The Early Carboniferous (Courceyan-Arundian) monsoonal climate of the British Isles: evidence from growth rings in fossil woods

The British Isles lay at a palaeolatitude of 4 degrees S during the Early C arboniferous (Courceyan-Arundian) period. This paper examines fossil gymnos perm wood from ten localities in western Ireland and southern Scotland in o rder to analyse palaeoclimate. Fifty-two percent of the 77 fossil wood spec imens studied exhibit growth rings that possess subtle, discontinuous ring boundaries and ring increments of narrow but variable width. These growth r ings are qualitatively and quantitatively analysed, and are shown to bear a close similarity to growth rings in modern araucarian conifer woods; these araucarian growth rings are formed in response to tropical rainfall season ality linked to monsoonal circulation. The findings of this study therefore support earlier palaeoclimatic interpretations, based on sedimentological evidence, which suggest that the British Isles experienced a monsoonal clim ate during the Early Carboniferous (Courceyan-Arundian) period.