=Covey+Hill+formations&pg=PA503|title=The Great American Carbonate Bank: The Geology and Economic Resources of the Cambrian-Ordovician Sauk Megasequence of Laurentia, AAPG Memoir 98|isbn=9780891813804|last1=Derby|first1=James|last2=Fritz|first2=Richard|last3=Longacre|first3=Susan|last4=Morgan|first4=William|last5=Sternbach|first5=Charles|date=2013-01-20}}</ref>}} | period = Cambrian | image = SnellHall(2009).jpg | caption = Old Snell Hall at Clarkson University was built with Potsdam Sandstone.<ref name=ShortHistory>[http://www.potsdampublicmuseum.org/pages/97/20/sandstone-time-line-illustrated A Short History of Potsdam Sandstone], Potsdam Public Museum website, accessed July 29, 2011</ref> | type = Geological formation | prilithology = Orthoquartzite | otherlithology = Conglomerates, local siltstone lenses<ref>{{Cite journal | doi = 10.2475/ajs.261.2.108| title = The age of the Nepean (Potsdam) sandstone in eastern Ontario| journal = American Journal of Science| volume = 261| issue = 2| pages = 108–110| year = 1963| last1 = Kirwan | first1 = J. L.| bibcode = 1963AmJS..261..108K| doi-access = free}}</ref> | unitof = | subunits = *Cairnside Formation, Nepean Formation (Upper Cambrian) *Covey Hill Formation (?Middle Cambrian)<ref>{{Cite book|url=https://books.google.com/books?id=t6zw9qzPVtkC&q=Covey+Hill+formation&pg=PA6|title=Geological Survey of Canada, Open File 5900|last1=Lavoie|first1=D|last2=Hamblin|first2=A P|last3=Thúriault|first3=R|last4=Beaulieu|first4=J|last5=Kirkwood|first5=D}}</ref><ref>{{Cite web|url = http://weblex.nrcan.gc.ca/html/003000/GSCC00053003438.html|title = Covey Hill Formation}}</ref> *Mount Simon Sandstone<ref>{{Cite web|url = http://igs.indiana.edu/compendium/comp0i04.cfm|title = Compendium of Rocks Units in Indiana - A Revision}}</ref> | underlies = | overlies = | area = Eastern North America }} The '''Potsdam Sandstone''', more formally known as the Potsdam Group, is a geologic unit of mid-to-late Cambrian age found in Northern New York and northern Vermont and Quebec and Ontario. A well-cemented sandstone of nearly pure quartz, in the 19th century it was widely used in construction and in refractory linings for iron furnaces.<ref name=Carlqualities>James Carl, [http://potsdampublicmuseum.org/subpages/95/109/20/composition-and-qualities Potsdam Sandstone: Composition and Qualities], Potsdam Public Museum website, accessed July 29, 2011</ref>

==Name and type locality== [[File:PotsdamSandstone xbeds.jpg|thumb|right|Potsdam Sandstone outcrop along the Raquette River]] The Potsdam Sandstone is named for its type locality in Potsdam, New York, where in 1838 Ebenezer Emmons described it in outcrops along the Raquette River.<ref name=Geolex>[https://ngmdb.usgs.gov/Geolex/NewUnits/unit_3388.html Geologic Unit: Potsdam], U.S. Geological Survey Geolex Database, accessed August 1, 2011</ref><ref name=CarlBedrock>James Carl, [http://potsdampublicmuseum.org/subpages/95/110/20/bedrock-geology Potsdam Sandstone: Bedrock Geology], Potsdam Public Museum website, accessed July 29, 2011</ref>

