The area around Dundee is mainly underlain by sandstones, siltstones and mudstones of Devonian age. To the north-west in the Sidlaw hills and to the south east along the southern shore of the Firth of Tay volcanic rocks of similar age outcrop. Small outcrops of intrusive igneous rocks occur under Dundee itself and between Dundee and the Sidlaw Hills. However, the bedrock geological formations are almost entirely covered by much younger (Quaternary) geological deposits. Glacial till predominates below Dundee and to the north while along the Firth of Tay and to the south alluvial deposits and peat are well represented.
Compressible material is associated with the alluvial deposits of the River Tay, which may contain layers of peat or interbedded clay, silt and sand, and with small, isolated deposits of peat elsewhere in the area.
Deposits containing sand which may become mobilised by flowing water (running sand) may be present in sandy alluvial deposits associated with the River Tay and other rivers and streams within the area. Potentially running sand deposits may also be present in deposits left by rivers and streams that were active when the ice melted at the end of the last glaciation (Fluvio glacial deposits). Since these deposits are not usually associated with current drainage networks they may not be saturated with water and are less likely to have the conditions for running sand to occur.
There are no significant outcrops of limestone, gypsum or halite in the area and problems due to soluble rocks are not likely to be present.
No areas with a significant potential for natural landslide activity have been identified, at the scale of the assessment. However, it is possible that small-scale instabilities may be present below the limits of resolution of the assessment, particularly where natural or artificial slopes meet strata with adverse dips of jointing or bedding.
No strata or deposits containing significant amounts of clay with a high potential for volume change have been identified in the area and problems due to shrink/swell clay subsidence are unlikely to occur.