The ice caps that covered large parts of the continents of the northern hemisphere during the Pleistocene glaciations drained huge quantities of meltwater. In several places the erosive power of the meltwater rivers has led to the formation of ice-marginal valleys (IMVs). A much-debated question is whether sediments deposited in IMVs by proglacial and extraglacial streams can be distinguished on the basis of their heavy-mineral content. This question was assessed by an inventory of the heavy-mineral assemblages from the middle part of the Toruń-Eberswalde IMV in northwest Poland, two sandurs that supplied sediment from the north and the pre-Wisła river system that supplied sediment from the south; all these streams fed the IMV. The largely similar heavy-mineral compositions and sediments concentrations of the middle part of the IMV and sandurs suggest that the sediment in the IMV was supplied almost entirely by the streams on the sandurs but also that some sediments were eroded from the Miocene subsoil of the IMV itself and for a small part from the south by the pre-Wisła river system. The only heavy mineral in the pre-Wisła sediments for which the percentage is significantly different from those in the sediments of the sandurs and the IMV terrace is epidote. The difference, however, is not seen in the sediments of the IMV so it can be concluded that the sediment supply to the middle part of this IMV by streams from the south was insignificant. This is in contrast with what was hitherto commonly assumed.

Bright white sands consisting almost exclusively of quartz (sometimes called ‘silver sands’) occur throughout the world; those in Europe commonly date from the late Paleogene and early Neogene. They have a clearly sedimentary origin, and they may have originated in various types of environments, but precise data are lacking because sedimentary research into these deposits (that have a high economic value) has been scarce. It is most likely that diagenetic processes are largely responsible for their exceptional appearance, but it is highly unlikely that all silver sands were subject to the same diagenetic conditions.

The precise origin of most of the silver sands is still enigmatic. In the case of the silver sands in the Dutch/German/Belgian border area, it appears that long-lasting in situ leaching by humic acids (resulting in an extremely low percentage of heavy minerals), in combination with differential cementation (and later partial dissolution of the cement), must be held responsible for the wide variety of the characteristics of these sands, including locally sharp boundaries with the underlying sands, lack of precipitates at the contact plane with the underlying sands, and the joint occurrence of strongly weathered and fresh specimens of the same heavy-mineral species.