Grotte de Lacalm

One enters on level ground into a fairly vast chamber lit by daylight (average height 2 metres). It continues as a corridor slightly narrower that turns sharply to the east-northeast and emerges outside through a small opening, impassable, in the form of a vent (distance between the two openings: 40 metres approximately).

From the entrance chamber a small dry gallery branches off toward the south, narrow and winding, about a metre wide, which ends in a dead end after 28 metres. In the bent part of the corridor leading to the vent and on the same side as the Bat Gallery there is a small tortuous crawlway, quickly impassable.

About seven metres northwest of the Bat Gallery, several very low openings along the wall give access to a second chamber situated at a slightly lower level (total length: 20 metres, width 4 to 6 metres, height: 1.5 metres approximately). This very irregular, uneven chamber is cluttered with sand and stony alluvium; the floor and the vault show some collapses.

The Bat Gallery is slightly decorated with speleothems.

Toward the back of the lower chamber flows a perennial ruisseau souterrain (water temperature: 13°). It can be followed for only a few metres in a quickly impassable rolling-mill gallery; several small passages give access to it. At the entrance of the lower chamber, a network of small narrow galleries, sometimes strongly eroded, also allows one to reach the underground watercourse, which partly infiltrates among the gravels. One of its former beds is still clearly visible in the chamber.

grotte de Lacalm was carved by the ruisseau de Courbas, which descends from the Montagne Noire and disappears at the contact of the limestones of the Causse, at 200 metres.

The whole part of the cave comprising the entrance chamber, the corridor toward the vent and the Bat Gallery is dry and dead.

Source: MAGNÉ Jean & MAGNÉ André, « Spéléologie du Causse de Labruguière », pages 132-137 (offprint pages 2-7): http://asnat.fr/pdf/SpeleoLabruguiere_Magne.pdf ; page 136 (offprint page 6): http://asnat.fr/pdf/SpeleoLabruguiere_Magne.pdf