The exploitation of a gold mine of alluvial origin needed large amount of water as the sand, which contained the metal as dust or nuggets, had to be "washed". The procedure, was digging the sediment made of sand and pebbles of different sizes that, gathered and put aside, formed the big piles that now represent the Bessa landscape. The sand was then poured into channels (provided with wainscot with weak and constant slope) where the water flowed together with gold, magnetite and garnet (whose specific gravity was higher and could then deposit quicker) and finally collected through different procedures. A second washing, probably with the classical "plate", still used today by gold prospectors in Elvo stream, separated gold from the other minerals. The sediment so deprived of metals was thrown off the slope, towards Elvo (and in the southern part of the Terrace also towards Olobbia) forming cone dumps. The water for this operation came from Viona stream and was directed into a channel probably parallel to Bernasco-Vermogno moraine.


channel in the upper terrace    



   channel in the cone dumps


The water distribution network, gathered by the above-mentioned channel, appears still today through several deviations crossing the Terrace that seem to fill natural streams, previous to the mine exploitation. Many of these channels, widen during their course, or more often at the apex (west), into wide flat surfaces slightly leaning towards the plains, totally or partially surrounded by dry masonry, often funnel-shaped, and where it is likely that during the night water was collected for using it during the working hours. These products kept very well until now (with enlargements and subsequent restructurings) as the surfaces, reclaimed and flattened, were suitable to be exploited, once their original function was completed. In some of these basins the feeding channel is still visible.

Aerial view (South East)

Upper part: piles of pebbles crossed by channels

Lower part: cone dumps

The water distribution network cannot be easily identified in the south-west part of Bessa (between Cascina dell'Apostolo and Cerrione) as a high number of depressions, where channels should be inserted, present signs of roadways, irregular slope bottom, interruptions against piles of pebbles or internal slopes of the Terrace.

Several springs, active or dried, are inside the Terrace and along its edges and represent the visible "terminal" of the water, which, infiltrating into the piles, runs through the troughs or gathers into impermeable depressions. The good condition of the protections made of semi-circular or rectangular pebbles masonry, with leaning floors or steps heading to deeper ones, proves the accurate maintenance done up to now.




Bessa after exploitation

(da F.Gianotti)  

 Roman mine