==Stratigraphic setting and lithology== The Potsdam Sandstone lies unconformably on a surface of Precambrian metamorphic rock. It is the earliest unit in the marine-transgressive sedimentary rock sequence deposited during the early Paleozoic as sea level rose to gradually inundate the craton of the paleocontinent of Laurentia.<ref name=CarlBedrock/><ref name=Palaios/><ref name=Reynolds/> The rock, which is formed from sediments eroded off unvegetated terrestrial landscapes and deposited in near-shore coastal environments,<ref>{{Cite journal | doi = 10.2110/palo.2009.p09-134r| title = Dead in Their Tracks--Cambrian Arthropods and Their Traces from Intertidal Sandstones of Quebec and Wisconsin| journal = PALAIOS| volume = 25| issue = 8| pages = 475| year = 2010| last1 = Collette | first1 = J. H.| last2 = Hagadorn | first2 = J. W.| last3 = Lacelle | first3 = M. A.| bibcode = 2010Palai..25..475C| s2cid = 130051546}}</ref> consists almost entirely of sand-size quartz grains held together by quartz cement.<ref name=Carlqualities/><ref name=Palaios/> It ranges in color from gray to tan, yellow, and red, with the colors imparted by small amounts of the red iron oxide mineral hematite, Fe<sub>2</sub>O<sub>3</sub>, and the yellow iron oxide mineral goethite, FeO(OH).<ref name=Carlqualities/>

As sea level rose in the depositional environment, increasing amounts of carbonate minerals were deposited in the sediment, with the result that the unit grades upward into dolomitic sandstone in the upper Potsdam and then to sandy dolomite at the base of the overlying Theresa Formation.<ref name=Carlqualities/><ref name=Reynolds/><ref>[https://mrdata.usgs.gov/geology/state/sgmc-unit.php?unit=NYOCAth%3B1 Mineral Resources On-Line Spatial Data: Theresa Formation], U.S. Geological Survey Geolex, accessed August 6, 2011</ref>

==Geographic occurrence== [[File:Franklin noyau institutionnelle.JPG|thumb|right|Potsdam sandstone in 19th-century institutional architecture at Franklin, Quebec]] In New York state, the Potsdam is found primarily north and west of the Adirondack Mountains. Outcrop exposures of the Potsdam Sandstone occur throughout the Saint Lawrence lowlands, western Lake Champlain Valley, and northern Mohawk Valley. Ausable Chasm, near Plattsburgh, has a continuous exposure of a section more than {{convert|160|m|ft}} thick.<ref name=Palaios>James W. Hagadorn and Edward S. Belt (2008), Stranded in Upstate New York: Cambrian Scyphomedusae from the Potsdam Sandstone, ''PALAIOS'', v. 23, p. 424–441, {{doi|10.2110/palo.2006.p06-104r}} <!-- [http://www3.amherst.edu/~jwhagadorn/publications/04_HagadornBelt_new.pdf] --></ref> The formation reaches its maximum thickness of about {{convert|450|m|ft}} in the northern Champlain lowland.<ref name=Reynolds/>

Potsdam sandstone has been quarried commercially in Nepean, Ontario and Covey Hill, Quebec.<ref name="oc1">{{cite news |url=https://ottawacitizen.com/news/local-news/q-is-for-quarry-forgotten-overgrown-quarry-provided-the-building-blocks-of-ottawa}}</ref>

==Uses in construction and industry== [[File:Lieu historique national du Canada de la Mairie-de-Havelock 03.JPG|thumb|right|Havelock Town Hall, built from Potsdam sandstone quarried from Covey Hill, is a National Historic Site of Canada]] In the 19th century, Potsdam Sandstone was highly regarded as a building material. There was extensive quarrying for Potsdam Sandstone in the Potsdam area, beginning in 1809.<ref name=ShortHistory/><ref name=Carlqualities/><ref name=SciAm>[https://books.google.com/books?id=L4Y9AQAAIAAJ&pg=PA8 The Potsdam Red Sandstone quarries], ''Scientific American'', January 7, 1893, page 8-10.</ref><ref name=NYHeritagephoto/> Properties of the rock that give it value as a building material include high compressive strength, attractive reddish coloring, and resistance to weathering.<ref name=Carlqualities/><ref name=SciAm/><ref name=NYHeritagephoto/> 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.<ref name=Carlqualities/><ref name=NYHeritagephoto/>

