XXI.— Age-Relations of the Epigenetic Mineral Deposits of Britain

Finlayson’s thesis that the important British non-ferrous mineral fields were mineralized in Hercynian times is examined in the light of investigations made since 1910 and largely confirmed. It is suggested that hydrothermal fluids leaked into the Zechstein Sea and that dolomitization related to this sea preceded non-ferrous mineralization in the Southern Pennines. Pockets of “fossil” Hercynian hydrothermal waters are believed to explain certain instances of weak mineralization affecting Mesozoic strata. In Carboniferous Limestone areas deep cavernization later than the Hercynian non-ferrous epoch occurred before or during the accumulation of the ferric (haematite) ores in Tertiary times.