Shallow geophysical surveys undertaken within the Blane Valley, floore
d by Loch Lomond Stadial proglacial lake deposits, show that the Pleis
tocene sequence is significantly thicker than previously suspected. Se
ismic refraction, resistivity and gravity data demonstrate that the de
pth to the Upper Old Red Sandstone bedrock varies from 30-100 m, sugge
sting significant relief on the submerged bedrock surface. The Pleisto
cene sequence extends to about 80 m below Ordnance Datumn.