Geology

Treats of the structure of the earth and its physical record from the earliest times. One of the youngest of the Natural Sciences; scarcely existent before 1800. As Chemistry sprung from Alchemy, or the vain search for the Philosopher's Stone and the Elixir of Life, so Geology had its beginning in the crude speculations of early thinkers on the origin of things. Its progre was sadly impeded by cosmogonic doctrines, which Ideal landscape of the Cretaceous Period. had become ingrained into the theological systems of the ancients, and the superstitions of the Middle Ages. Its early history is almost a continuous narrative of attempts to harmonize the facts of Nature with the doctrines of the various sacred books, or of persecution directed against those who dared to di ent from the current dogmas of the age. The alternate advance and rece ion of thought on geological subjects is well shown by a study of a few of the leading original works on the science that have been preserved. The views of the ancient Egyptians and Indian philosophers were merely speculative. Among the Greeks the sensible teachings of Pythagoras in the 6th century B.C. are preserved in Ovid's Metamorphose (book xv.), and evidence a closene of observation that would do credit to a geologist of this day. Among other aphorisms of his we find the following: "Sea has changed into land. Marine shells lie far distant from the deep."-"Valleys have been excavated by running water, and floods have washed down hills into the sea."-" Volcanic vents shift their position. There was a time when Ætna was not a burning mountain, and the time will come when it will cease to burn." Aristotle has left in his Meteorics similar profound remarks; e.g. , "The changes on the earth are so slow in comparison with the duration of our lives that they are overlooked, and the migrations of people cause them to be forgotten.""The distribution of land and sea does not endure for all time." -" As time never fails, and the universe is eternal, neither the Tanais nor the Nile can have flowed forever." Strabo, in the first century A.D., writes: "The waters have not risen nor subsided, but the level of the land has been changed, and this has brought some of it below water."-" It is proper to derive our explanations from things which are obvious and of daily occurrence." Such views were far in advance of what we might expect from so distant a date, and indeed of those which were held in centuries long afterward. A millennium pa ed away before the lost or broken clew was taken up again. In the palmy days of the Moslem empire, sometimes in the guise of fable and sometimes in plain language, the writers recorded their observations and deductions. But the literary age in Bagdad pa ed away, and for five or six hundred years the sleep of intellectual torpor or death remained unbroken. Then Italy led the way, and the great conflict began of scientific truth against speculative error. "They tell us," wrote Leonardo da Vinci, the painter, "that fo il shells were formed in the hills by the influence of the stars: but where, I ask, are shells now forming under the influence of the stars? and how can the stars explain the origin of gravel composed of pebbles rounded as if by running water?" Falloppio of Padua, the anatomist, wrote: "Petrified shells were generated by fermentation in the spots where they are found from the tumultuous movements of terrestrial exhalations. The tusks of certain fo il elephants dug up in Italy are mere were natural impre ions that had been somehow stamped on the soil." It is not easy now to believe that men of sense and eminence in the learned profe ions could utter notions so fantastical; but in reality a hundred years were spent in combating and overthrowing this absurd delusion, which apparently arose from an unwillingne , on theological grounds, to admit the existence of any other races of animals than those now living.