MINES, TRIALS AND LODES OF THE GLANDYFI TRACT, CEREDIGION, WALES

摘要

Over most of the Central Wales Orefield the great majority of the lodes are oriented broadly ENE-WSW and extend laterally over considerable distances although economic mineralisation is not continuous along their length.However in the far NW of the orefield many smaller mines, and numerous trials, notably those around Talybont, lie in or adjacent to an extensive fault belt oriented SSW-NNE (Figure 1) which locally contains relatively impersistent subsidiary NW-SE, E-W/ENE-WSW and ESE-WNW lodes. The belt has been termed the Glandyfi Tract by the British Geological Survey (BGS) and its development S of Afon Dyfi is extensively mineralised between the mines at Loveden and Alltycrib (Figure 2). By contrast with the remainder of the orefield the belt was not very productive. This results largely from the complexity of the fault systems and limited extents of ore bodies, some of the best production coming from small, rich and steep 'pipes' near the intersections of lodes of differing orientations or the intersections of lodes with a regional joint system which strikes broadly ESE-WNW perpendicular to fold axes (a-c joints). Recorded post-1845 production of lead concentrates totals about 4,135 tons; earlier production could well be similar or a little larger as several sites were active in the eighteenth century and some are of great antiquity.5 However the returns were very poor for the effort expended and probably totalled barely 2% of that for the entire orefield.