Matienzo - Dowsing for Caves
Juan Corrin & Dr John Wilcock
Over 3 days in July 2011, John Wilcock (supported by Juan Corrin for 3 days and Ian Chandler and Penny Corrin for 1 day each) used his dowsing skill to predict where cave passages (probably with water) might be found. The sections below include the investigated areas, the dowsing reactions found and the hypothesised connections between them. John has investigated a number of areas in Britain and abroad, some with notable success in predicting where "new" caves might be found. He has also written an overview of dowsing for caves. The British Caving Library's audio archive has a 10 minute talk from John about his dowsing.
As only three days were available, a broad sweep of the area to the northwest of Matienzo - the possible catchments for Fuente Aguanaz and the supposed La Gatuna resurgence - was thought to be the most informative strategy.
Technique and Interpretations
Bent wires were used as the indicator for a reaction. These wires crossed as John walked over a cave or underground streamway and uncrossed when he passed out of the reaction. He could, therefore, give a width to many reactions. The width of the reaction is said to be dependent on the width of the water course (or cave passage) and the depth below the surface - the deeper the passage the more diffuse and wider the reaction.
Roads, tracks and open ground were used to follow reactions - the thick undergrowth makes it virtually impossible to sensibly follow dowsing lines. The discrete reactions were plotted on a printed map and then joined by dotted lines giving a proposed path (and possibly width / depth) for cave passage below. The field sketches have been reinterpreted and plotted as a layer on the Matienzo digitised area map. These map sections (pdf files), with the dowsing shown in cyan, known cave centre-lines in purple, a lack of reaction in light red text and scale indicated by small crosses 500m apart, can be accessed through links in the following sections.
A short video can be seen here.
Itinery, Results and Interpretations
The dowsing program, outlined below, has been condensed from logbook entries. Each interpretation is only a possible explanation of what might be happening beneath the surface. Only a very small proportion of the ground was covered, even where a reasonably detailed picture was deduced.
Day 1 (22/7/2011)
The first dowse was at a recently recognised, wet weather resurgence (site 3541) just south of El Camino, west of the main road. John dowsed this up behind the church until the dense jungle. It's heading towards Cueva Coreano (site 137). A small hole (site 3538), not draughting, was also found on the dowsing line. (Result)
A drive to Fuente Aguanaz followed to dowse the upstream continuation. This took about 4 hours, picking up strong reactions at various points on roads, tracks and open fields. The reaction was then traced on the road down to the main La Cavada - Alisas road. (Results and interpretations for the Fuente Aguanaz catchment are shown below in Day 3.)
A quick visit to Cobadal looked at a possible northern route for water from Orchard Cave and Snottite. This reaction is just down the track from the farm at the changing spot for Snottite, directly north of Orchard Cave. (Result). The result may indicate a northern route for drainage from Orchard / Snottite towards Torca la Vaca or, possibly, drainage from the large depression to the north passsing under the ridge to pick up water from the Orchard/Snottite depression then join with the water sinking south of the Cueva de Torcida entrance.
Day 2 (23/7/2011)
The main aim was to search for the "Aguanaz-from Alisas" connection mentioned on the display boards at the Aguanaz resurgence. The day started at the sinks / shafts in the road bend just north of the Puerto de Alisas (sites 2037, 2035, 2036 and 1969). John could find no reaction dowsing up and down the road. (Results). The lack of a reaction may indicate that the water from these sinks heads south, at least to start with. On this fleeting visit, very little ground was covered.
Next. the area of the Duck Sink, site 1976, was visited, where John immediately got reactions in a number of places, eventually "tying in" with the previous days southern upstream limit for Aguanaz, ie crossing the main road, passing under Torca de Michelin (site 3021) and new site 3543 (a choked sink against a 4m high scar by the side of the road), the Duck Sink (with a proposed branch coming in from the north) then heading east under the steep road down from the bus shelter and continuing under the main road and the 2 north-heading roads at the edge of the Cobadal depression. A reaction was also detected near the poly tunnels which headed straight for site 2091, a dig southwest of the sumidero entrance. (Results are tied into Day 1 and 3 below.)
