For one site, Pyllau Cochion near Horeb, Swansea University studied preserved pollen and plant remains taken from a 6-m deep peat core, from a bog that started forming after the last Ice Age.
Ar safle Pyllau Cochion ar bwys Horeb astudiodd Prifysgol Abertawe weddillion paill a phlanhigion a gymerwyd o graidd mawn 6m o ddyfnder, mewn cors a ddechreuodd ffurfio ar ôl yr oes iâ ddiwethaf.