Rivière Souterraine de la Clapisse

The cave's profile follows a curve, almost vertical at the start, then decreasing in slope until it becomes nearly horizontal. The general direction of the system is N-S. The fossil network, down to -100, remains in this alignment. The active network describes a wide loop towards the East, returning in line with the fossil part. The two networks are linked by a series of tight passages. The variety of orientations in the terminal part of the cave suggests that we are in a fracture zone, beyond which, if the shaft at the sink can be passed, larger conduits may perhaps be found.

Depth: -118 m. Vertical extent of active network: 510 + 130 m upstream unsurveyed. Vertical extent of fossil network: 240 m. Total vertical extent: 880 m.

The great climb is a large decorated gallery (7 X 3), with a small side complex containing a hanging sump, and pretty speleothems. Progress through the very clay-filled gallery is sometimes decorated; after the passage, in opposition above a P3 at the bottom of which the stream flows, one climbs a clay slope and very slippery calcite blisters. The small chamber to the South is decorated.

The active network: after a final vertical tight passage, very delicate on the way up, one reaches the stream. To the North, the gallery rises in a very narrow, sinuous meander for 15 m to emerge in a chamber 5 x 7: an inflow of water is noted there. At -103, one emerges into the gallery, which has become wide again; the stream disappears into a gravel bed. At -111, the stream is regained and followed first through a series of steps and gourds, then in a nearly straight gallery (1.50 X 15), cut by small pools. At -112, the gallery divides: to the left, a low gallery with a temporary sump; to the right, an upper gallery dropping back into the sump gallery 10 m after the sump. In the active sink network, 5 m after the sump, a new fork: in the right wall, one descends into a very narrow joint (0.25 x 3), S-W for 15 m; after another change of direction (MNE), a series of gourds: the stream falls into a 2 m pit-sink and disappears into an impassable tight passage; a dig is planned. Bottom at -118 after a difficult tight passage over a sumped pool.

Enlarged entrance 2 x 1, in an N-S joint: we enter the first part. The fossil network is a complex of large upper or lateral galleries, communicating with each other by shafts. At -10, P6 and 15 m lower down, narrow start of 2 lateral galleries joining at -35 (left gallery) and 48 (right gallery) the main network; the full junction is impossible because of impassable tight passages. At 48, arrival at a P14 in a joint: beyond the P14, an upper gallery continues and communicates at -55 and -60 by shafts with the lower level; at the bottom of the P14, arrival in a sloping chamber 10 x 6 at the end of which is the passage of the "Sloping slab" (in the ceiling, a chimney rises to the upper level (-55)). The gallery descends (25° average slope relative to the horizontal), of fine section (4 x 3), very clay-filled. At -83, to the right, a 20 m chimney whose climb is to be continued. At -90, stop at a calcite barrier and clay fill. Below, to the left, a short uninteresting side passage; to the right, continuation of the cave by a system of crawls. The crawls: the system is complex, a series of very severe vertical and horizontal tubes, superimposed, in the same N-S joint. At -95, very narrow start of the unsurveyed upstream network: 130 m of relatively narrow meander. To the South, awkward progress for 15 m in a meander to a small decorated chamber; in the right wall, a small chimney gives access to the great climb: large decorated gallery (7 X 3), very ascending (up to -65), with a small side complex containing a hanging sump, and pretty speleothems; stop at -65 at a flow of clay and calcite. From the small chamber, one must squeeze into a series of forced conduits and laminar passages where water flows (the "bathtub" passage), S-E orientation. At -103, one emerges into the gallery, which has become wide again; on the left, a very important lateral gallery is noted (17 x 3), clay-filled, ascending and filled in at -93. One then travels roughly horizontally, in the very clay-filled gallery, but sometimes decorated. After the passage, in opposition above a P3 at the bottom of which the stream flows, one climbs a clay slope and very slippery calcite blisters. At the top and to the left, a fine ascending gallery; at the end, a chimney has not yet revealed its secret. At the top and to the right, descent into a joint (S-W), and at -111, the stream is regained. The classic network: beyond the start of the active sink network, the gallery rises, then descends, bending sharply towards the South; bottom at -117 in a boulder zone. At this bend, the delicate climb of a C5 and the passage of a forced conduit lead to a P3 dropping into a fine ascending gallery (W), for 20 m up to -92: calcite plug. At the bottom of the P3, a passage between the blocks opens into the ceiling of the N-S gallery, stopping at 117.