subterranean waterfall

{{Short description|Waterfall located underground}}

File:Ruby Falls.JPG is an underground waterfall within a cave in Tennessee, United States]]

File:Gaping Gill main chamber - geograph.org.uk - 227709.jpg

A subterranean waterfall, tierous waterfall, or underground waterfall is a waterfall located underground, usually in a cave or mine. They are a common feature in cave systems where there are vertical or near vertical geological structures for the weathering process to exploit, and sufficient gradient between the sink and the rising.{{cite book|author=Kevin Adams|title=Waterfalls of Virginia and West Virginia: A Hiking and Photography Guide|url=https://books.google.com/books?id=KOnHiX7xIKIC&pg=PA32|date=1 June 2002|publisher=Menasha Ridge Press|isbn=978-0-89732-414-4|page=32}}{{cite book|last1=Waltham|first1=Tony|last2=Murphy|first2=Phil|editor1-last=Waltham|editor1-first=Tony|editor2-last=Lowe|editor2-first=Dave|title=Caves and Karst of the Yorkshire Dales|date=2013|publisher=British Cave Research Association|location=Buxton|isbn=978-0900265-46-4|page=136}} Notable examples include Ruby Falls, {{convert|44|m}} high, in Chattanooga, Tennessee{{Cite web| title = Tennessee's Spectacular Underground Waterfall| work = The Weather Channel| date = 21 March 2014| access-date = 4 April 2016| url = http://www.weather.com/travel/news/tennessees-spectacular-underground-waterfall-photos-20140321}} and Gaping Gill in the Yorkshire Dales, UK with a fall of 98 metres (322 ft). The highest known subterranean waterfall is in Vrtoglavica Cave in Slovenia, and is at least {{convert|400|m}}.{{cite web |last1=Pavils |first1=Gatis |date=7 March 2013 |title=Vrtiglavica Cave and Waterfall |url=http://www.wondermondo.com/Countries/E/Slovenia/SlovenianLittoral/Vrtiglavica.htm |access-date=4 April 2017 |website=Wondermondo}}