Exposed river terrace formations in the Somme Valley that have been the subject of interest for geologists and archaeologists since the late 19th century. One of the first to study the sequence was V. Commont. He defined three main terraces according to their height above the floor of the buried channel below the terrace exposure: the High Terrace at 45 m, the Middle Terrace at 30 m, and the Low Terrace at 10 m. Although it is now known that Commont's sequence is oversimplified, nonetheless it is a reasonable approximation and allows a general understanding of several Lower Palaeolithic industries. The 45 m terrace is especially important because it is associated with a faunal assemblage of Cromerian affinities, broadly 200 000 to 300 000 years ago. It is here also that pear‐shaped bifacially worked handaxes that have come to characterize an Acheulian tradition now recognized throughout Africa and the Old World have been found in considerable quantity.
J. M. Coles and E. S. Higgs, 1969, The archaeology of early man. London: Faber & Faber