Trou du Bœuf

The very narrow entrance results from a clearing. It opens immediately at the top and on the side of a gallery about ten meters wide and steeply sloping. At -12, the gallery becomes horizontal. The floor is then covered with a thick layer of clay where a small ravine winds. The gallery's dimensions stabilize at about 4 m x 3 m, the height momentarily reaching 5 meters in the middle section.

Before that (40 meters from the entrance), on the left, an ascending gallery develops after a low, barely visible passage. It widens immediately, extremely clayey, and rises to elevation 0 where it flares into a fine rotunda. A difficult climb allows passage over a large step. The gallery continues and ends in a series of fine chambers (up to +38).

The main gallery continues another 10 meters to the northwest, then turns west. 25 meters further on, it drops abruptly from -14 to -28, the lowest point accessible in October 1967 after a long dry period.

Sump 1 (30m / -7m) blocks passage to the rest of the cavity. Sump 1 is followed by 270 meters of fairly vast, muddy gallery, crossing a chamber after 80 meters and then describing a large sinuosity up to sump 2 (100m / -20m; constriction in the first part). An air bell precedes sump 3 (120m/-13m).

The walls of sump 1 are encrusted with a thick layer of cream-colored calcite, visibly heavily eroded by flood currents. It is likely that it was long a simple pool before the cave became active again.

The cave resurges after exceptional rains. Its origin is unknown, as are the minimum and maximum flows. During years of great drought, such as the summer of 1985, when the Siagnole is completely dry upstream, water appears between the blocks of its bed, starting opposite the Trou du Boeuf, with a flow of about ten liters per second. This is very certainly the low spring of this system. The approximate flow at the entrance during the flood of 06/11/1966 was 1000 liters per second.

On 28/12/1971, a dive allowed passage of sump 1. Sump 2, explored over 100 meters on 23/01/1972, was passed on 03/01/1981 by the Darboun Ragaïe. Sump 3 was passed the same day.

Roots run along the walls, indicating proximity to the surface. A clearing by the Club Martel Nice on 21 August 1972 (guided by the flight of a fly) broke through to the outside very quickly. However, this second entrance is very difficult to access from outside because of the rugged terrain and abundant vegetation.

Guillaume CHARDIN - CDS83, Fichier des cavités du Var > "Trou du Boeuf" (number 1080006): http://www.fichiertopo.fr/display.php?details=true&indexid=1958