The clearest view of the contemporary alpine forests is found near Zürich in the lignitic deposits of Dürnten and of Utznach, which are so characteristic of the temperate period of the Third Interglacial Stage that Geikie has proposed to call this stage the _Dürntenian_.(8) It was, we recall, at Dürnten that Morlot(9) found the first proofs of a warm or temperate interglacial flora, between the deposits of a retreating glacier and those of an advancing glacier; for Dürnten is well within the region which was covered by the vast ice-fields both of the third and fourth glaciations. The forests which flourished there in Third Interglacial times were similar to those now found in the same region, consisting of the spruce, fir, mountain-pine, larch, beech, yew, and sycamore, with undergrowth of hazel. With this hardy flora are associated the remains of the straight-tusked elephant, of Merck's rhinoceros, of wild cattle, and of the stag; another evidence for our opinion that all these Asiatic mammals had become habituated to the cool temperate climate of the north. LIFE ON THE RIVER SOMME FROM PRE-CHELLEAN TO NEOLITHIC TIMES The borders of the River Somme at St. Acheul give us a vista of the whole story of the succession of geologic events; the great changes of climate, the procession of animal life, the sequence of human races and cultures. Here Commont(10) has found the key to the history of this entire country and enabled us to parallel events here with those occurring far away in Taubach, on the borders of the Thuringian forest, and at Krems in Lower Austria, as studied by Obermaier. This is because the 'older' and 'newer' loess periods, the succession of climates and of mammals, and the development of human cultures were all not local but _continental_ events. The purely local events are found in the kinds of gravels and soils which washed down over the terraces. It is very important first to clearly picture in our minds and understand the geography of the Somme at the time of the arrival of the Pre-Chellean flint workers. It appears certain that all three of the old river terraces composed of limestone had been cut long before and that the river had already reached the bottom level of the underlying chalk rock.(11) The higher terrace, then as now, was 100 feet above the Somme, the middle terrace about 70 feet, and the lowest terrace extended from a height of about 40 feet down underneath the present river level (see Fig. 59). [Illustration: FIG. 57. Three ancient river terraces (I, II, III), on the west bank of the Connecticut River in Vermont, believed to be of Postglacial age. The terraces are respectively 140, 60, and 20 feet above the river, and thus show a profile similar to that of the terraces on the Somme in Pre-Chellean times previous to the accumulation of the deposits bearing Palæolithic flints. Photograph by H. H. H. Langill.]