Day 2 finished with John and Penny walking the northern road from Bus Stop Shelter Hole (site 2908). No reaction was detected until the road started to turn and climb out of the depression at a farm. Here, a 20m wide reaction could be from The Sewer. Just above, a 250m wide reaction, along with 2 other wide reactions later found higher up, could be associated with a possible northern route to Aguanaz for the Sumidero de Cobadal water deep underground. (Results) This water has been dye-tested to Fuente Aguanaz.
Day 3 (24/7/2011)
Contrasting with the previous 2 days, overnight rain had soaked the ground and vegetation and waterproof clothing was required at times. Also, contrasting with the friendly farmer about Fuente Aguanaz, the proprietor of a farm in La Gatuna was not happy with people walking across his land, especially when they were searching for caves.
The day started behind the upstream end of site 979, Fuente de Culebro (which is fed by Cueva del Nabo, site 3357) at the northern end of the La Gatuna closed depression. John picked up reactions that suggests the cave soon meets an inlet. Further dowsing took us south into the jungle areas, eventually reaching the depression with the entrance to Cueva de Collada. Note that the farmers at the northern end are friendly but the farmer whose land site 153 (Tree Root Cave) is on is most unfriendly and, despite Ian's negotiations, insisted we left the positive reaction to the west of his farm. All together, the dowsing reactions seem to indicate a system with inlets under the jungle-filled depressions in La Gatuna, with Cueva La Collada as possibly the "top sink". (Results)
The second spot was the farm above the end of the Torca la Vaca Suit Wrecker Inlet. A positive reaction was found over the end of the inlet trending in the correct direction. This "indicates" the survey is reasonably accurate but doesn't indicate a Collada - Cow Pot connection. The farmer here was very interested and jolly having just come back from his pre-lunch blancos.
Returned to Cobadal to dowse along the south side and fill in some details. First drove to the farm yard due west of the poly tunnels. John picked up a positive reaction on the track down. Intending to follow this to the west we entered a field with cattle only to have the bull saunter belligerently towards us so a quick exit was made under the electric fence onto the road. A positive reaction was obtained below the cabaña to the west then further positive reactions which indicated 2 passages coming in from the main depression with Cueva Torcida (site 613). A good sized stream was running down the wooded gulley next to the cabaña but the sink was not seen (due to jungle phobia and fear of the bull).
The complete results for the days spent investigating the Fuente Aguanaz catchment show a number of possible inlets, eg around the Duck Sink and Cueva de Torcida and indicates a possible far source at site 2091.
No definite conclusions can be reached if the reader takes a dowsing-sceptic approach. If the reader believes that dowsing can show underground routes for water (both present and past) then one set of reactions and possible links have been shown on the maps. It cannot be overstated that the dashed cyan lines are deduced from the positions and directions of positive reactions both leading to and from them. Of course, other water routes may join in along these hypothetical lines.
In the end it is up to the reader to use his/her knowledge of the geology and geography of the area, along with these maps of dowsing reactions, to deduce in which caves and digs it might be best to expend most effort.
Torca la Vaca has shown that, despite the relatively low altitude of the hills above, enough depth of limestone remains to hold a number of overlapping levels of development which have occurred in this area. The reactions could be from any or all of these levels.
A more detailed and comprehensive approach to all dowsed areas might prove beneficial. In particular, the dowsing carried out over the probable Fuente Aguanaz catchment shows no inlets bringing water in from Alisas (to support the assertion on the information boards). A systematic sweep of the area to the south of Torca de Michelin and Duck Sink is a future project to pick up this feeder. Possible feeders from the southwest should also be investigated, ie towards the Miera valley.
It may also be beneficial to use dowsing to indicate possible passages radiating from a dig site. There are hundreds of these to check out!