1 86 APPENDIX. 
I began to cut off part of it with chiffels ; and in feparating 
from the mafs twenty-five or thirty pounds, I fpoiled all the 
chiffels I had, to the number of feventy. 
I ordered my men to dig round it, and found the under fur- 
face covered with a coat of fcoriae from four to fix inches thick 5 
undoubtedly occasioned by the moiffure of the earth, becaufe 
the upper furface was clean. 
Having moved it half round, by me'ans of handfpikes, I 
ordered the ground under its bed to be dug to a considerable 
depth, and even blew it up in two places with gunpowder ; 
after which, examining the deepeft part of the earth, I found 
it exa&ly like the upper part, and of the fame nature as the 
earth of all the country, as likewife of two pits, which I 
had dug at the dillance of feventy or one hundred paces E. 
and W. of the mafs. Finding here no root or trace of gene- 
ration, I reafoned in the following manner. 
Either this mafs was produced in the Spot where it lies, or 
it was conveyed hither by human art, or caff hither by fome 
operation of nature. It could not be generated here, accord- 
ing to any known procefs of nature. And whence, by whom, 
or how, could it be conveyed hither, as there are no iron 
mines within hundreds of leagues, nor remembrance that any 
have been worked in the kingdom ? It could be of no value. 
Since it could not be ufed ; and why bring it into a country 
the moft uninhabitable of all the Chaco, from the want of 
water ? Befides, how could fo heavy a mafs be conveyed, 
the Indians never having known the ufe of wheel carriages ? 
This mafs, therefore, muff have been the effect of fome 
volcanic explofion. 
, Many circumSlances induce me to think fo. Volcanos fre- 
quently leave behind them, after exploSion, pits of water, 
1 either 
JF \ f % 
