Refining the known extent of major onshore Quaternary glaciation in the UK — types of evidence, nomenclature and uncertainty

Repeated cycles of Quaternary glaciation have had a major impact on the morphology and shallow sub-surface properties of much of the UK landscape and continental shelf. Understanding the extent of glaciation involves understanding of our landscape history but is also critical to the broad range of applied users that interact with the shallow sub-surface including engineers, hydrogeologists, planners and decision makers. Numerous interpretations of the onshore extent of the Anglian and Late Devensian glaciations have been published. However, many are not clearly evidenced or justified, being sometimes based on anecdotal evidence or supposition, with the levels of associated uncertainty not effectively communicated. As part of this work, the long-term record of Quaternary glaciation within the UK is reviewed and the types of geological and geomorphological information that can be employed to interpret their former extent are assessed. We also examine the range of factors that may influence the relative preservation of this evidence. As part of this assessment, we recommend abandoning the term ‘glacial limit’ (and other related synonyms) when interpreting the extent of glaciation within the geological record. Instead, we recommend using the term limit of preserved evidence which more accurately reflects the spatial context of such evidence. Finally, we present new onshore linework for the limit of preserved evidence of both the Anglian and Late Devensian glaciations, presenting how this linework was captured and the associated levels of uncertainty.