The Quaternary deposits summary lithologies dataset is a digital geological map across the bulk of the UK Continental Shelf (UKCS), for areas up to a water depth of 200 m, which groups the deposits into classes based on similar engineering geology characteristics. The map is derived from (unpublished) BGS 1:1,000,000 scale Quaternary digital geological mapping, so is effective at that scale. The map was produced in 2014 in collaboration with, and co-funded by, The Crown Estate as part of a wider commissioned project to assess seabed geological constraints on engineering infrastructure across the UKCS. The divisions on the map combine the Quaternary deposits into 7 categories of similar strength and lithological variability, each with a ‘Category’ title that summarises their main lithological character: diamict; firm to hard interbedded (layered); firm to hard mud; sand and gravel; soft interbedded; soft mud; undifferentiated. These categories can be used as a basis for assessing, in conjunction with a range of other geological factors, the geological constraints on engineering structures at or close to the seabed. The data are held by the BGS as an ESRI ArcGIS Shapefile.