'We are,' says Lenormant, 'in a position to affirm that the account of the Deluge is a universal tradition in all branches of the human family, with the sole exception of the black race, and a tradition every-*where so exact and so concordant cannot possibly be referred to an imaginary myth. No religious or cosmogonic myth possesses this character of universality. It must necessarily be the reminiscence of an actual and terrible event, which made so powerful an impression upon the imaginations of the first parents of our species that their descendants could never forget it. This cataclysm took place near the primitive cradle of mankind, and previous to the separation of the families from whom the principal races were to descend, for it would be altogether contrary to probability and to the laws of sound criticism to admit that local phenomena exactly similar in character could have been reproduced at so many different points on the globe as would enable one to explain these universal traditions, or that these traditions should always have assumed an identical form, combined with circumstances which need not necessarily have suggested themselves to the mind in such a connection.'[37] [37] _Les Origines de l'Histoire._ Brown's translation. On the geological side, the following may be accepted as a summary of facts:[38] [38] _Modern Science in Bible Lands_, 1888, pp. 244, 245, 251, 252. 'If the earliest men were those of the river gravels and caves, men of the mammoth age or of the palæolithic or palæocosmic period, we can form some definite ideas as to their possible antiquity. They colonised the continents immediately after the elevation of the land from the great subsidence which closed the pleistocene or glacial period, or in what has been called the "continental" period of the post-glacial age, because the new lands then raised out of the sea exceeded in extent those which we now have. We have some measures of the date of this great continental elevation. Many years ago, Sir Charles Lyell used the recession of the Falls of Niagara as a chronometer, estimating their cutting power as equal to one foot per annum. He calculated the beginning of the process, which dates from the post-glacial elevation, to be about thirty thousand years ago. More recent surveys have shown that the rate is three times as great as that estimated by Lyell, and also that a considerable part of the gorge was merely cleaned out by the river since the pleistocene age. In this way the age of the Niagara gorge becomes reduced to perhaps seven or eight thousand years. Other indications of similar bearing are found both in Europe and America, and lead to the belief that it is physically impossible that man could have colonised the northern hemisphere at an earlier date. These facts render necessary an entire revision of the calculations based on the growth of stalagmite in caves, and other uncertain data which have been held to indicate a greater lapse of time.