Alluvial Heavy Minerals as Indicators of Late Pleistocene Ice Flow in the Irish Midlands

Abstract

The alluvial heavy minerals of Slieve Bloom consist of an allochthonous group, glacially imported from the Carboniferous limestone piedmont, and an autochthonous group derived from the Lower Palaeozoic rocks of Slieve Bloom. The spatial distribution of each group is distinct from the other along the river valleys; the allochthonous minerals are found only where till is being fluvialiy eroded; the autochthonous dominate in valley reaches devoid of till. Given this spatial arrangement, it is proposed that the distribution of allochthonous minerals now hosted by alluvial sediments reflects the pattern of glacial depositional processes within the mountains, in particular a directionally specific distance decay in the carryover of minerals from the limestone piedmont into Slieve Bloom.