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The Meeting-Place of Geology and History. Sir John William Dawson
Читать онлайн.Название The Meeting-Place of Geology and History
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isbn 4064066157449
Автор произведения Sir John William Dawson
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CHIPPED QUARTZITES, MODERN AMERICAN (after Holmes)
Upper line (1 to 6), unfinished and rejected pieces.
Lower line (7 to 18), progress of development from the unfinished oval form to finished lance and arrow-heads.
For the present, therefore, we may afford to pass over with this slight notice the alleged occurrence of miocene and pliocene man, and this the rather since, if such men ever existed in the northern hemisphere, the cold and submergence of the pleistocene must have cut them off from their more modern successors in such a way that man must practically have made a new beginning at the close of the glacial age.
I do not refer here to the finds of skulls and implements in the auriferous gravels of Western America. Some of these, if genuine, might go back to the pliocene age, but in so far as the evidence now available indicates, they all belong to the modern races of Indians, and, in one way or another, by fraud or error, have had assigned to them a fabulous antiquity.
There still seems reason to believe that remains of man and his works exist in beds which are overlaid by boulders and gravel, implying a cold climate. These may indicate the last portion of the glacial period proper, in which case the beds with human remains may be called inter-glacial, or they may indicate a partial relapse to the cold conditions occurring after the glacial age had passed away, and in the early part of the modern period. My own view is, that it is most natural to draw the boundary line of the pleistocene and anthropic or modern at the point where the earliest certain evidences of man appear, and that the anthropic age will be found to include not only an early period of mild climate succeeding the glacial age, but a little later a return of cold, not comparable with that of the extreme glacial period, but sufficient seriously to affect human interests, and which almost immediately preceded those physical changes which carried away palæocosmic man, or the man of the earliest period, and many of his companion animals, and introduced the neanthropic or later human age. We shall find facts bearing on this in the sequel.
In the meantime, we may consider it as established beyond cavil that man was already in Europe immediately after the close of the glacial period, and was contemporary with the species of animals, many of them large and formidable, which at that time occupied the land. He must have entered on the possession of a world more ample and richer in resources than that which remains to us. The early post-glacial age was, like the preceding pliocene, a time of continental elevation, in which the dry land spread itself widely over the now submerged margins of the sea basins. In Europe, the British Islands were connected with the mainland, and Ireland was united to England. The Rhine flowed northward to the Orkneys, through a wide plain probably wooded and swarming with great quadrupeds, now extinct or strange to Europe. The Thames and the Humber were tributaries of the Rhine. The land of France and Spain extended out to the hundred-fathom line. The shallower parts of the Mediterranean were dry land, and that sea was divided into two parts by land connecting Italy with Africa. Possibly portions of the shallower areas of the Atlantic were so elevated as to connect Europe and America more closely than at present.
Connected with this elevation of the continents out of the sea was a great change of climate, whereby the cold of the pleistocene age passed away and a milder climate overspread the northern hemisphere, while the newly-raised land and that vacated by snow and ice became clothed with vegetation, and were occupied by a rich quadrupedal fauna, including even in the northern parts of Europe, Asia, and America, species of elephant, rhinoceros, and other genera now confined to the warmer climates. This new and noble world was the rich heritage of primeval man.
Pictet has estimated the number of species of mammals inhabiting Europe in the palanthropic period at ninety-eight, [12] of which only fifty-seven now live there, the remainder being either wholly or locally extinct—that is, they are either not now existing in any part of the world, or are found only beyond the limits of Central, Western, and Southern Europe. The extinct species also include the largest and noblest of all. It has been remarked that the assemblage of palanthropic species in Europe and Western Asia is so great and varied that with our present experience we can scarcely imagine them to have existed contemporaneously in the same region. For example, the association of species of elephant and rhinoceros, the musk-sheep, the reindeer, the Cape hyena, and the hippopotamus seems to be incongruous.
[12] Zittel, in a recent paper (1893), gives 110 species of mammals in the pleistocene and early modern. Of these about twenty of the largest and most important are extinct.
Various theories have been proposed to remove the difficulty. Modern analogies will allow us to believe in such astounding facts if we take into account the probability of a warm climate, especially in summer, along with a wooded state of the country providing much shelter, and wide continental plains affording facilities for seasonal migrations. There were no doubt also climatal changes in the course of the age, which may have tended to the remarkable mixture of animal types in its deposits. In connection with this there is now every reason to believe that while, in its earlier part, the palanthropic age was distinguished by a warm climate, in its later portion a colder and more inclement atmosphere crept over the northern hemisphere. As an illustration of this, it is known that in the earlier part of the period a noble species of elephant named Elephas antiquus, and a rhinoceros (R. Merkii), abounded in Europe; but as the age advanced these species disappeared, and were replaced by the mammoth (E. primigenius) and the woolly rhinoceros (R. tichorhinus), animals clothed like the musk-ox in dense wool and hair, and evidently intended for a rigorous climate. With and succeeding these last species, the reindeer becomes characteristic and abundant. It is, as we shall see, a point of much importance in what may be called the prehistoric history of man, that he was introduced in a period of genial temperature as well as of wide continental extension, and survived to find his physical environment gradually becoming less favourable, and the age ending in that great cataclysm which swept so many species of animals and tribes of men out of existence, and reduced the dry land of our continents to its present comparatively limited area.
I should, perhaps, have noticed here the worked flints found so abundantly in some parts of the south of England, which have long attracted the attention of collectors, and have in some cases been referred to glacial or pre-glacial times. I believe, however, they are all really post-glacial, though in some cases belonging to the earliest portion of that period. [13]
[13] Prestwich on 'Ightham Beds,' Journ. Geol. Soc., 1893; Dawkins, Journ. Anthrop. Soc., 1894.
We may close the present chapter by presenting to the eye in a tabular form the series of events included in the pleistocene and modern periods of the great cenozoic time.
LATER CENOZOIC, OR TERTIARY PERIOD
(In Ascending Order, or from the Older to the Newer)
Newer Pliocene.—A continental period of long duration, elevated land, much erosion, much volcanic action.
Pleistocene.—Irregular elevation and depression of the land, ending in wide submergence with cold climate. Glaciers on all mountains near to coasts and ice-drift