As Moracas is the toponym that designates a large area in which the Ancient mining of a glacifluvial deposit occurred. It stretches 6 km, with a width that varies from 50 to 250 m. Downriver, it hooks up with the other mine of As Fontes/ Los Entralgos, while upriver it also connects with Los Castros/ Las Cavadas, near the confluence of the Seco creek.
A glacier eroded hard rock gold mineral and dragged and deposited it down the valley. As it retreated during the Holocene it was substituted by today’s river network which, in turn, also eroded the glacial deposits. Thus, the gold is found in a secondary position, having been moved by two natural processes. In the Roman period the whole valley was mined for gold, resulting in the tapping and washing of all gold ore. As a consequence, the topography of the valley floor was greatly transformed.
The river network allowed the washing of placer gold by doing minor changes in the course of the water, small deposits or washing channels. The valley gradually grew deeper and most of the fine tailings were washed downriver by the Ancares River itself, while the heavier tailings, boulders and larger stones were moved aside, forming the characteristic large heaps which have provided this part of Candín with a name: As Moracas.
Only small parts of the gold deposits have remained untouched, possibly because of the low proportion of gold. They remain as solitary outcrops, bearing witness to how mining changed the land, as in the case of the Teso de Altamira.
The gold mines in north-western Italy, La Bessa, were exploited in a previous stage by Rome, before control over the Hispanic northwest had been secured. They are also glacifluvial deposits, and the techniques seen there are clearly also at use later in the Ancares.