View source for Earth:Middlesboro crater

{{Infobox terrestrial impact site
| name = Middlesboro crater
| other_name = Middlesborough astrobleme
| photo = Middlesboro, Kentucky; viewed from the Pinnacle Overlook in April, 2013..jpg
| photo_size =
| photo_alt =
| photo_caption = The city of Middlesboro is built within the crater
| location = Bell County, Kentucky, {{wipe|United States}}
| map = Kentucky
| map_alt =
| map_caption = Location of Middlesboro Crater in Kentucky
| map_size =
| label_position =
| coordinates = {{coord|36|37|N|83|44|W|region:US-KY|format=dms|display=inline,title}}
| coordinates_ref =
| confidence = Confirmed<ref name="EID">{{Cite Earth Impact DB | name = Barringer | accessdate = 2013-08-26 }}</ref>
| diameter = {{convert|6|km|mi|sp=us}}
| age = <300 Ma<br>[[Earth:Permian|Permian]] to late [[Earth:Mesozoic|Mesozoic]]
| exposed = Yes
| drilled = Yes
| bolide = 
| topo =
| access = U.S. Route 25E
| country = {{wipe|United States}}
| state = Kentucky
| province =
| district =
| municipality =
}}

The '''Middlesboro crater''' (or '''astrobleme''') is a [[Astronomy:Meteorite|meteorite]] [[Astronomy:Impact crater|crater]] in Kentucky, United States.<ref>{{Cite Earth Impact DB | name = Middlesboro | accessdate = 2008-12-30 }}</ref> It is named after the city of Middlesborough (both spellings are used), which today occupies much of the crater.

The crater is approximately 3 miles (about 5&nbsp;km) wide and its age is estimated to be less than 300 million years ([[Earth:Permian|Permian]]). The impactor is estimated to have been about 100 m in diameter. 

==History==
The Middlesboro crater is located in the Appalachian Mountains, between the Cumberland Mountains and Pine Mountain.  It forms part of the string of geological features that made the Cumberland Gap a critical westward passage during the settlement of Kentucky and the Ohio Valley in the late 18th and early 19th centuries.

== Settlements ==
The town of Middlesboro, built in the crater, was established in 1886 to exploit [[Chemistry:Iron|iron]] and [[Earth:Coal|coal]] deposits,<ref>[http://www.diolex.net/stmarys/Community.htm] {{webarchive |url=https://web.archive.org/web/20060511000016/http://www.diolex.net/stmarys/Community.htm |date=May 11, 2006 }}</ref> although the town's founder, Alexander A. Arthur, apparently did not know of the crater's extraterrestrial origin.  K. J. Englund and J. B. Roen, working for the U. S. Geological Survey, identified the impact basin in 1962.<ref>{{cite web|author=K. A. Milam, J. Evenick, and B. Deane eds. |title=Field Guide to the Middlesboro and Flynn Creek Impact Structures |url=http://web.eps.utk.edu/~faculty/tennmaps/lectures/MiddlesboroGuide.pdf |accessdate=November 13, 2012 |publisher=Impact Field Studies Group |url-status=dead |archiveurl=https://web.archive.org/web/20140106031520/http://web.eps.utk.edu/~faculty/tennmaps/lectures/MiddlesboroGuide.pdf |archivedate=January 6, 2014 }}</ref>

==Geological features==
The {{convert|12|mi|km|sing=on}} long Cumberland Gap consists of four geologic features: the Yellow Creek valley, the natural gap in the Cumberland Mountain ridge, the eroded gap in Pine Mountain, and Middlesboro crater.

Middlesboro crater is a {{convert|3|mi|km|sing=on}} diameter [[Astronomy:Meteorite|meteorite]] [[Astronomy:Impact crater|impact crater]] in which Middlesboro, Kentucky, is located. The crater was identified in 1966 when [[Biography:Robert S. Dietz|Robert Dietz]] discovered [[Astronomy:Shatter cone|shatter cone]]s in [[Earth:Sandstone|sandstone]], which led to the further identification of [[Chemistry:Shocked quartz|shocked quartz]]. Shatter cones, a rock shattering pattern naturally formed only during [[Astronomy:Impact event|impact event]]s, are found in abundance in the area. In September 2003 the site was designated a Distinguished Geologic Site by the Kentucky Society of Professional Geologists.<ref>{{cite journal | author=Kortenkamp, Steve |date=Summer 2004 | title=Impact at Cumberland Gap: Where Natural and National History Collide | journal=PSI Newsletter | volume=5 | issue=2 | pages=1–2 | url=http://www.psi.edu/newsletter/summer04/Summer04
 }}</ref>

Without Middlesboro crater, it would have been difficult for packhorses to navigate this gap, formed by differential erosion along one of the subsequent cross faults, {{Citation needed|date=May 2010}} and improbable that wagon roads would have been constructed at an early date. Middlesboro is the only place in the world where [[Earth:Coal|coal]] is mined inside an impact crater. Special mining techniques must be used in the complicated strata of this crater. (Milam & Kuehn, 36).

[[Image:Cumberland Gap Pinnacle Overlook.jpg|640px|thumb|center|Panoramic view from Pinnacle Overlook at Cumberland Gap National Historic Park]]

== Industrial activity ==
While coal mining is still the town's primary economic driver, local leaders hope to turn the crater into a tourist destination.<ref>{{cite web|agency=Associated Press|title=Kentucky town sees a future in its crater|publisher=St. Petersburg Times |date=2003-09-20|accessdate=September 16, 2006 |url=http://www.sptimes.com/2003/09/20/Worldandnation/Kentucky_town_sees_a_.shtml}}</ref> In 2003, the Kentucky Society of Professional Geologists designated the area a Distinguished Geologic Site,<ref>{{cite journal | author=Kortenkamp, Steve |date=Summer 2004 | title=Impact at Cumberland Gap: Where Natural and National History Collide | journal=PSI Newsletter | volume=5 | issue=2 | pages=1–2 | url=http://www.psi.edu/sites/default/files/imported/news/newsletter/summer04/Summer04.pdf }}</ref> and the construction of the Cumberland Gap Tunnel makes the town a convenient source of supplies for visitors to Cumberland Gap National Historical Park.

== References ==
{{reflist}}

==External links==
*[http://craterexplorer.ca/middlesboro-impact-crater// Exploration of the Middlesboro impact crater]

{{Impact cratering on Earth}}

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