The vast duration of this interglacial time is evidenced both in Europe and America by the deep cutting and wearing away of the 'drifts' brought down by the second glaciation. Penck believes that this 'long warm stage' represents a greater period of time than the entire interval between the third glaciation and the present time. The climate immediately following the retreat of the glaciers was cool and moist in the glaciated regions, but this was followed by such a prolonged period of heat and dryness that the glaciers on the Alps withdrew to a point far above their present limits. In one of the old 'high terraces' of the River Inn, in the north Tyrol, is a deposit containing the prevailing forest flora of the period, from which Penck concludes that the climate of Innsbruck was 2° C. higher than it is at the present time. Corresponding with this the snow-line stood 1,000 feet above its present level, and the Alps, save for the higher peaks, were almost completely denuded of ice and snow. A characteristic plant is the Pontic alpine rose (_Rhododendron ponticum_), which flourishes now in an annual temperature of 57°-65° Fahr.,(34) indicating that the climate of Innsbruck was as genial as that of the Italian slopes of the Alps to-day. This rhododendron is now found in the Caucasus. Other southern species of the time were a buckthorn, related to a species now living in the Canary Islands, and the box. There were also more hardy plants, including the fir (_Pinus sylvestris_), spruce, maple, willow, yew, elm, beech, and mountain-ash. The forests of the same period in Provence were, for the most part, similar to those now found in that region; out of thirty-seven species twenty-nine still occur in this part of southern France. On the whole, the aspect of southern France at this time was surprisingly modern. The forests included oaks, elms, poplars, willows, lindens, maples, sumachs, dogwood, and hawthorn. Among the climbing plants were the vine and the clematis. Here also were some forms which have since retreated to the south, such as species of the sweet bay and laurel which are now confined to the Canary Islands. The great humidity of the time is indicated by the presence of certain species of conifers which require considerable moisture. As in First Interglacial times, the presence of the fig indicates mild winters.