Editing Cape Cod (section)

==Geology==
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| quote    = '''''"East of America, there stands in the open Atlantic the last fragment of an ancient and vanished land. Worn by the breakers and the rains, and disintegrated by the wind, it still stands bold."'''''
| source   = {{small|[[Henry Beston]], ''[[The Outermost House]]''}}
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[[File:Cape Cod Landsat 7.jpg|thumb|left|Cape Cod was formed by retreating glaciers<ref>{{cite web|url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17067 |title=Provincetown Spit, Cape Cod, Massachusetts |publisher=[[NASA Earth Observatory]] |access-date=May 2, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060930230755/http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17067 |archive-date=September 30, 2006 }}</ref>]]
[[File:Geologic Map of Cape Cod.jpg|thumb|Geologic makeup of Cape Cod]]

The bulk of the land on Cape Cod consists of [[glacial landform]]s, formed by [[terminal moraine]] and [[outwash plain]]s. This represents the southernmost extent of glacial coverage in southeast New England; similar glacial formations make up [[Long Island]] in New York and [[Block Island]] in [[Rhode Island]]. Together, these formations are known as the [[Outer Lands]], or more obscurely as the "Isles of Stirling". Geologically speaking, Cape Cod is quite young, having been laid down some 16,000 to 20,000 years ago.

Most of Cape Cod's geological history involves the advance and retreat of the [[Laurentide Ice Sheet]] in the late [[Pleistocene]] geological era and the subsequent changes in sea level.<ref name="conway">{{cite book |last1=Conway |first1=J. North |title=The Cape Cod Canal: Breaking Through the Bared and Bended Arm |date=2008 |publisher=Arcadia Publishing Incorporated |isbn=9781625843821}}</ref>{{rp|28}} Using [[radiocarbon dating]] techniques, researchers have determined that around 23,000 years ago, the ice sheet reached its maximum southward advance over North America, and then started to retreat. Many [[Kettle (landform)|kettle ponds]] – clear, cold lakes – were formed and remain on Cape Cod as a result of the receding glacier. By about 18,000 years ago, the ice sheet had retreated past Cape Cod. By roughly 15,000 years ago, it had retreated past southern New England. With so much of Earth's water locked up in massive ice sheets, the sea level was lower. Truro's bayside beaches used to be a petrified forest before it became a beach.

[[File:Deposition erosion.jpg|thumb|[[Coastal erosion]] by wave action (colored buff in this map) brings growth elsewhere by [[Deposition (geology)|deposition]] of transported sediment (shown in blue).]]
As the ice began to melt, the sea began to rise. Initially, sea level rose quickly, about {{convert|15|m|ft}} per 1,000 years, but then the rate declined. On Cape Cod, sea level rose roughly {{convert|3|m|ft}} per millennium between 6,000 and 2,000 years ago. After that, it continued to rise at about {{convert|1|m|ft}} per millennium. By 6,000 years ago, the sea level was high enough to start eroding the glacial deposits that the vanished continental ice sheet had left on Cape Cod. The water transported the eroded deposits north and south along the outer Cape's shoreline through a process known as [[longshore drift]]. Those reworked sediments that moved north went to the tip of Cape Cod. The entire town of Provincetown, at the extreme tip of the Cape, is a [[Spit (landform)|spit]] consisting largely of deposited [[marine sediment]] that was eroded and transported from farther south along the shore. Those sediments that instead moved south created the islands and shoals of Monomoy. So while other parts of the Cape have dwindled from the action of the waves, these parts of the Cape have grown through the [[Deposition (geology)|deposition]] of sediment in just the last 6,000 years.

This process continues today. Due to their exposure to the open ocean, the Cape and islands are subject to considerable [[coastal erosion]]. Due to erosion, the Cape will be completely submerged by the sea within several thousand years.<ref>{{cite web| url=https://woodshole.er.usgs.gov/staffpages/boldale/capecod/quest.html| title=Coastal Erosion on Cape Cod: Some Questions and Answers| author=Oldale, Robert N| access-date=November 30, 2007| publisher=WoodsHole.er.usgs.gov}}</ref> This erosion causes the washout of beaches and the destruction of the barrier islands; for example, the ocean broke through the barrier island at Chatham during [[Hurricane Bob]] in 1991, allowing waves and storm surge to hit the coast with no obstruction. Consequently, the sediment and sand from the beaches are being washed away and deposited elsewhere. While this destroys land in some places, it creates land elsewhere, most noticeably in marshes where sediment is deposited by flowing water.

Cape Cod's aquifer consists of six hydrologically independent [[Lens (hydrology)|lenses]] from which all the towns on the Cape obtain drinking water (except Falmouth, which, in 2015, drew 43.5% of its water from Long Pond).<ref>[http://www.mass.gov/eea/docs/eea/water/assess-rpt-capecod.pdf "Cape Cod Watershed Assessment"], www.mass.gov</ref><ref>{{cite web |url=http://www.falmouthmass.us/depart.php?depkey=water |title=Town of Falmouth - Water Department |access-date=August 4, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160720213407/http://www.falmouthmass.us/depart.php?depkey=water |archive-date=July 20, 2016 }}</ref> Contamination with industrial chemicals and pharmaceutical drugs from septic systems is a concern.<ref>{{cite web|url=http://www.silentspring.org/research-area/water-research|title=Water Research|date=July 30, 2013}}</ref> In 2023, the state began a nitrogen pollution regulation scheme for Cape Cod and the Islands to address overgrowth of algae, cyanobacteria, and plants.<ref>{{cite web |url=https://www.bostonglobe.com/2023/06/21/science/healey-administration-unveils-new-permit-system-address-cape-water-pollution/ |title=Healey administration unveils new permit system to address Cape water pollution
|author1=Michael P. Norton |author2=Sam Drysdale |website=[[The Boston Globe]]
|agency=State House News |date=June 21, 2023}}</ref>

[[File:Cape Cod ISS.JPG|thumb|View of Cape Cod from the [[International Space Station|ISS]]]]