'Saskatchewan gravels and sands' is the name used for numerous, widely scattered deposits of gravel and sand found on the Canadian Prairies. These deposits represent the final phase of deposition by preglacial rivers before the first Pleistocene ice-sheet disrupted regional drainage. In the past, Saskatchewan gravels and sands have been identified chiefly by their absence of stones from the Canadian Shield and position below the drift in buried valleys or on low ground. These remain the basic criteria. Sole dependence on them, however, has resulted in extraneous deposits being called Saskatchewan. Such misidentifications cannot be eliminated entirely, but their number can be greatly decreased by use of additional checks. These include intensive study of each deposit and its topographic position, and establishing that there was both an adequate source for the gravel and sand contained in it and competent means of transporting that material from source to present site. In addition, the valley containing the deposit must have formed an integral part of the preglacial drainage system, its cross-section and longitudinal profile must have resembled those of a typical preglacial valley, and there must not have been any competing valley that could have carried the local, preglacial drainage more efficiently.