The Story of the Earth and Man
J. W. Dawson
language
(, May 23, 2013)
Physical geographers have taught us that the great continents, whether we regard their coasts or their mountain chains, are built up on lines which run north-east and south-west, and north-west and south-east; and it is also observed that these lines are great circles of the earth tangent to the polar circle. Further, we find, as a result of geological investigation, that these lines determined the deposition and the elevation of the oldest rocks known to us. Hence it is fair to infer that these were the original directions of the first lines of fracture and upheaval. Whether these lines were originally drawn by the influence of of the seasons on the cooling globe, or by the currents of its molten interior, or of the superficial ocean, they bespeak a most uniform and equable texture for the crust, and a definite law of fracture and upheaval; and they have modified all the subsequent action of the ocean as a depositor of sediment, and of the internal heat as a cause of alteration and movement of rocks. Against these earliest belts of land the ocean first chafed and foamed. Along their margins marine denudation first commenced, and the oceanic currents first deposited banks of sediment; and along these first lines have the volcanic orifices of all periods been most plentiful, and elevatory movements most powerfully felt.We must not suppose that the changes thus shortly sketched were rapid and convulsive. They must have required periods of enormous duration, all of which had elapsed before the beginning of geological time, properly so called. From Sir William Thomson’s calculations, it would appear that the time which has elapsed from the first formation of a solid crust on the earth to the modern period may have been from seventy to one hundred millions of years, and the whole time from the vaporous condition of the solar system to the present, must of course have been still greater than even this enormous series of ages. Such a lapse of time is truly almost inconceivable, but it is only a few days to Him with whom one day is as a thousand years, and a thousand years as one day. How many and strange pictures does this series of processes call up! First, the uniform vaporous nebula. Then the formation of a liquid nucleus, and a brilliant photosphere without. Then the congealing of a solid crust under dark atmospheric vapours, and the raining down of acid and watery showers. Then [15]the universal ocean, its waves rolling unobstructed around the globe, and its currents following without hindrance the leading of heat and of the earth’s rotation. Then the rupture of the crust and the emergence of the nuclei of continents.The Story of the Earth and Man, The Genesis Of The Earth, The Mesozoic Ages, Advent Of Man, Early Mammals and Birds, Primitive Man, Animals of the Sea