STONE IMPLEMENTS PROM SHORES OF LAKE MICHIGAN. 591 



occupies nearly the whole of one surface of the stone, while two or three 

 facets may occur within this space. Commonly where a flake has been 

 detached, wliether of large or small size, further flaking has not been 

 carried on in the same quarter, but has been repeated at intervals of 

 about a fourth or a third or even half the distance around the stone. 



Two and three faceted stones are about equally represented and com- 

 prise the greater part of the flaked cobblestones. (Plate I.) Those with 

 one facet are in fair projDortion, while four and five faceted stones are 

 less numerous. A limited number have more than five facets. The 

 order of the letters a, h, <?, d is the supposed order of flaking. 



Halves of flaked cobblestones, mainly the result of fractures running 

 through the shorter diameter, occur in the proportion of one to every 

 four or five of the unbroken specimens; in extent of flaking, as in other 

 characters, they usually corresx)ond with the stones just described. 

 Other broken products, in a variety of forms, represented in the refuse 

 by split or shattered portions of the faceted stones, by large inner flakes 

 and by fractured outer flakes, suggest that some cobblestones have 

 been wholly reduced to flakes and splinters. (Plate I, fig. 8.) These 

 products are limited in number, and are not easily separated from the 

 flakes proper. An idea of their relative frequency is gained only from 

 the occurrence of similar results in experimental flaking when attempts 

 are made to secure from a single stone all possible outer flakes. 



The flakes. — On the various sites studied the flakes are much more 

 numerous than the other trap products, and the excess of outer flakes is 

 particularly noticeable. In most cases the smooth convex surface of the 

 original stone forms one entire side of the flake, while a less convex and 

 rougher surface, showing the characteristic fracture of the rock, forms 

 the ojjposite side. The two surfaces meet in a continuous edge extend- 

 ing around the flake. The thicker end or margin is marked by a 

 percussion notch in the edge, like that found in the nucleus facet, or 

 flake bed, and by similar furrows radiating from it for a short distance 

 over the face of the fracture. 



Beyond the radiating furrows, and nearer the opposite margin, the 

 greatest convexity of the face of fracture occurs and extends across the 

 flake in a curve having its center in the notch. The degree of convex- 

 ity of this face depends upon the length of the flake; the greater the 

 length the nearer the apx^roach to a plane surface ; a concave flake is 

 rarely met with. The waterworn face has its greatest convexity near 

 the margin that received the blow, to which it descends more abruptly 

 for about one-third of the circumference; the remaining two- thirds 

 present an edge like that of a knife, the surfaces meeting acutely. The 

 edge does not lie wholly in one plane, but approaches nearly that posi- 

 tion; although apparently sharp, it is uneven to the touch, The main 

 characteristics of the flakes are easily made out in the photographs and 

 drawings presented. 



Of the irregular flakes the greater number are also from the outside 



