Editing County Fermanagh (section)

===Geology===
The oldest sediments in the county are found north of Lough Erne. These so-called [[red beds]] were formed approximately 550 million years ago. Extensive [[sandstone]] can be found in the eastern part of the county, laid down during the [[Devonian]], 400 million years ago. Much of the rest of the county's sediments are [[shale]] and [[limestone]] dating from the [[Carboniferous]], 354 to 298 million years ago. These softer sediments have produced extensive cave systems such as the [[Shannon Cave]], the [[Marble Arch Caves]] and the [[Caves of the Tullybrack and Belmore hills]]. The carboniferous shale exists in several counties of northwest Ireland, an area known colloquially as the [[Lough Allen]] basin. The basin is estimated to contain 9.4 trillion cubic metres of [[natural gas]], equivalent to 1.5 billion [[Barrel (unit)|barrels of oil]].<ref>{{Cite news|url=https://www.irishtimes.com/news/what-s-your-fracking-problem-1.594199|title=What's your fracking problem?|newspaper=The Irish Times|access-date=6 May 2018|archive-date=28 June 2018|archive-url=https://web.archive.org/web/20180628182751/https://www.irishtimes.com/news/what-s-your-fracking-problem-1.594199|url-status=live}}</ref>

The county is situated over a sequence of prominent faults, primarily the [[Killadeas – Seskinore Fault]], the [[Tempo – Sixmilecross Fault]], the [[Belcoo Fault]] and the [[Clogher Valley Fault]] which cross-cuts Lough Erne.