Tills are a distinctive geological and engineering group of soils which are characterized by a wide range of behavioural patterns and a high degree of variability. As a means of identifying the various geological types of tills, a classification system based on their modes of formation, transportation and deposition has been developed. To accommodate the inherent variability of tills, sub-division of these classifications has been carried out on the basis of their gradational characteristics. Further, the fabric features contributing to variability in engineering behaviour are identified. From this, extended classifications are tentatively suggested to aid the prediction of the engineering properties of tills and the selection of the most appropriate sampling and testing techniques for them.