4. Indeed not bones only, but objects of art, produced by human workmanship, are found fossilized and petrified by the like processes; and these, of course, belong to the historical period. Human bones, and human works, are found in such deposits as morasses, sand-banks, lava-streams, mounds of volcanic ashes; and many of them may be of unknown, and, compared with the duration of a few generations, of very great antiquity; but such deposits are distinguishable, generally without difficulty, from the strata in which the geologist reads the records of former creations. It has been truly said, that the geologist is an _Antiquary_; for, like the antiquary, he traces a past condition of things in the remains and effects of it which still subsist; but it has also been truly said, at the same time, that he is an antiquary _of a new Order_; for the remains which he studies are those which illustrate the history of the earth, not of man. The geologist's antiquity is not that of ornaments and arms, utensils and habiliments, walls and mounds; but of species and of genera, of seas and of mountains. It is true, that the geologist may have to study the works of man, in order to trace the effects of causes which produce the results which he investigates; as when he examines the pholad-pierced pillars of Pateoli, to prove the rise and the fall of the ground on which they stand; or notes the anchoring-rings in the wall of some Roman edifice, once a maritime fort, but now a ruin remote from the sea; or when he remarks the streets in the towns of Scania, which are now below the level of the Baltic,[1] and therefore show that the land has sunk since these pavements were laid. But in studying such objects, the geologist considers the hand of man as only one among many agencies. Man is to him only one of the natural causes of change.