It follows that he who would investigate fairly the claims of Geology, must first learn to appreciate the significance of these facts, and to estimate the value of these arguments. And this is precisely what we have been trying to do. We are not writing a treatise on Geology. Certainly not: it would be presumptuous in us, with our scanty knowledge, to attempt it. Besides, Geology has it own professors, and its lecture-halls, and its manuals. Neither do we mean to assume the character of the advocates or champions of Geology. It does not ask our services; in its cause are enrolled no small proportion of the most illustrious names which for the last fifty years have adorned the annals of Physical Science. Nor do we want even to enforce upon our readers that more general theory of Geology which we are endeavoring to explain and illustrate. Our purpose is merely to collect from various sources, and to string together, the evidence that may be adduced in its favor; that so, when we come hereafter to consider this theory in its relation with the History of the Bible, we may not incur the risk of discomfiture by denying that which has been proved by facts, but rather approach the subject with such knowledge as may help us to discover the real harmony that we know to exist between the truths inscribed on the works of God, and those which are recorded in His Written Word. In the accomplishment of this task we have devoted ourselves chiefly to the study of the Aqueous or Stratified Rocks. According to Geologists, these rocks, such as we find them now, were not the immediate work of creation, but were slowly produced in the long lapse of ages, and laid out one above another, by a vast and complex machinery of secondary causes. The elements of which they are composed were gathered together from many and various sources; from the ocean, from the air, from other pre-existing rocks; and, for aught we know, may have had a long and eventful history before they came to assume their present structure and arrangement. Thus, for example, the Conglomerates, and Sandstones, with which we are so familiar, are made up of broken fragments derived from earlier rocks, and then transported to distant sites by the mountain torrents, or the stately rivers of vast continents, or the silent currents of the sea; the Limestone with which we build our houses is the work of living animals that once swarmed in countless myriads beneath the waters of the ocean; and the Coal which supplies the motive power to our manufactories, our railways, our ships of war and commerce, is but the modern representative of ancient swamps and forests, which, having been buried in the earth, and there, by the action of chemical laws, endowed with new properties, were laid by for the future use of man in the great storehouse of Nature.