INTRODUCTORY CHAPTER. 615 



organisations, flourishing upon the earth before the present races appeared, the monuments 

 of His skill ; and while He is to be praised, for enabling man, with limited capacities, and 

 inhabiting a spot so comparatively small, to acquaint himself with forms that have been 

 blotted from the book of life, it is man's obvious duty, and as much to his advantage, to 

 contemplate these works of His hands, and demonstrations of His attributes. 



The acquirement of correct views respecting the condition of the crust of the earth, 

 and the fluctuations it has undergone, is of very recent date; though several of the ancient 

 Greek and Roman writers possessed no inconsiderable amount of geological knowledge. 

 Strabo discussed the question of the occurrence of marine shells at a distance from the 

 shore, and at great elevations, and offered the theory of an upheaving cause in explanation, 

 substantially the same as that adopted in modern times. The following passage from the 

 philosophical geographer, written more than two thousand years ago, expresses the iden 

 tical proposition which forms the basis of Sir C. I/yell's introductory volume on the Princi 

 ples of Geology : " It is proper," he observed, " to derive our explanations from things 

 which are obvious, and in some measure of daily occurrence, such as deluges, earthquakes, 

 volcanic eruptions, and sudden swellings of the land beneath the sea; for the last raise up 

 the sea also ; and when the same lands subside again, they occasion the sea to be let down. 

 It is not merely the small, but the large islands, and not merely the islands, but the 

 continents, which can be lifted up, together with the sea ; and both large and small tracts 

 may subside, for habitations, and cities, like Bure, Bizona, and many others, have 

 been engulfed by earthquakes." In Lucretius, we have a description of monstrous 

 quadrupeds, recognised as existing previous to man and the present race of animals, 

 which might almost warrant the belief that some fossil gigantic skeleton had met his 

 eye: 



" Hence, doubtless, earth prodigious forma at first 

 Gender'd, of face and members most grotesque ; 

 Monsters, half-man, half- woman 



shapes unsound, 



Footless, and handless, void of mouth or eye, 

 Or, from misjunction, maim'd of limb with limb. 



Many a tribe has sunk supprest, 

 Powerless its kind to gender." 



In the fifteenth book of the " Metamorphoses " of Ovid, the poet, when detailing the 

 Pythagorean doctrines, adduces a series of examples of that process of change, attributed 

 by the philosopher of Samos to nature, which sufficiently separate him from the class 

 of speculatists, and entitle him to rank with physical inquirers. The chief instances of 

 variation enumerated are 



The conversion of the sea into dry land, and the dry land into sea. 



The occurrence of marine shells at a distance from the shores, and of anchors fixed on 

 the summits of the hills. 



The reduction of hills to plains, and the scooping out of valleys in the plains by the 

 action of floods, with the transportation of their detritus to the sea. 



The change of bogs into solid ground, and the formation of stagnant pools in dry 

 places. 



The opening of springs, and the damming up of rivers, as the effect of earthquakes, 

 compelling them to pursue a new course ; of which last phenomenon, the Erasimus in 

 Greece, the Lycus and Mysus in Asia Minor, are the given instances. 



The conversion of the waters of certain rivers from sweet to brackish, as those of 

 Anigris and Hypanis. 



The increase of continents, by the junction of islands, through the growth of deltas and 



