105 Cueva de Riaño (Cueva de Riaño 1) (Cueva de la Reñada)
Riaño VP51900049 Alt. 175m
Part of the Sistema de Cuatro Valles (length 42853m after summer 2000) Depth 92m

Updated 19th February , 18th April 1999; 16th September 2000

Incomplete description

The most northerly entrance into the Four Valleys System (line survey). A route through into Cueva de la Hoyuca (107) exists - and ultimately to Cueva Llueva (114) and Cueva de Carcavuezo (81). The depth is taken to the downstream sump in Cueva Llueva.

The strongly draughting entrance lies in a tree lined depression next to the track. The passage starts low and passes an earth run-in on the left. After 50m a small inlet is met from the right and the way on follows this water and gradually increases in size. Some 200m from the entrance the stooping passage breaks out into a larger area with holes in the roof. At this point it is possible to climb back over the direction of the entrance passage and follow a small dry sandy passage which leads to Double Barrel Passage via Grey Rock Chamber and also to the passage which, in 1993, was smoke tested to Dormouse Cave (935) and the surface. Continuing straight ahead however leads within 20m to a 7m pitch which is best laddered. A few metres further on and the main stream is met and the passage size increases at Eureka Junction.

Downstream the passage is 2m wide and 4m high and runs for 100m until cascades of 2m, 3m, and 4.3m are met. At the base of the last of these the stream runs off to the right and the passage lowers to a crawl. This does not last long and after a further 200m of easy going, another pitch of 8m is met with an awkward crawl at the bottom. The cave sumps 200m from this point and is then some 500m from its resurgence (575).

Upstream from where the entrance joins, the passage has some deep pools until a step up is possible and the stream the flows across a sandstone floor. This can be followed round several dog legs and becomes narrow before reaching a complicated joining of ways. To the right an ascending 2m diameter tube heads back to Grey Boulder Chamber and the entrance. Straight ahead is a quite large inlet and this can be followed into The Mazeway, a very complicated set of narrow rifts which total some 500m in length. Through this area the passage increases in size and after 150m reaches a draughting choke which appears to be only 40m from the surface.

Back at the complicated junction the main stream can be followed in a low and wet passage to the left. There is however a dry and larger route up to the right. These two passages now continue in a straight and parallel fashion for over 200m (Double Barrel Passage). The passages eventually unite and an inlet is met on the left. Just after this two large swirl domes are passed as the passage starts to divide. On the right a walking passage leads to two draughting avens and is not completely explored. Straight ahead a "coffin level" type of passage becomes too tight after 120m. To the left a large sandy floored passage passes under a number of avens (one of which connects with the Upper Series) and after passing an area of broken calcite, becomes a hands and knees crawl. "Cat" prints are visible in the mud at this point. After 40m Cat Print Passage ends in a muddy chamber and a 2m awkward climb leads to the base of an 8m high aven. This can be free climbed up a narrow slot and is the original way into the Upper Series. At the top of the pitch a number of small passages lead off and all appear to rejoin the main passage further to the southwest.

The main passage in this direction is an impressive phreatic tube varying between 5 and 10m high and wide. A passage on the right becomes too small at a choke though there is an alternative way back to the main passage by traversing round The Pit, a large hole which has not been descended.

Continuing in the main passage through a flat roofed area the passage gains height and width. After an awkward climb over boulders another passage is met coming in from the right. This is very well decorated and splits after 50m at the base of a 3m climb. The right branch is choked by stal after 120m but the left branch although smaller has not been explored to an end.

Back in the main passage the lofty gallery continues for some 100m until an inlet is met from the right. The passage now closes down to a miserable flat out crawl in the stream with a calcited choke above. The strongly draughting crawl has been connected to the Second River Inlet in Cueva de la Hoyuca (107). The inlet on the Riaño side of the connection has been followed to a high rift passage which after 200m finishes in a high aven and a choked chamber at a lower level.

Grov write up

In 1991 the downstream passage was pushed to major extensions which needs writing up by Paul Stacey etc. In this area, near the end of the downstream passage some 46m was surveyed in 1992. The inlet passage splits into 2 smaller inlets about 30m from the main passage. Both go to major choked areas. The right hand inlet has been followed into the choke for about 30m.

About 15m further downstream on the left is a steep boulder slope to a climb up boulders into a chamber on a fault with two avens in the roof. The inlet passage across the chamber has been followed along walking passage to a low crawl and choke. None of this 91-92 extension is on the graph survey.

At Easter 1993, a pitch was descended on the right hand side of the main passage, some way from the Anastomosis climb.

L. Mills located individuals of Cantabroniscus in 1985.

References: anon., 1974b (logbook); Cope J, 1974; anon., 1974a (survey); Fernández Gutiérrez J C, 1975; Kendal Caving Club and Manchester University Speleological Society, 1975; anon., 1976 (logbook); Cope J et al, 1976; Mills L D J, 1981; Manchester University Speleological Society, 1982 (survey); Mills L D J and Waltham A C, 1981; Corrin J S and Smith P, 1981; anon., 1984 (logbook); anon., 1985b (logbook); Corrin J, 1986; anon., 1986 (logbook); Corrin J, 1987 (survey); material in file; anon., 1987 (logbook); Cawthorne R, 1987; Corrin J and Knights S, 1988; anon., 1988 (logbook); Davis J and Corrin J, 1989 (photo); anon., 1989 (logbook); anon., 1991 (logbook); Corrin J, 1992a (survey); anon., 1992b (logbook); Cawthorne B, 1992; Corrin J, 1992b (survey); anon., 1993c (Easter logbook); anon., 1993b (logbook); Fernández Ortega F, Valls Uriol and Maria del Carmen, 1998; García José León, 1997 (survey); Corrin Juan, 1997c; anon., 1999a (Easter logbook);
Entrance picture : yes
Underground picture(s):
Detailed Survey :
Line Survey : 4 Valleys System line survey
On area survey :
Survex file :