THE ART OF PREHISTORIC MEN 37 



which they fabricated by means of deftly struck blows 

 all sorts of implements. Undoubtedly they also, by aid 

 of stone knives, saws and planes, made weapons and other 

 implements of wood and of the horns, bones, and teeth 

 of animals. But these latter substances are perishable, 

 and have only been preserved from decay under special 

 circumstances, such as their inclusion in the deposits on 

 the floors of caverns. 



The Stone Age is itself readily and obviously divisible 

 into two periods. The latter is a comparatively very short 

 and recent period, when great skill in chipping flints and 

 other stones was attained, and the implements so shaped 

 were often rubbed on large stones of very hard material 

 (siliceous grit), so as to polish their surfaces. This is 

 the " Neolithic," or later Stone, period, and extends back 

 in Europe certainly to 7000 B.C., and probably a few 

 thousand years further. Passing further back than this, 

 we leave what are called " recent " deposits, and come to 

 those associated with great changes of the earth's surface. 

 We enter upon '' geological " time, and vastly changed 

 climatic and geographical conditions. We are in the 

 older Stone period, called the " Palaeolithic period." 

 It is not really comparable to the " Neolithic," since it 

 comprises many successive ages of man, and, although 

 called the "Palaeolithic" or "ancient Stone" period, has 

 no unity, but, whilst readily divisible into several sub- 

 periods or epochs of comparatively late date, stretches 

 back into immense geologic antiquity indicated by flint 

 implements of special and diverse types, which are found 

 in definitely ascertained geologic horizons. 



The Pleistocene strata — the latest of the geologists' list 

 — are the river gravels of existing river valleys, the deposits 

 in many caves, and the sands and clays piled up by ice 

 action during the repeated glacial extensions or epochs 

 of glaciation which alternated with milder climate for 



