Aven de l'Alabrena - B 16

The entrance doline measures 10 x 5 m; it is an earthy funnel bordered on the East by a vertical wall. At the foot of the entrance, a constriction leads into a small dirty side passage of about 10 m, not shown on the survey. The main gallery is very comfortable in size and even surprising for the region: 8 to 15 m wide, 4 to 6 m high over 50 m long, cut at the contact between quartz sandstone and nodular limestones. Upstream, a low conduit is practically filled with blocks. Following the slope, a first narrowing appears at -20; one immediately straightens up into a fine gallery, a little smaller than the previous one, which is followed for 30 m. The dimensions suddenly shrink; after a small crawlway, one emerges into a new chamber at -30 m, where two passages to the right are choked. a flat-out squeeze is followed, after 10 m, by a small awkward 3 - 4 m step that leads to 10 m of narrow meander.

Following the temporary active stream, one takes a flat-out squeeze.

One descends fairly easily by climbing, the last three metres are vertical. Upstream, a quick dig allowed progress of 35 m more up to + 3 m in a low conduit practically filled with blocks. Following the slope, a first narrowing appears at -20, one immediately straightens up into a fine gallery, a little smaller than the previous one, which is followed for 30 m. The dimensions suddenly shrink, one passes a small crawlway and then emerges into a new chamber at -30 m. Following the temporary active stream, one takes a flat-out squeeze followed after 10 m by a small awkward 3 - 4 m step that leads to 10 m of narrow meander.