Field criteria for the recognition of till or tillite
Abstract Till is a highly variable sediment. It is formed and deposited by primary glacial and also by closely associated penecontemporaneous secondary non-glacial processes. Therefore, the range of the criteria useful for the recognition of till or tillite is very broad, and some of the characteristics are restricted to certain varieties of till only. Consequently no single descriptive characteristic would apply to all tills. Various site-specific petrographic characteristics of tills and also regional indicators of the presence of a glacier in the area investigated are discussed. By combining these multiple criteria, a sediment may be identified, or rejected, as till with a greater certainty than by applying only one or another set of the above criteria. Most of the characteristics of till or of the glacial environment can be identified in the field, and a regional study must supplement detailed site investigations.