Updated 27th October, 18th November 2001; 26th November 2003; 27th October 2007; 21st December 2008; 16th May 2009; 25th June 2010; 1st February 2011; 19th February, 3rd December 2016; 8th January 2020; 16th February 2022

   The site is approached past the farm then along the upper track where the wood starts. The large entrance is in trees, 50m up the hill, best found by coming off the track to walk up and across the slope just as a large, fallen tree comes into view. The GPS grid reference was taken when there were no leaves on the surrounding trees.
    The entrance leads straight down a leafy slope and enters a large chamber, some 15m high. This has a massive calcite boss in the centre and some fossil formations. A climb down at the back of the cave leads to a tighter drop and a soak away. The southern side of the chamber has pieces of pottery and possible hearths in various, marked, places. There is also a piece of pottery on the north side.
    The site has been investigated by Spanish archaeologists, with a publication (Ruiz Cobo J and Smith P, 1995) analysing sediments. Reference Beta Analytic Inc, 1994 has the results of a radiocarbon analysis of charcoal carried out in 1994. This material was found under supposed 2-3000 year-old pottery and yet the sample was dated to 850 ±70±BP, or between ±AD 1025 and 1290 with 95% probability.
    A test reported by Peter Smith in Feb 96 has an item dated to the 1st century AD and a bovine femur was dated to 2025BC.
    An article in Studies in Speleology - The Prehistoric cave site "Cueva de las Grajas" in Matienzo, North Spain - has photos and line diagrams of the pottery and attempts to piece together the evidence to provide a chronology (Ruiz Jesús et al, 1999). Ruiz Cobo Jesús and Smith Peter et al, 2001 suggests that the urns were part of a Bronze Age ritual deposit.

Ruiz Cobo Jesús and Smith Peter, 2003 has a useful summary with a survey (pp50-51), and various photos and drawings scattered through the volume. The pottery has been compared with the assemblage in site 2139. (Smith P, Corrin J & Ruiz Cobo J, 2008).

Ruiz Cobo Jesús et al, 2008, p132 gives a date of 1800 BC for the 4 pots. Charcoal has been dated to Roman and medieval. Ruiz Cobo Jesús and Muñoz Fernández Emilio et al, 2009 compares "Orza" type pottery with other finds in the Asón region.

Reference Smith P et al, 2015 has a table of radio-carbon and thermoluminesence dates.

References: Corrin J S and Smith P, 1981; anon., 1994a (Easter logbook); material in file; anon., 1994b (logbook); Beta Analytic Inc, 1994; Ruiz Cobo J and Smith P, 1995; Ruiz Cobo J and Smith P, 1997; Smith Peter and Ruiz Cobo Jesús, 1999; Ruiz Jesús et al, 1999; anon., 2000c (Summer logbook); Ruiz Cobo Jesús and Smith Peter et al, 2001 (includes diagrams and line drawings); Ruiz Cobo Jesús and Smith Peter, 2003 (survey); Corrin Juan and Smith Peter, 2007; Smith P, Corrin J & Cobo J R, 2008; Ruiz Cobo Jesús et al, 2008 (survey and drawings); Ruiz Cobo Jesús and Muñoz Fernández Emilio et al, 2009; anon., 2010b (Easter logbook); Ruiz Cobo J and Muñoz Fernández E, 2013; Smith P et al, 2015; Smith Peter et al, 2016; anon., 2022a (January, February logbook)
Entrance picture : January 2022
Underground pictures: From about 2000; January 2022
Archaeology : drawings of 4 of the 5 pots discovered
Video: Easter 2010 : wmv (6Mb) : mpg (52Mb)
Detailed Survey : 1:500  showing archaeological sites (from Ruiz Cobo Jesús and Smith Peter et al, 2001)
Line Survey :
On area survey :
Survex file : yes (Coordinates altered to fit ETRS89 datum, April 2014.)