I also have been following the cuevasdelason.canalblog.com
. It's not the easiest site to navigate (not as good as Matienzo Caves!), and it's not as up to date but it does have interesting indications of what is going on in the Meira-Tejuelo area. My own thoughts for what they are worth, is that we are looking at a regional integrated cave system of extreme size.
Is it too simplistic to think that all the water from the tops above the Ason and Meira valleys has in the past seen considerably greater flows (glaciation at these levels). The water has found its way north and taken every route it could to reach sea level.
It was always thought that the Ason as it cut back from Ramales captured some of this drainage and in doing so removed some of the cave passages heading North. This has left remnents at levels well above the present river levels a good example would be Canyuela on the South side of the Busablado valley and Vallina / Renada on the North side. Surely these must have been part of the same system heading North.
The present resurgence for Cayuela, Cobriamente, is lower and much younger than the old level between Cayuela and Vallina. The french work in Orcones is indicating that there may well be an extensive phreas below the top end of the Bustablado Valley. Molino could be a spill over from this mega phreas and could be fed by present drainage from Tejuelo, Vallina and other stuff over towards the Meira. The main flow may not be going there though and may be going to Aguanaz.
All this is speculation as no dye tests have been carried out as far as I know. The Cayuela, Cobriamente connection has been proved though.
This is of course only considering where the water goes now.
Ali says is the old flow path an "inlet to Matienzo" my thoughts would be yes and to all the caves we already know about to the North also. Renada Vallina Mustajo, Regaton, Toad, Emboscados and all the other bits at this higher level were probably integrated in this South North drainage from the South.
If we move to the NW, and where I think a lot of the present day drainage goes now, Aguanaz, there is not now the thickness of Limestone to support these higher level caves and they have been eroded. What I think we have left in that area (Cobadal, Coimbre) are the lower level younger "Vadose" remnents. This of course doesn't mean there are not long caves to find in that area but the lower we go the smaller they may be.
Ways into the bigger stuff (if the theory is right) might be Hoyon, back end of Toad (that's a thought!) Vaca, Encaramada, Tejuelo and associated big caves and the new cave at Coimbre.
There are a number of dye-tests which would answer some of the questions about present flows but they could be quite hard to carry out and need lots of "dye".
The french are obviously working on the area round Orcones, not much detail on the dives but they seem to have made considerable progress towards Molino, what about the other direction?
I think there is evidence for these thoughts in the NW and plenty of speculation about the Fresnodo, Torno, Uzueka, LLiano, Riano, Vaca set up( another integrated system or part of the same?, to keep us going for a while.
Lets have some comments . Lank