Don’t Take all Geology Maps at Face Value

Intégrale were invited to visit the houses of a group of neighbours in the countryside near Calne, Wiltshire. The beautifully located study area, underlain by sandy Jurassic Calcareous Grit, sits at the crest of an escarpment with enviable views. The hillside downslope is mapped as (apparently undisturbed) Oxford Clay.

Unfortunately, the Oxford Clay displays the hummocky topography, with extensive boggy ground and reeds, of landslip (c. 10-12,000 years old); thus probably dating to the late Devensian Glaciation. It is surprising that such an extensive area of ancient landslip is not recorded on the geology map.

Recently reactivation of slippage along the old backscar, due to the high groundwater, has disrupted timber viewing  platforms. However, the ground movements are adequately remote from the houses to currently pose a risk of imminent structural distress.