Located near the southern end of Risco de Famara, it is a river valley transformed into an interior endorheic basin after the eruption of the Guanapay volcano. The top sector is currently disconnected from the rest of the valley due to the ravine directly over Risco de Famara. In the endorheic area of the valley, there are levels of paleosol from the Lower Pleistocene era with abundant manganese nodules and anthophora nests fossils. These deposits are used as land on “loan” to be harvested. The volcano of Guanapay is a brown-ochre cone whose summit was used in the 15th Century to build the Castillo de Santa Bárbara, as it was an excellent viewpoint, overlooking the whole central sector of the island and the ideal spot to build a fortress. In order to build it, they used the lava and pyroclast of the volcano. The castle has been refurbished and turned into a museum dedicated to piracy on the islands. The work done to the floor on the edge of the crater stands out (with a rhomboid shape). This volcano preserves its morphology and is crowned by one of the basaltic lava flows. On the inside of the crater there are remains of a rectangular construction. The flanks of the cone are cemented and show gully erosion development.
This geosite has a main geological interest, geomorphological, and also vulcanological, petrological, sedimentary and paleontological. On the other hand, also historical and ethnographical.