ABSTRACT
This chapter discusses the occurrence, the origin and the dispersal of glacial boulders with emphasis on their usefulness to understand the genesis of till, to trace back ore boulders to their sources, and to decipher complexly changing ice-sheet configurations. Boulder tracing involves the recognition and reconstruction of dispersal fans or trains leading up-glacier to the source area, as simply as the smoke plume leads back to the chimney. The glacial transport of debris, eventually to be deposited as till, is a complex system which involves the conditions of flow of the ice and the conditions of debris acquisition and deposition by the glacier. Boulders represent a sample only of the whole of the transported glacial debris by a given mass unit of glacier ice. The most important single factor affecting the transport distance of boulders is lithologic in nature, namely the resistance of different lithologies to abrasion and crushing during glacial transport.
