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La Verna is part of the {{convert|86|km|mi|adj=mid|-long}}, {{convert|1410|m|ft|adj=mid|-deep}}, {{ill|Gouffre de la Pierre-Saint-Martin|vertical-align=sup|fr}} and Gouffre des Partages cave system which has fourteen known entrances.<ref>{{cite web |title=Naissance d’un géant – Spéléo Tritons|url=http://clan.des.tritons.free.fr/blog/?p=155|website=clan.des.tritons.free.fr}}</ref><ref>{{cite web|title=Les cavités les plus longues|url=http://s391384129.onlinehome.fr/arsip/index.php/synthese/58-les-cavites-les-plus-longues.html|website=ARSIP|publisher=L'Association de Recherche Spéléologique Internationale de la Pierre St Martin|accessdate=20 April 2016}}{{Dead link|date=February 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite web|title=Les cavités les plus profondes|url=http://s391384129.onlinehome.fr/arsip/index.php/synthese/59-les-cavites-les-plus-profondes.html|website=ARSIP|publisher=L'Association de Recherche Spéléologique Internationale de la Pierre St Martin|accessdate=20 April 2016|url-status=dead|archiveurl=https://archive.today/20161125095539/http://s391384129.onlinehome.fr/arsip/index.php/synthese/59-les-cavites-les-plus-profondes.html|archivedate=25 November 2016}}</ref> Explorations still continue in this and in other systems within the extensive Pierre-Saint-Martin [[karst]] area where 13 underground rivers and a total of {{convert|288|km|mi}} of passages, chambers and shafts have been mapped.<ref>ARSIP INFO Edition Spéciale "Les Traversées de La Pierre-Saint-Martin" p.15 - 2014</ref><ref>{{cite web |author=Alexandre Pont and Paul De Bie|url=http://arsip.fr/documents/Synthese.PSM.2021.00.Tirage.A0.Vue.Generale.Detaillee.pdf |title=Synthèse générale des réseaux du massif de la Pierre Saint Martin |accessdate=2022-01-26 | date=December 2021 | publisher=ARSIP}}</ref>
Most of the Gouffre de la Pierre-Saint-Martin is formed by dissolution in [[Cretaceous]] [[limestone]]s, and the main river reaches a [[base level]] where it flows over insoluble [[schist]]s of the [[Paleozoic]] [[basement rock]]s. The Salle de la Verna has formed where the river flows off the schist onto [[Devonian]] limestone. Over time, the river found a route through the soluble limestones, leaving the original downstream river passage (the Gallerie Aranzadi) high and dry. The chamber was formed by a process of solution and collapse, beginning about 200,000 years ago.<ref>{{cite book|last1=Maire|first1=Richard|editor1-last=Gunn|editor1-first=John|title=Encyclopedia of Caves and Karst Science|date=2004|publisher=Fitzroy Dearborn|location=New York|isbn=1-57958-399-7|pages=1252–1255}}</ref> The unconformity between the Paleozoic and [[Mesozoic]] rocks is clearly exposed in the walls of the chamber.<ref>{{cite web|last1=
The river flowing through the chamber originated from the infiltration zones on the {{convert|2000|m|ft|adj=mid|high}} limestone plateaus, and emerges at [[Spring (hydrology)|springs]] {{convert|1500|m|ft}} lower, in the valley of Saint-Engrâce.<ref>Jean François PERNETTE – « Rivières sous le Pierre » - F. Nathan – 1983</ref>
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