Imperial College London

Dr Philippa J Mason

Faculty of EngineeringDepartment of Earth Science & Engineering

Senior Teaching Fellow



+44 (0)20 7594 6528p.j.mason Website




G31Royal School of MinesSouth Kensington Campus






BibTex format

author = {Toms, E and Mason, PJ and Ghail, RC},
doi = {10.1144/qjegh2015-086},
journal = {Quarterly Journal of Engineering Geology and Hydrogeology},
pages = {147--153},
title = {Drift-filled hollows in Battersea: investigation of the structure and geology along the route of the Northern Line Extension, London},
url = {},
volume = {49},
year = {2016}

RIS format (EndNote, RefMan)

AB - Drift filled hollows (DFHs) are a major subsurface hazard for engineering in London. They are characterised by a steeply inclined cone-shaped hollow into (sometimes through) the London Clay Formation, filled with unconsolidated fine to coarse-grained drift and often covered by terrace gravels, making them difficult to identify at the surface. Their origin remains uncertain but most likely formed towards the end of glacial epochs by meltwater scouring, perhaps of collapsed pingos. Usually associated with tributaries to the Thames, DFHs are particularly prevalent in the Battersea area, through which the Northern Line Extension (NLE) is to be built. This study uses 283 public borehole records and site reports to build a 3D geological ground model of two known DFHs in the Battersea area to develop a more complete understanding of their origin. We show that DFHs are likely older than previously assumed, dating from the end Anglian [MIS 12], ~300 ka ago, before the deposition of the River Terrace Deposits. The two DFHs modelled fall into distinct types: a small shallow DFH that is probably a purely scour feature in origin, and a larger, deeper DFH which probably formed by the scouring of a perhaps fault controlled pingo. It is unclear whether the faults controlled pingo formation passively by acting as a conduit for water, or in a more active sense by driving ground movements. Both DFHs represent a significant hazard for the NLE and require more detailed investigations to properly constrain their extent.
AU - Toms,E
AU - Mason,PJ
AU - Ghail,RC
DO - 10.1144/qjegh2015-086
EP - 153
PY - 2016///
SN - 1470-9236
SP - 147
TI - Drift-filled hollows in Battersea: investigation of the structure and geology along the route of the Northern Line Extension, London
T2 - Quarterly Journal of Engineering Geology and Hydrogeology
UR -
UR -
VL - 49
ER -