Del Malo

The Bolumburu pit has a development of a hundred metres. The entrance, of narrow dimensions and with a rounded cross-section, gives rise to an initial gallery running SW. At 11 m from its start the gallery changes appearance and is cut perpendicularly by a joint running NE. On the left side of this joint opens a crawlway of considerable width despite its low height, and at its end a new crawlway of reduced dimensions opens. Also on the left side a small vertical conduit opens, which places in two drops into a NW joint of medium amplitude with a false floor of clastic blocks; this joint ends at 8 m, cut by a perpendicular with a base of unstable blocks and a vertical at 5 m from its start. In a NE direction the gallery continues for 15 m.

Along the whole route of the cavity upper chimneys are seen with large flowstone that attest to the fall of water through them.

If one continues along the initial gallery one comes upon a crawlway 5 m long and 0.8 m high, which ends in a 2 m drop and connects with a lower joint choked by blocks at its two possible points of continuation. Returning to the crossing of the NE joint, this ends at 9 m; along its left side one continues through a crawlway of considerable width for 8 m until reaching its end, which is the entrance to a new crawlway of reduced dimensions. Through the small vertical conduit on the left side one descends 20 m, locating at -12 m a ramp platform by which one descends to that level.