and -there can be no doubt that in nunerous -ases tun- 
neling was continued a orison tally or oh 11 uely for con- 
siderable distances along productive Layers • The heaps 
and ridges of debris thxxera out are. rarely above ten 
feet in height, but they are //ell-pronounced and abrupt, 
ShfjjfvL-* 
and the total irregularities of the &&re are so great that 
exploration is tedious and difficult* Very generally the 
debris is intermingled with broken obsidian, and in many 
eases it seems to consist almost exclusively of broken 
fragments and -flakes left by the workmen engaged in re«©h- 
ting-oui the forms desired. In places there are large heaps 
of flakes vrherc the choice fragment© of stone were brought 
from the mines pad place? in the hands of the f lakers to be 
worked *u|a0 
Extensive areas are covered ./Ith these deposits of 
