200 Millions years ago "Jurassic" (first mammals) limestone sedimentation: the continent of the time correspond to our nowadays "Massif Central", on the edge of it (Angouleme county including Lussac spring) was some limestone reef (corals).
130 Millions years ago end of the "Jurassic", the sea withdraw from the Angouleme county, the limestone was emerged and so subjected to a first erosion.
80 Millions years ago "Cretaceous" (disappearance of the Dinosaurs) the sea came back on the whole Angouleme county.
65 Millions years ago end of the Cretaceous, the sea withdraws finally, followed by an ongoing erosion of the limestone.
The "Font de Lussac" spring was born (crack open) in 1755 following the earthquake of the city of Lisbon (Portugal) ... so only three centuries old !
before the flow was exiting by the "Bouillant" spring at 200m distance on land ... an underwater connection between the two maybe exist, but haven't been explored yet.
1966 M. Seguin -13m
1969 Expedition "Turbidite II" (film) of the Groupement Speleologique Charentais –70m
C. Touloumdjian: 1984 –83m / 1985 -89m in the small shaft / 1986 discover the –120m
1990 C. Touloumdjian, H. Foucart –125m in the small shaft
1997 P. Bernabé, L. Giordano –142m in the big shaft
2001 F. Walter, J. Meynié (film) –125m through the small shaft and in the horizontal gallery. J. Meynié explored 20m at -115m in the downstream gallery
2002 J. Meynié (film) –130m in the big shaft; F. Walter and D. Victorin made the junction between the two shaft at –125m
2003 V. Ferrand explored 40m at -115m in the downstream gallery
2004 J. Meynié (CCR Mk15.5) -160m, and 36 hours after: -180m in the newly explored deep wide gallery, 280m from the surface
