Tresviso Caves Project

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T154: Cuesta
Area:Mazarrasa Mines
East, North:360668, 4785503 (nearby)
Coordinate Quality:GPS
Long, Lat:-4.7152404755648, 43.209427213221 (map)
Elevation (m):1835
Length (m):422.91
Depth (m):0
System:
Active Lead:
Survey Available:

Approach
From the Pozo de Andara (Lake Depression) take the first left track up towards the Mazarrasa mine area. Follow the track into the large, flat floored depression riddled with mines, many surrounded by green fences. Cuesta lies in the back wall of the depression just above the floor and is labelled in red with CUESTA.

Entrance
Cuesta lies in the back wall of the depression just above the floor

Description
The entrance quickly leads up over a small rock pile to an opening to the surface 8m above. A significant draft is evident at this point and throughout the cave (follow the draft at each junction!). The rock pile drops back down to re-enter the obvious mine adit. The mine passage continues in a southerly direction for 90m, in a 2m x 2m passage. Part way along, on the left-hand wall, is a small climb into a rift like passage to a natural passage descending to a pitch, with the possible sound of water below. This has not been explored but is noted in the Tresviso 1979 journal as 10m deep and blind.

Continuing along the main adit an obvious aven enters on the right, with a trickle of water. The aven is a 3m climb (not explored) and appears to head south, in a tight rift parallel to the main passage.

After 12m the passage reaches a junction. The right-hand branch, is 30m, passing some small pools to a dead end. The left-hand branch heads east for 50m to anther junction.

Straight on leads immediately to a collapse of mine deads. It is possible to crawl over the top of the deads, but the passage quickly ends at a further collapse. This would appear to have once been connected to the ELENA mine entrance (1970's R.C.A. mine schematic).

Turning right leads after 17m to another junction. The right-hand junction leads to 80m of passage and a dead end. The left-hand route continues to follow the draft for 80m before an obvious pitch on the right is encountered. The pitch head appears unstable and there is evidence of an old winch platform. The pitch is approximately 15m down a ramp and connects partway up Plank Pitch.

5m past this first pitch an obvious pitch / rift across the mine passage is encountered. The remains of an old wooden bridge are present and appears unstable. The pitch, Plank Pitch, drops down 30m to a lower level, passing a ramp connection with the winch platform pitch in the main adit. The pitch lands in the lower mine levels with water dripping in from the ceiling.

Down from the pitch bottom a short (2m) climb leads to 8m of false floor passage with a winch shaft coming from above and no way on. A lower level, immediately below the climb appears to be flooded, dropping suddenly from thigh deep water into a very deep blue pool. No dry continuation or natural was found so the pitch was derigged. Up from the pitch bottom leads to a short, wet section and a blank wall.

Back in the main adit the wooden bridge can be traverse safely with a handline on the left-hand side. After a sharp left bend the passage continues in a straight line for 25m, before another sharp left-hand bend. 10m further on the passage doglegs right to 30m of passage, passing through a large mined out chamber, with platforms and stemples in the roof.

A strong draft is evident, and this is the high-level route back up to the T123 ROSA mine levels. There is an obvious surface feature, directly above this at 0360845 4785333 1956m that is worth investigating.

Just before the chamber a passage on the right, heads back towards the Plank Pitch area, descending steeply to further winch platforms. This has not been descended and is assumed to connect to the lower levels. A voice connection was made but any physical connection appears to be beyond old and unstable mine workings.

At the far end of the chamber the passage turns left and heads north east for 80m to a dead end.

Reference
L.U.S.S. (1979) (Explored by Kingswood)
T.C.P. (2018 - 2019)

Images
Entrance Schematic