Editing Key Biscayne (section)

==Geography==
Key Biscayne, although named a "key", is not [[Geology|geologically]] part of the [[Florida Keys]],<ref>{{cite web|title=The Emerald Keys|url=http://www.nps.gov/archive/bisc/resource/island.htm|publisher=National Park Service|access-date=13 December 2014|archive-url=https://web.archive.org/web/20080601015911/http://www.nps.gov/archive/bisc/resource/island.htm|archive-date=1 June 2008}}</ref> but is a [[barrier island]] composed of sand [[Erosion#Water|eroded]] from the [[Appalachian Mountains]], carried to the coast by rivers and then [[Longshore drift|moved]] along the coast from the north by coastal currents.{{sfn|Lodge|2010|p=174}} The eastern edge of Key Biscayne is underlain by the [[Key Largo Limestone]], a fossilized ancient reef that is exposed in the upper and middle Florida Keys.{{sfn|Leynes|Cullison|1998|pp=7–8}} Elsewhere, there is no hard bedrock near the surface of the island, only layers of weak [[sandstone]] to depths of {{convert|100|ft|m}} or more.{{sfn|Blank|1996|p=150}} The coastal transport of sand southward ends at Key Biscayne. In the 1850s, [[Louis Agassiz]] noted that "[s]outh of [[Cape Florida]] no more [[quartz|silicacious]] sand is to be seen."{{sfn|Blank|1996|p=75}} (The beaches in the Florida Keys, by contrast, consist primarily of finely pulverized shells.){{sfn|Blank|1996|p=36}} [[Geologist]]s believe that the island emerged around 2000 [[Common Era|BCE]], soon after the [[Sea level#Change|sea level]] stopped rising, as the sand built up to form new barrier islands on the southern Florida coast.{{sfn|Blank|1996|p=3}}

Key Biscayne is elongated in the north–south direction, tapering to a point at each end. It is approximately {{convert|5|mi|km}} long and {{convert|1|to|2|mi|km}} wide. The northern end of the island is separated from another barrier island, [[Virginia Key]], by Bear Cut. The southern end of the island is Cape Florida. The Cape Florida Channel separates the island from the [[Safety Valve (Biscayne Bay)|Safety Valve]], an expanse of shallow flats cut by tidal channels that extends southward about {{convert|9|mi|km}} to the [[Ragged Keys]], at the northern end of the Florida Keys.

Only [[Soldier Key]], approximately {{convert|200|by|100|yd|m}} wide, lies between Key Biscayne and the Ragged Keys.{{sfn|Voss|Voss|1955|p=204}} The Cape Florida Channel, {{convert|10 to 11|ft}} deep in 1849, and Bear Cut, {{convert|4|ft}} deep in 1849, are the deepest natural [[Channel (geography)|channels]] into Biscayne Bay. They provided the only access for ocean-going vessels to Biscayne Bay until artificial channels were dredged starting early in the 20th century. In 1849 the island had a fine sandy beach on the east side, and [[mangrove]]s and [[lagoon]]s on the west side.{{sfn|Blank|1996|pp=26, 63–68}} The average elevation of the island is less than {{convert|5|ft|m|spell=in}} above [[sea level]].{{sfn|Blank|1996|p=172}}

Key Biscayne is located at {{coord|25|41|25|N|80|9|54|W|type:city}} (25.690329, -80.165118).<ref name="GR1">{{cite web|url=https://www.census.gov/geo/www/gazetteer/gazette.html|publisher=[[United States Census Bureau]]|access-date=2011-04-23|date=2011-02-12|title=US Gazetteer files: 2010, 2000, and 1990|archive-url=https://web.archive.org/web/20020527061848/http://www.census.gov/geo/www/gazetteer/gazette.html|archive-date=2002-05-27|url-status=dead}}</ref>