In the Mining Region of Bizkaia there has been a process of natural recovery of the old mine-workings, similar to that occurring in other opencast coal mines elsewhere in the Peninsula, but, favored by a suitable climate and the inert nature of the iron ore. The vegetation here reclaims the extraction faces and stints so as to produce a beautiful and harmonious combination between the rock matrix left exposed by mineral extraction, and the trees and bushes clinging with their roots to the very same rocks.

Water quickly fills any impermeable excavations in such a way to create numerous pools and lakes of varying length and depth. Among these lakes, those worthy of note include of the one near to the village of "La Arboleda", as well as others located close to the towns of Sopuerta, Galdames and Abanto y Ciervana. All the features over centuries by the exploitation of iron form the very Backbone of the Basque Country. They constitute a particularly singular element, like no other landscape in the rest of the Country, and legal protection is urgently needed in order to prevent their loss or deterioration.