CP01

The entrance porch, with dimensions unusual on the Foillis (6 x 10 m), opens onto a steeply inclined névé. Fifteen metres lower, the chamber occupied by a refrozen ice lake is pierced by a tunnel dug into the ice. The bottom is choked by blocks in a fault pinch. One can go around the ice plug (5 m) and even slip underneath it. No possibility of continuation is visible (no draught). Depth -60 m.

It is the abundant inflow of water falling from the ceiling that allows passage through the tunnel dug into the ice. A violent draught blows from a crawlway that we have begun to clear, but explosives would be needed; this will be one of our next objectives.

One must slip into an ice-covered crawlway to emerge beneath the névé. Ten metres lower, one must rig a rebelay on the opposite wall, at the moment when we leave the ice. From there, two possibilities present themselves: 1) descend the vertical (P 15); one then finds oneself between the fault mirror and the névé (l = 1 to 0.4 m), the passage narrowing more and more as one descends. 2) reach the inclined plane of the glacier, which one descends to a chamber choked by blocks.

The entrance porch of the CP1 opens in the Sénonien, 20 metres thick at this point. The traditional Albien layer is here laminated, and it is in the Urgonien that the rest of the cavity develops. The CP01 is dug at the expense of two important compression faults: one perpendicular and the other parallel to the axis of the syncline. Both faults show a significant throw.