Local sandstone was used for many buildings in Potsdam, as well as for purposes such as gravestones and sidewalks.<ref name=ShortHistory/><ref name=NYHeritagephoto/><ref>Lori Shull, [http://www.watertowndailytimes.com/article/20100920/NEWS05/309209994 Consultant tracking Potsdam sandstone, NNY stonemasons], ''Watertown (N.Y.) Daily Times'', September 20, 2010</ref>

Buildings in other cities constructed with this rock include portions of Canada's Parliament Buildings (original Centre Block and Library of Parliament) in Ottawa,<ref name=oc1/> and the Cathedral of All Saints in Albany, New York.<ref name=NYHeritagephoto>[http://history.nnyln.net/cdm4/item_viewer.php?CISOROOT=/ppm&CISOPTR=549&CISOBOX=1&REC=2 Potsdam Sandstone office] (photo and description), New York Heritage website, accessed July 29, 2011</ref> Potsdam Sandstone and its stratigraphic equivalents also have been quarried for use as building stone at several sites in Quebec.<ref name=mnq1>[http://www.mrnf.gouv.qc.ca/english/mines/industry/architectural/architectural-quarrying-history-sandstone-exploitation.jsp Architectural sandstone quarrying in Québec], Québec Ministry of Natural Resources and Wildlife website, accessed August 1, 2011</ref>

Potsdam Sandstone resists spalling when exposed to fire, making it highly suitable for use as a refractory for lining iron furnaces.<ref name=Carlqualities/><ref name=SciAm/>

==Stratigraphic equivalents and related units== [[File:Potsdam Sandstone Unconformity.tif|thumb|right|Unconformity at the base of the Potsdam Sandstone]] Stratigraphically equivalent and lithologically similar sandstone extends across the international border into Canada, although stratigraphic boundaries and nomenclature can differ.<ref name=Palaios>James W. Hagadorn and Edward S. Belt (2008), Stranded in Upstate New York: Cambrian Scyphomedusae from the Potsdam Sandstone, ''PALAIOS'', v. 23, p. 424–441, {{doi|10.2110/palo.2006.p06-104r}} <!-- [http://www3.amherst.edu/~jwhagadorn/publications/04_HagadornBelt_new.pdf] --></ref><ref name="Reynolds">John H. Williams, Richard J. Reynolds, David A. Franzi, Edwin A. Romanowicz, and Frederick L. Paillet (2010), [https://ny.water.usgs.gov/pubs/jrn/ip-003988/Williams_Reynolds_PotsdamSS_CWRJ.pdf Hydrogeology of the Potsdam Sandstone in Northern New York], ''Canadian Water Resources Journal'' Vol. 35(4): 399–416 (2010)</ref>

In Ontario, the Nepean Sandstone was formerly called "Potsdam" and is regarded as a stratigraphic equivalent to the Potsdam Sandstone.<ref>J. L. Kirwan (1963), [http://www.ajsonline.org/cgi/content/abstract/261/2/108 The age of the Nepean (Potsdam) sandstone in eastern Ontario], ''American Journal of Science'', Vol. 261, February 1963, P.108-110; {{doi|10.2475/ajs.261.2.108}}</ref><ref>[http://earth.uwaterloo.ca/outreach/rock-garden/potsdam-sandstone Potsdam sandstone] {{webarchive|url=https://web.archive.org/web/20110704142525/http://earth.uwaterloo.ca/outreach/rock-garden/potsdam-sandstone |date=2011-07-04 }}, University of Waterloo Earth and Environmental Sciences website, accessed July 29, 2011</ref><ref name=Bjerstedt/> In Quebec, the Potsdam Group is recognized, consisting of the Covey Hill Formation and the Cairnside Formation, both of which are sandstones.<ref name=Reynolds/>

