Glacial landsystems were first developed by Eyles (1983) and expanded more recently by Benn & Evans (1998) and then Evans and co-authors (2003) to include the wide range of process-form relationships associated with changing physiographic/tectonic settings and glacier ice characteristics. The landsystems approach provides us with a number of general guidelines for studying glaciated basins:
- The environmental significance of a sediment can be understood only with reference to its depositional position and the surrounding sediments and rocks
- Sediments are rarely deposited in isolation, but are laid down as part of an assemblage that reflects the process/es active in that environment
- Such assemblages can be recognised at a wide range of scales, from the very small to that of a whole continent or ocean basin
The environmental context of sediments can therefore be defined at different levels of a spatial hierarchy, beginning with the immediate locality and then in association with surrounding deposits expanding outwards to ever increasing horizons. At each successive level, the controls on the sedimentary system become larger in scale and longer-lasting in effect. This hierarchical approach to sedimentology, therefore, is a powerful means of describing how sediments, landforms and landscapes fit together, and determining how organisation in the landscape reflects the organisation of depositional processes and external controls in the environment. It forms the basis of facies modelling, or constructing descriptive and predictive models of relationships between different deposits. In areas where glacial deposits are lacking the landsystems approach integrates this information indicating that ice was erosive and exhausted the debris, or protective and never removed or modified the existing sediment.