York Archaeological Trust
The solid geology of the area is Bunter Sandstone (British Geological Survey (England and Wales) Sheet No. 63 1967), laid down in the Triassic period, 225 million years ago (Warrington 1974). This is overlain by glacial till or boulder clay, warp and lacustrine clays, formed by peri and post-glacial activity, and alluvial deposits from the River Foss. The latter form a thick band of naturally derived river silts. The part of the development area examined in this series of probe-holes slopes gently down from west to east from approximately 10.70m Above Ordnance Datum (AOD) to roughly 9.80m AOD.