Molluscs are among the most ubiquitous fossils found in Quaternary non-marine sediments. They are found in a wide variety of deposits including: loess, cave, sinkhole and fissure deposits; fluvial, lacustrine, glaciolacustrine and paludal sediments; and spring-fed travertine accumulations.
In spite of problems associated with identification of some species from shell morphology alone and a general inadequacy in our understanding of the factors controlling modern species distribution, Quaternary studies of non-marine molluscs have resulted in some significant contributions. In North America fossil molluscs have been used to: (1) reconstruct former stream confluences; (2) provide a basis for biostratigraphic zonation of sedimentary sequences in the Lake Michigan, Superior and Huron basins; and (3) reconstruct local habitat and climatic conditions. Isotopic data obtained from the analysis of molluscan shell has provided information about the environment in which the molluscs lived. Amino acid studies of the shell protein have provided information about the age of fossil assemblages and a method for estimating post depositional effective temperature histories of fossil sites.
One of the basic problems in Quaternary biogeography concerns the timing, the nature, and the magnitude of biotic changes that accompanied glacial advances and retreats. The ubiquity of non-marine molluscs in Quaternary sediments provides an excellent opportunity to study effects of both short and long scale climatic fluctuations on at least one important part of the non-marine biota, the molluscs.