Editing Oak Island (section)

===Geology===
The geology of Oak Island was first mapped in 1924 by J. W. Goldthwait of the [[Geological Survey of Canada]], who interpreted the island as a composite of four [[drumlin]]s.<ref name="Bathymetry Analysis">{{cite web|url=http://www.criticalenquiry.org/oakisland/fader_2.html|title=Bathymetry Analysis of the Oak Island area|author=Gordon B. J. Fader and Robert C. Courtney|work=www.criticalenquiry.org|access-date=February 6, 2019}}</ref> These drumlins are "elongated hills" which consist of multiple layers of [[till]] resting on bedrock and are from different phases of [[Glacial motion|glacial advance]] that span the past 75,000 years.<ref name="Archaeological Findings">{{cite web |url=https://www.oakislandtours.ca/uploads/5/0/8/8/50887171/a02_smiths_cove_oak_island_les_m_aug_2006.pdf |title=Review of Explorations, Archaeological Findings and Original Workings at Smith's Cove Oak Island, Nova Scotia|author=Les MacPhie and John Wonnacott|work=www.oakislandtours.ca|pages=7, 10, 12, 13, 17|date=August 12, 2006|access-date=February 6, 2019}}</ref> The layers on top of the [[bedrock]] are mainly made up of "Lawrencetown" and slate till. The former of these two is considered a type of [[clay]] till which is made up of 50% sand, 30% [[silt]], and 20% clay.<ref name="Archaeological Findings"/> In the main area that has been [[#Oak Island mystery|searched for treasure]] along with the till lie bits of [[anhydrite]] which become more [[Competence (geology)|competent]] deeper down. Researchers Les MacPhie, and John Wonnacott concluded that the deep deposits at the east end of the Island make up the drumlin formations.<ref name="Archaeological Findings"/>

There are two types of bedrock that lie under Oak Island; the southeastern portion consists of "[[Mississippian (geology)|Mississippian]] Windsor Group [[limestone]]" and [[gypsum]], and the northwestern part is [[Geologic time scale|Cambro-Ordovician]] Halifax Formation [[slate]].<ref name="Bathymetry Analysis"/> Oak Island and the area that is now [[Mahone Bay]] was once a [[lagoon]] 8,000 years [[Before Present|BP]], before the sea level rose with the melting glaciers.<ref name="Archaeological Findings"/> Dr. Ian Spooner of [[Acadia University]] has stated that the current triangular swamp on Oak Island was once a [[cove]]. Analysis done of core samples taken from the swamp show that a "significant [[Saline water|saltwater]] intrusion" occurred as recently as the late 1300s or early 1400s. While Spooner said that this was likely from "human manipulation", he did not rule out the possibility of an enormous storm.<ref>{{cite book|url=https://books.google.com/books?id=ZAvADQAAQBAJ&dq=Oak+Island+ian+spooner&pg=PT432|title=2020 Postscript: The Search Continues|work=The Curse of Oak Island: The Story of the World’s Longest Treasure Hunt|author=Randall Sullivan|publisher=Atlantic Monthly Press|year=2018|isbn=9780802189059}}</ref>