10 AlAKKS (iK I'KKCUSSION ON SILICKOUS KOCKS, 



first one. Tn ether words, that the parent block was turned 

 and the hainui'rr struck again the suifiice. The flake 

 thus detached cannot strictly be called an external flake, 

 though some portion of the original crust is still present 

 in it. We notice, however, that it is in a different posi- 

 tion ; instead of being present on the external face, it is now 

 on the proximal end of the flake. The external (Indical) 

 face of this flake i? really the counterpart (negative) of the 

 first flake that was detached from the same block. 



Flakes of this type may be called internal flakes, and 

 the nucleus of Kempton, with its 43 flakes, affords an ex- 

 cellent illustration of this type. The external (Indical) 

 face of the last flake that was sti'uck cff is formed by the 

 negatives of the internal faces of the two previous flakes, 

 their planes of fracture intersecting at an angle, and thus 

 producing a ridge extending more or less medially from 

 the proximal to the distal end. (Fig. 4h.) 



All flakes having one or more ridges extending from 

 the proximal to the distal edge, which are usually called 

 "knives^" are interna! flakes, because it is indubitable 

 that long and flat planes cannot be produced by subsequent 

 trimming or marginal chipping, but they must represent 

 the planes of fracture of previous flakes ; in other words, the 

 negatives of the Pollical (internal) face of such flakes (1). 



To the European mind the above seems to be the most 

 sensible method of striking off flakes. The mind of 

 archseolithic man, including the Aborigines, hit. however, 

 on still another one. 



Though I have not found, so far, a core and flakes illus- 

 trating this other method, the proofs are ample enough in 

 the shape of implements. Theoretically the external flake 

 should have sharp edges all round, because the plane of 

 fracture intersects the surface of the parent block in a line. 

 Specimens of this type are not very common, most of them 

 I found at Devonport. If. however, a larger number of 

 terc-watta is examined it will be not-icud that though they 

 are unquestionably external flakes, the proximal end, in- 

 stead of forming an edge, is truncated by a plane, which I 

 call "Percussion Face, P.F.,"' for reasons explained further 

 on, which always forms an obtuse angle with the Pollical 

 (internal) face. If the implement is, as is usually done, 



(1) Tlie f;iiii()iM .\uri(niae kniws appi'iir to me to l>e internal flake.«, anil their 

 peculiar form is, in my opinion, not the result of ;i tielilierate intention, but more 

 probai)ly <lue to the tiianner l>v whirh the Hakes were iletaeheil from »he parent 

 block. (See also the figure in Sir .lohn Kvans" hook illustrating the manufacture of 

 };un flints.) 



