0106: Riaño, Torcón de
Riaño 30T 452184 4799245 (Datum: ETRS89. Accuracy code: G) Altitude 265m
Length 120m Depth 95m
Area position

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

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.

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 below 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.

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
Entrance picture :
Underground picture(s): entrance slope and pictures from the 2004 exploration
Video : (by Juan Corrin) Entrance rift    Walk down to pitch head   Rigging 1  2  pitch head  7m shaft top  echo at p93
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 : yes (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