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.<ref name=Bjerstedt>Thomas W. Bjerstedt and J. Mark Erickson (1989), Trace Fossils and Bioturbation in Peritidal Facies of the Potsdam-Theresa Formations (Cambrian-Ordovician), Northwest Adirondacks, ''Palaios'', Vol. 4, No. 3, June 1989, pp. 203-224</ref><ref name=IGS/><ref name=Walcott1891/> 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.<ref name=IGS>Indiana Geological Survey, [http://igs.indiana.edu/compendium/comp1hgk.cfm Potsdam Supergroup, St. Croixan Series, Cambrian System] and [http://igs.indiana.edu/compendium/comp0i04.cfm Mount Simon Sandstone, Potsdam Supergroup, Cambrian System], accessed July 29, 2011</ref> Similar quartz arenite sandstone found in Wyoming was also identified historically as the "Potsdam sandstone."<ref name=Walcott1891>Charles Doolittle Walcott (1891), [https://books.google.com/books?id=TSbwAAAAMAAJ&pg=PA211 Correlation Papers: Cambrian], ''Bulletin of the U.S. Geological Survey'', volume 15.</ref><ref>Francis John Pettijohn, Paul Edwin Potter, and Raymond Siever (1987), ''Sand and Sandstone'', Springer, {{ISBN|0-387-96350-2}}. Page 181.</ref>

==Paleontology== [[File:Potsdam Protichnites.jpg|thumb|right|''Protichnites'' in the lower Potsdam Sandstone.]] [[File:PotsdamSandstone Diplocraterion.jpg|thumb|right|''Diplocraterion'' in the upper Potsdam Sandstone.]] Fossil remains of whole animals are rare in the Potsdam Sandstone (although several relatively complete arthropods are known such as ''Aglaspis'' and ''Mictomerus''), but there are some significant occurrences of trace fossils. Trace fossils in the unit include both vertical burrows, such as ''Diplocraterion'' and ''Skolithos'' and horizontal trackways, such as ''Diplichnites'', ''Protichnites'', and ''Climactichnites''.<ref name=Palaios/><ref>James Carl, [http://potsdampublicmuseum.org/subpages/95/108/20/rock-structures-and-fossils Rock Structures and Fossils], Potsdam Public Museum website, accessed July 29, 2011</ref> In 1903, a 20-ton (18-tonne) slab of Potsdam Sandstone from Clinton County, New York, displaying tracks attributed to trilobites, was placed in the New York State Museum.<ref>[https://timesmachine.nytimes.com/timesmachine/1903/11/12/105066037.pdf The Trail of the Serpent], ''The New York Times'', November 12, 1903</ref> Fossil impressions of the whole bodies of jellyfish have also been found in the Potsdam.<ref name=Palaios/>

==See also== *List of sandstones

==References== {{reflist}}

==External links== *"[http://quarriesandbeyond.org/articles_and_books/pdf/potsdam_red_sandstone_quarries_scientific_american_january_7_1893.pdf The Potsdam Red Sandstone Quarries]". ''Scientific American'', Vol. LXVIII, No. 1, New York, January 7, 1893, pp.&nbsp;1, 8–10. *"[http://quarriesandbeyond.org/articles_and_books/pdf/potsdam_red_sandstone_cos_water_wheel_scientific_amer_jan_21_1893.pdf The Potsdam Red Sandstone Company’s Water Wheel]". ''Scientific American'', Vol. LXVIII, No. 3, January 21, 1893, pp.&nbsp;37–38.

Category:Building stone Category:Geology of New York (state) Category:Cambrian geology of New York (state) Category:Sandstone in Canada Category:Cambrian southern paleotemperate deposits Category:Sandstone in the United States Category:Geologic groups of New York (state) Category:Lagerstätten