Chapter 4 Conceptual glacial ground models: British and Irish case studies

Abstract

Abstract Former glaciation style is dictated by physiography and ice dynamics and is encoded in glacial landsystem imprints. As a holistic evaluation of sediment–landform associations and their genetic relationships to the processes involved in terrain development, glacial landsystems can facilitate a preliminary prediction of expected subsurface conditions using depositional surface morphology and wider physiographic setting. This chapter provides exemplars representative of the widely variable glacial depositional environments of the British Isles. The glacial deposits of the British Isles are viewed in terms of the dominant landsystems in the Quaternary sediment–landform record and can be grouped under four categories: (1) ice-sheet-related deposits and (2) upland (hard bedrock) glacial deposits, organized according to subglacial footprints, ice-marginal complexes and supraglacial assemblages; (3) glaciofluvial sediment–landforms, organized according to whether they are ice-contact or proglacial in nature; and (4) subaqueous depositional sequences, related to ice-proximal and ice-distal environments. These glacial landsystems are related to the concept of Quaternary domains in an attempt to translate sediment–landform assemblages into a format that has practicability in engineering geology. In this respect the regional distribution of landsystems resonates to some degree with the classification schemes of ‘glaciogenic subgroups’ and ‘till formation domains’. Beyond the glaciogenic subgroup and domain classifications, landsystems further identify localized complexities and ensure a higher level of detail for site investigations where intensive Quaternary geological assessments have yielded a range of data including geomorphological mapping and outcrop investigations with three-dimensional analyses of borehole archives.