3. The prevalence among geologists of an exaggerated and unreasonable uniformitarianism, which refused to allow sufficient prominence to sudden cataclysms arising from the slow accumulation of natural forces, and which was a natural reaction from the convulsive geology of an earlier period, has caused the idea to be generally entertained that the age of palæocosmic men was of vast duration, and passed only by slow gradations and a gradual transition into the new conditions of the modern period. This view long was, and still is, an obstacle to any rational correlation of the geological and traditional history of man. Recently, however, new views have been forced on geologists, and have led many of the most sagacious observers and reasoners to see that the palanthropic period is much nearer to us than we had imagined. The arguments for this I have referred to in previous pages, and need not reiterate them, here. A few leading points may, however, be noted. One of these is the small amount of physical or organic change which has occurred since the close of the palanthropic period. Another is the more rapid rate of erosion and deposition by rivers in the modern period than had previously been supposed. Another is the striking fact that a large number of mammals, like the mammoth and woolly rhinoceros, seem to have perished simultaneously with the palæocosmic men, and this by some sudden catastrophe.[41] It has also been shown by Pictet and Dawkins that all the extant mammals of Europe already existed in the post-glacial age, but along with many others now altogether or locally extinct. Thus there seems to have been the removal over the whole northern hemisphere of a number of the largest mammals, while a selected number survived and no additions were made. Again, while at one time it was supposed that the remains of palæocosmic man and his contemporaries were confined to caverns and river alluvia, it is now known that they occur also on high plateaus and water-sheds, in beds of gravel and silt which must have been deposited there under conditions of submergence and somewhat active current drift, perhaps in some cases aided by floating ice.[42] Lastly, while, as must naturally be the case, in some places the remains of ancient and more modern men are mixed, or seem to pass into each other, in others, as in the Swiss, Belgian and Lebanon caves and in the superficial deposits, there is a distinct separation, implying an interval accompanied by physical change between the time of the earlier and later men. [41] Howorth, _The Mammoth and the Flood_. [42] Prestwich on deposits at Ightham, Kent, _Journal Geological Society_, May 1889.