40 BUREAU OF AMERICAN ETHNOLOGY [Bull. 177 
ever, as more of the specimens were handled it became clear that spe- 
cific tool types were represented. A discussion of the problem with 
geologists indicated that the type of fracture involved could not have 
been produced by any natural agency, but must have been the result 
of intentionally struck blows. In some cases, as with the objects 
classed as choppers or chopper-hammerstones, the fracture appears to 
be the result of use. In other tools, such as picks, there seems to 
have been some attempt at shaping. Thus, even though some of the 
types appear to be only roughly shaped, the fact that they occur con- 
sistently from site to site and could not have been accidentally formed 
by nature indicates they represent characteristic tool types of the 
Alaka Phase. The type descriptions of the stone artifacts are 
grouped according to method of manufacture. The first two cate- 
gories include tools shaped solely by percussion without any further 
modification, using either the core or the percussion struck flakes; 
the third category is percussion-struck tools with some modification 
by abrasion, especially the bit of celts; the fourth category contains 
well polished tools shaped by pecking and grinding. 
The artifact types, their rock material, and their exact provenience 
are shown in detail in the Appendix, table 1. 
PERCUSSION-MADE CORE TOOLS 
Choppers (fig. 8; pl. 10)—Large waterworn cobblestones usually 
of andesite, range from 6-15 cm. long, 6-10 cm. wide, and 3-6 cm. 
thick. A few large flakes have been struck off the sides and working 
edge, either deliberately or from hard use. Sometimes a core frag- 
ment has been used as a chopper and the edge shows battering (fig. 8, 
d). The characteristic feature of these objects is a chopping edge, 
which in cross section tapers from a thickness of 2-3 cm. to a blunt 
edge 2 to 5 mm. wide. These tools show use fracture in the form 
of long fracture planes at right angles to the cutting edge. 
Chopper-hammerstones.—Some of the choppers have one edge that 
is so blunt and rounded that it could not have been used in any way 
other than to strike a blow or for pounding. The size and irregular 
shape are within the range of the previously described choppers. 
Hammerstones (fig. 9).—Waterworn cobblestones, usually of ande- 
site, showing a battered edge, have been classified as hammerstones. 
Size varies considerably; length is 5-10 cm., width from 4-8 cm. 
The surfaces are usually badly eroded, especially the battered edge. 
Hafted hammerstones (fig. 10).—Three hammerstones from N-11 
have been pecked at the center on opposite sides to form a depression 
for hafting. They measure roughly 11 cm. long by 5 cm. wide, with 
the pecked area 3-4 cm. wide and the depression 5-8 mm. deep. The 
