Central Park

===Geology===
[[File:Rat rock east face Feb jeh.jpg|thumb|upright=1|alt=East side of Rat Rock with high rise buildings in the background|East side of [[Rat Rock (Central Park)|Rat Rock]]]]
There are four different types of [[bedrock]] in Manhattan. In Central Park, [[Manhattan schist]] and Hartland schist, which are both metamorphosed [[sedimentary rock]], are exposed in various [[outcrop]]pings. The other two types, [[Fordham gneiss]] (an older deeper layer) and [[Inwood marble]] (metamorphosed [[limestone]] which overlays the [[gneiss]]), do not surface in the park.{{sfn|Kinkead|1990|pp=220–221}}{{sfn|McCully|2006|p=6}}{{sfn|Merguerian|Merguerian|2004|p=1}} Fordham gneiss, which consists of metamorphosed [[igneous rock]]s, was formed a billion years ago, during the [[Grenville orogeny]] that occurred during the creation of an ancient super-continent. Manhattan schist and Hartland schist were formed in the [[Iapetus Ocean]] during the [[Taconic orogeny]] in the [[Paleozoic]] era, about 450&nbsp;million years ago, when the tectonic plates began to merge to form the supercontinent [[Pangaea]].<ref>{{Cite web|url=https://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70544.htm |title=Deformational History Of The Manhattan Rocks And Its Relationship With The State Of In-Situ Stress In The New York City Area, New York|date=March 25, 2004|last1=Shah|first1=A.N.|last2=Chang|first2=C.C. |last3=Kim|first3=K.|publisher=Geological Society of America|volume=36|issue=2|access-date=April 15, 2019|archive-url= https://web.archive.org/web/20181118121521/https://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70544.htm |archive-date=November 18, 2018}}</ref> [[Cameron's Line]], a [[fault zone]] that traverses Central Park on an east–west axis, divides the outcroppings of Hartland schist to the south and Manhattan schist to the north.{{sfn|Merguerian|Merguerian|2004|pp=7–8}}

Various glaciers have covered the area of Central Park in the past, with the most recent being the [[Wisconsinan glaciation|Wisconsin glacier]] which receded about 12,000&nbsp;years ago. Evidence of past glaciers can be seen throughout the park in the form of [[glacial erratic]]s (large boulders dropped by the receding glacier) and north–south glacial striations visible on stone outcroppings.{{sfn|Kinkead|1990|pp=220–221}}<ref name="Broad 2018">{{Cite news|url=https://www.nytimes.com/2018/06/05/science/how-the-ice-age-shaped-new-york.html |title=How the Ice Age Shaped New York|last=Broad|first=William J|date=June 5, 2018|work=The New York Times|access-date=April 15, 2019 |issn=0362-4331|archive-url=https://web.archive.org/web/20190508055054/https://www.nytimes.com/2018/06/05/science/how-the-ice-age-shaped-new-york.html|archive-date=May 8, 2019|url-status=live}}</ref><ref>{{Cite web |url=https://www.nycgovparks.org/about/history/geology|title=Geological History of NYC Parks|publisher=New York City Department of Parks and Recreation|access-date=April 15, 2019|archive-url=https://web.archive.org/web/20190504193725/https://www.nycgovparks.org/about/history/geology|archive-date=May 4, 2019|url-status=live}}</ref> Alignments of glacial erratics, called "boulder trains", are present throughout Central Park.<ref>{{Cite news|url=https://www.nytimes.com/2005/09/14/nyregion/the-very-cold-case-of-the-glacier.html |title=The Very Cold Case of the Glacier|last=Collins|first=Glenn|date=September 14, 2005|work=The New York Times |access-date=April 15, 2019|issn=0362-4331|archive-url=https://web.archive.org/web/20171214012226/http://www.nytimes.com/2005/09/14/nyregion/the-very-cold-case-of-the-glacier.html|archive-date=December 14, 2017|url-status=live}}</ref> The most notable of these outcroppings is [[Rat Rock (Central Park)|Rat Rock]] (also known as Umpire Rock), a circular outcropping at the southwestern corner of the park.<ref name="Broad 2018"/>{{sfn|Sherman|1994|pp=226–228}} It measures {{convert|55|ft|m}} wide and {{convert|15|ft|m}} tall with different east, west, and north faces.{{sfn|Sherman|1994|pp=226–228}}<ref name="Bleyer 2007">{{cite web |url=https://www.nytimes.com/2007/10/07/nyregion/thecity/07boul.html |title=The Zen of the Rock|last=Bleyer|first=Jennifer|date=October 7, 2007|work=The New York Times|issn=0362-4331|access-date=April 19, 2019|archive-url=https://web.archive.org/web/20190419153254/https://www.nytimes.com/2007/10/07/nyregion/thecity/07boul.html|archive-date=April 19, 2019|url-status=live}}</ref> [[Bouldering|Boulderers]] sometimes congregate there.<ref name="Bleyer 2007"/>  A single [[Kettle (landform)|glacial pothole]] with yellow clay is near the southwest corner of the park.{{sfn|Merguerian|Merguerian|2004|p=18}}{{sfn|Kinkead|1990|p=224}}

The underground geology of Central Park was altered by the construction of several subway lines underneath it, and by the [[New York City Water Tunnel No.&nbsp;3]] approximately {{Convert|700|ft|m|abbr=}} underground. Excavations for the project have uncovered [[pegmatite]], [[feldspar]], [[quartz]], [[biotite]], and several [[metal]]s.{{sfn|Kinkead|1990|pp=225–226}}