THE AGE OF STONE.
No doubt, as Lucretius said (see p. i6), the first anus or utensils of men were branches of trees or stones in the shapes in which they naturally offer themselves, without dressing of any sort. As has been previously shown in Volume I. (p. 22), the higher apes and monkeys are sufficiently intelligent to select, and even to preserve for muse, sticks and stones suited to their wants. The earliest efforts at making a tool were little more than breaking a convenient fragment from a rock or shaping one already nearly of the contour desired.
Marks of Rude Tools from Natural this close imitation of natural processes arises a constant difficulty in examining the oldest and the rudest specimens of human workmanship to decide whether they do or do not show undoubted signs of human handicraft. The cardinal questions of the antiquity of the race turn upon this point, and hence it has received a corresponding amount of attention from archzeologists. Specimens which to the untrained eye are merely broken stones convey to the erudite antiquary indubitable evidence of the formative skill of human intelligence. What these evidences arc must be known in order to appreciate the value of such researches as we are about to describe.
of first proof of the antiquity of a stone implement is that it has been found in a deposit in undisturbed connection with other objects whose age is beyond question. Of these the most con clusive are the bones of extinct animals, the shells of species no longer living at the locality, or fragments of plants whose species have long disappeared. A close study of the strata of the deposit may be decisive. Thus, many remains in the Belgian caves are covered with an undisturbed layer of fine mud which can be traced over a wide area, and which must have been deposited at some time when the whole country was overflowed with a wide expanse of still, muddy water. Others are underneath a floor of stalagmites, which could only have been formed by the gradual accre tions of thousands of years. Facts of this kind bear positive testimony
to a great antiquity.
or appearance of the implements also indicates a remote age. It is well known to mineralogists that the sur face of even the hardest stones undergoes a chemical change on exposure to the atmosphere. It may be very slight, and perceptible only by the microscope, but generally it is visible to the naked eye. The French call this patine, the English "weather-wearing." By studying it closely a practised eye will readily detect a modern from an ancient fracture of a stone, and will thus be exempt from the deceptions which are sometimes practised on scientific observers.
Varieties of variety of stone often serves as a guide. The natural dispersion of rocks can often be clearly defined, and what lies beyond this must be attributed to other agencies. Thus, if a piece of obsidian were found in undisturbed alluvium on the Atlantic seaboard of the United States, it would testify to the presence of man as clearly as a perfect implement. The green mineral jade or nephrite has thus served to trace the migrations and commerce of extinct tribes. Flint chips from a particular variety of stone obtainable only from a locality known as Flint Ridge, Ohio, have been found on the banks of the Mississippi; their presence there testifies unmistakably to human conveyance (see p. 82).
Evidences of Alan's to leading evidence of man's handiwork is a prevailing unity of shape adapted to a purpose. If we exhume from an ancient undisturbed deposit a number of stones roughly broken into similar shape and size, and adapted to holding in the hand or to adjusting to a helve, we have in this strong cumulative evidence that they are products of human ingenuity. Blind natural forces do not work in this way, and, no matter how little else there may be to indicate their origin, we are not likely to err in assigning such specimens to some ancient tribe.