Updated 12th, 21st February 2016
This resurgence is found on the east side of the Hoyo Mortiro, north of the sink entrance to the Mortiro-Equileña system and one of two springs into the depression. (The other is site 4273.)
In November / December 2015 and January 2016, water traces by Peter Smith and Terry Whitaker using optical brightener proved that water from the Orillón system in Matienzo was the source of at least some of the water resurging at the Esquileña resurgence on the outskirts of Riva. A positives were also seen at this resurgence, 4272. Further details of the water traces is found on the Orillonzuco page.
It may be that site 4272 is the primary resurgence for both Orillón and Coverón but further water tracing is required.
During an optical brightener test from site 3884, detectors were placed here from 13th February 2016 and checked over the next few days in rising and falling flood conditions. The results were consistently negative. The optical brightener came through at the Jivero 1 resurgence after 48 hours. (The full details can be found here.)
References: anon., 2015d (autumn logbook); anon., 2016a (January / February logbook)
Entrance pictures : yes
Underground pictures :
Detailed survey : see Cueva de Mortiro, site 5
Line Survey :
On area survey :
Survex file :