Rivers receive much coarse detritus from the landscapes they drain and much of this remains are incorporated in their valleys in various bodies of sediment. The fact that a large proportion of the Pleistocene archaeological record comes from fluvial deposits is therefore unsurprising. In rare cases the knapping locations on river beds and beaches have been preserved as primary-context, but more important components of the record where more randomly embedded in to the river terraces. The coincidence between the fluvial and archaeological record may result from other factors, such as the attractiveness of river valley locations for early human habitation and the opportunities for artifact discovery that resulted from gravel extraction, especially before mechanization during the 19th and early 20th century.
The most valuable fluvial archives are those in which dating evidence also occurs, providing a chronological framework for the archaeological record. Example sequences, in which this principle has been well established, include those of the Thames and the Somme and the Seine.
The Seine and the Somme are the two main rivers flowing from northwestern France into the Channel. During the Pleistocene cold stages both rivers were tributaries of the River Manche which was exporting sediments into the central deeps of the Channel. The River Seine has a very well developed terrace system recording incision that began at around 1 Ma. The same age is proposed for the beginning of the main incision in the Somme Valley on the basis of morphostratigraphy, pedostratigraphy, palaeontology, palaeomagnetism and ESR dating.
Handaxes began to be a common component of the Paleolithic Ensembles at about 600 k.a. BP. The percentage of bifaces tends to diminish after OIS 8, whereas a significant presence of the Levallois technique is observed in North West Europe from OIS 7 onwards. The artifacts that replaced handaxes show a trend for diversification, both in their chaine operatoire and typology. Mousterian ensembles are already present at Maastricht-Belvedere at 270-222 k.a. BP and Biache St. Vaast at 175 k.a. BP.