0106: Riaño, Torcón de
Riaño 30T 452177 4799241 (Datum: ETRS89. Accuracy code: M) Altitude 258m
Length 407m Depth 95m
Area position

Updated 30th August 1998; 7th June 2002; 8th November 2003; 9th October 2004; 18th February 2012; 9th September 2019

[A previous length was stated as 120m; this should have been 224m.]

The entrance is well hidden in a densely vegetated hole opposite a cabaña. A bouldery entrance slope meets a trickle of water from a pipe which then flows down the pitch. The first drop of 7m is followed immediately by the main pitch of 91.5m. At the base, a narrow vadose streamway sumps after 100m. This is about 50m from the upstream sump in 3rd River Inlet in Cueva de la Hoyuca (107), and they presumably connect. The cave appears on the Cueva Hoyuca and the Four Valleys System Hydrology diagram.
On the left of the entrance slope is a stoop / crawl which splits: the right hand route rejoins the main way on, the left hand route needs to be pushed through a wet crawl. This was surveyed as part of batch 0106-2019-01.1 although the wet crawl wasn't pushed.

A second exploration was carried out on 5th August 2004 using electric light and SRT (not small carbides and ladders) twenty nine years after the first exploration. The sketch shows that there are possible passages on the way down to look at, but no way on over the top of the sump was found.

Fifteen years later, over 3 trips in August, 2019, one of the "possible passages" was investigated. Passing an unexplored passage about 15m down the main pitch, another 35m of descent meets a large stal that can be lassooed to gain solid ground at a ledge. A climb up to the south from here closes in but an exposed, bolted traverse around the shaft to the north and east, over a giant "rock horn" - The King Horn Traverse* - meets a decorated ledge and an open passage. This is also well decorated and, after a short walk, leads to a climb through a stal window to shoulder-width, walking passage. The route zig-zags for 80m past a couple of shield-sized and -shaped stal to a squeeze through a stal grill. Another squeeze, high in the passage leads to a letterbox and drop down into dark limestone with three, 3m high avens off the the left - all too tight at the top. The passage continues as a hand-and-knees crawl for another 20m past an enlargement with sandy banks. At the end, mud and sand fill has been excavated (partly as flexible slabs) for 7m where falling water can be heard and and an inward draught felt. It appears to continue small and quite a lot of digging will be required. [Passage description by Diane Arthurs and Simon Cornhill]

The main pitch rope has been removed for the 2019/2020 winter but the traverse line has been left rigged. The first explorer on the next visit will need to lassoo the stal to get onto the ledge.

* Named in memory of Chris Kinghorn. See this Facebook page.

References: anon., 1975b (logbook); Kendal Caving Club and Manchester University Speleological Society, 1975 (survey); Corrin J et al, 1981b; Mills L D J and Waltham A C, 1981 (survey); Corrin J S and Smith P, 1981; Manchester University Speleological Society, 1982; material in file; anon., 1998d (logbook); anon., 2004d (summer logbook); Corrin, Juan 2006; anon., 2019d (summer logbook)
Entrance picture :
Underground picture(s): entrance slope and pictures from the 2004 exploration : 2019 explorations at -50m in the big pitch
Video : (by Juan Corrin) Entrance rift    Walk down to pitch head   Rigging 1  2  pitch head  7m shaft top  echo at p93
Explorations 2019 - King Horn Traverse and beyond (YouTube)
(Diane Arthurs / Simon Cornhill)
Sketch : main pitch with possible passages leading off. (from anon., 2004d)
Detailed Survey :
1975 known cave low res high res
1980 with Third River Inlet low res high res

Line Survey :
On area survey :
Survex file : 1975 & 2019 (Amended magnetic declination December 2013 to align with Eur79 grid and coordinates altered to fit ETRS89 datum, April 2014.)
Miscellaneous : team for the first exploration in 1975
Hydrology (Terry Whitaker): Hoyuca and the 4 Valleys System

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