TOOLS MAKYTH MAN—OAKLEY 433 
merly in part Upper Pliocene) distinguished by the spread of ele- 
phants of the genus Hlephas, oxen (Bos), and one-toed horses 
(Equus). Owing to these changes in nomenclature, deposits which 
were formerly “Early” Pleistocene are now counted as Middle Pleisto- 
cene (e.g., the Abbeville gravels and the Trinil beds) ; while other 
deposits fermienly ecemade as Pliocene, i.e., Tertiary, for example the 
Red Crag of East Anglia, are now regarded as Lower Pleistocene by 
the majority of geologists. The “glacial Pleistocene” is estimated to 
have been about half a million years in duration, but the addition of 
the Villafranchian stage has nearly doubled the length of the period. 
The problem of eoliths, supposed artifacts of Tertiary man, was first 
raised by the discoveries of Abbé Louis Bourgeois, who found in 1867 
a great quantity of chipped flints, in the forms of alleged scrapers, 
knives, and borers, in a fresh-water deposit of Lower Miocene ® age 
near Thenay (Loir-et-Cher). From time to time similar chipped 
flints were reported in other Tertiary formations: in Lower Eocene 
strata at Clermont (Oise), in Upper Oligocene gravels at Boncelles, 
Belgium, in “Upper Miocene” (now Lower Pliocene) deposits at Puy 
Courny, Cantal, in the so-called Pliocene plateau gravels on the North 
Downs in Kent, and within and below the Red Crag of East Anglia. 
With the growth of knowledge on the evolution of the primates, 
based on a study of actual fossil remains, it has become clear in the 
present century that our forerunners had only the size range of bush 
babies throughout Eocene times. Man-sized apes did not emerge before 
the Miocene period, while the earliest manlike remains date from early 
Pleistocene times. Thus, pre-Miocene eoliths at any rate may now be 
dismissed as geological curiosities, with no bearing on the origins of 
tool making. The unreliability of the criteria used by the earlier 
archeologists who recognized “flints shaped by human agency” in the 
Tertiary formations is evident from the fact that Eocene eoliths are as 
convincingly artificial in appearance as many of those from lai 
formations! ae 
In some circumstances flint is very readily fractured, and the eal 
agencies which cause it to be chipped into shapes reminiscent of artifice 
are legion. The eoliths found in Tertiary river gravels are strikingly 
similar to flints broken by violent agitation in the water of chalk mills. 
This is understandable. An accumulation of flints of eolithic form was 
found in a river gravel in a valley in Wiirtemberg where the material 
carried by the main stream had evidently been drawn into whirlpools 
caused by the inflow of tributaries. Another agency which results in 
the production of pseudoartifacts is the pressure combined with move- 
ment occurring when flint-bearing strata founder through the solution 
of underlying chalk or other calcareous formation. This was the 
agency chiefly responsible for the Clermont eoliths. The Kent eoliths 
* Aquitanian : classified by some authors as Upper Oligocene. 
