Tresviso Caves Project

Tresviso Caves Project Gazetter

T91B: RCA6

(El Lago, Pepita)

Area:Mazarrasa Mines
East, North:360534, 4785659 (nearby)
Coordinate Quality:GPS
Long, Lat:-4.7169287475509, 43.210806604168 (map)
Elevation (m):1766
Length (m):730
Depth (m):-69
System:Sistema Ramazosa
Active Lead:
Survey Available:


Obvious mined adit in Pozo de Andara (Lake Depression) . The first spoil heap on the left as you enter the Lake Depression proper Approaching from Caseton de Andara, heading into the Pozo de Andara (Lake Depression), where the track forks at the start of the depression: T105 - Los Italianos (connects to Sistema Ramazosa) T144 - Rosario (connects to Sistema Ramazosa) T91B - El Lago / RCA6 (connects to Sistema Ramazosa) Blenda II Pendiente El Queso Entrance


The lake is flanked to the south by a steep, flat-topped slope of spoil. From the top of the spoil slope, a steep, snow-blocked gully leads straight up the side of the impending ridge. From the northern side of the valley this gulley can be seen to be a major fault line continuing beyond the mine workings on the ridge-top, and over the next ridge. Where the fault-gulley meets the spoil slope lies an elongate, steep sided doline blocked by a snow-plug (even in mid-July). A traverse around the north-eastern wall of the snow-plug ends at a mine entrance 1.5 metres square and part-blocked by rock falls from the gulley above. Entrance


Inside, 15m of horizontal mine passage leads to a hole in the timber and rubble false floor. Two bolt belays allow descent of this first 6m pitch. A short passage leads to a second pitch impressively decorated with a rickety snow slope suspended from the snow plug of the entrance doline.

Pitch 2 begins with a 2m drop onto a flat ice flow supported on gravel and boulders, and bisected by a water channel. The ice flow bends into a curtain leading, after a further 2m drop, to a rotten snow platform. The pitch continues for 12m past a very loose boulder slope, and ends in a snow pit.

The mined rift passage continues across a frozen pool to the head of a pitch. Across the pitch is an impressive eroded ice formation, the Ice Palace.

Pitch 3 begins with a loose boulder-slope which soon gives way to a fine 20m free hang which can be climbed for the first 6m. Below, a short boulder slope leads to a 2m drop into a draughty mine passage.

To the south-east, a series of progressively more interesting 'aerial walkways' lead to a collapsed section which may be crossed on a dubious timber 'tightrope' above an unpleasantly large drop (approx. 40m). This passage follows the fault line, passing an impressive 18 metre natural shaft (undescended) and terminates in a partially explored vertical maze of ladders, walkways and passages. The maze would pitch repay careful exploration, as several small natural passages are intersected.

Moving north-west from the bottom of pitch 3, a short traverse around a 13m pitch leads to a downward sloping passage filled with the roar of water. 2 short climbs, followed by a duck under a waterfall lands back into the fault rift. A short fourth pitch (4m) leads to a wet, tight rift pitch. Fortunately a traverse can be made to a rickety miner's platform from which a pleasantly dry free-hanging 22m pitch is descended. A rush back through the spray leads into another mine passage which, by following the water and/or draught leads to the impressive natural Spiral Staircase aven. This aven is about 38m high and developed largely in white-veined black marble. The floor is littered with miner's debris rusting rail trucks, pipes, timbers and spoil. The Spiral Staircase connects at the top to the T91 Lower Caseton de Andara Mine level.

To the north the aven closes down to a narrow rift widened by mining, which eventually becomes too tight. Halfway along the rift, a short climb on the east side leads to a second impressive natural aven. Unfortunately, this too is choked with spoil .


Minas de Mazarrasa schematics (1974)
L.U.S.S. (1974-1977)