वेदों की प्राचीनता एवं काल-निर्णय / ओरायन (लोकमान्य बाल गंगाधर तिलक - खगोलीय वैदिक शोध)

THE GLACIAL PERIOD. 25 time is indubitably proved, yet scientific men have not been as yet able to trace satisfactorily the causes of this great catastrophe. Such immense mass of ice as covered the whole of Northern Europe and America during this period could not, like anything else, come out of nothing. There must be heat enough in certain parts of the globe to create by evaporation sufficient vapour, and aerial currents are required to transfer it to the colder regions of the globe, there to be precipitated in the form of ice. Any theory regarding the cause of the Ice Age which fails to take this fact into account is not only inadequate but worthless. A succession of Glacial periods, or, at any rate, the occurrence of two Glacial periods, must again be accounted for by the theory that may be proposed to explain these changes; and if we test the different theories advanced in this way, many of them will be at once found to be untenable. It was, for instance, once urged that the Gulf Stream, which, at present, imparts warmth to the countries in the North-West of Europe, might have been turned away from its course in the Pleistocene period by the submergence of the Isthmus of Panama, thus converting the countries on the North-Western coast of Europe into lands covered by ice. There is, however, no geological evidence to show that the Isthmus of Panama was submerged in the Pleistocene period, and we must, therefore, give up this hypothesis. Another theory started to account for the catastrophe was that the earth must have passed through cold and hot regions of space, thus giving rise to Glacial and Inter-Glacial periods respectively. But this too is unsupported by any evidence. A third suggestion advanced was that the supply of solar heat on earth must have varied in such a way as to give rise to warm and cold climates but this was shown to be a mere conjecture. A change in the position of the earth's axis might indeed cause such sudden changes in the climate; but a change in the 4