374 A JOURNEY IN BRAZIL. 
The only thing he may be tempted to take will be a canoe 
and a pair of oars : with these an Indian is rich. He only 
wants to get back to his woods ; and he is deterred by no 
sentiment of affection, or consideration of interest. 
To-day we are passing the hills of Almeyrim. The last 
time we saw them it was in the glow of a brilliant sunset ; 
to-day, ragged edges of clouds overhang them, and they aie 
sombre under a leaden, rainy sky. It is delightful to Mr. 
Agassiz, in returning to this locality, to find that phenomena, 
whiui were a blank to him on our voyage up the river, are 
perfectly explicable now that he has had an opportunity of 
studying the geology of the Amazonian Valley. When we 
passed these singular flat-topped hills before, he had no clew 
to their structure or their age, whether granite, as they have 
been said to be, or sandstone or limestone ; whether primi- 
tive, secondary, or tertiary : and their strange form made the 
problem still more difficult. Now he sees them simply as 
the remnants of a plain which once filled the whole valley of 
the Amazons, from the Andes to the Atlantic, from Guiana 
to Central Brazil. Denudations on a colossal scale, hitherto 
unknown to geologists, have turned this plain into a laby- 
rinth of noble rivers, leaving only here and there, where the 
formation has resisted the rush of waterLs, low mountains 
and chains of hills to tell what was its thickness.* 
February ~Lst. On Tuesday evening we reached Porto do 
Moz, on the river Xingu, where we had expected to be de- 
tained several days, as Mr. Agassiz wished especially to 
obtain the fishes from this river, and, if possible, from its 
upper and lower course, between which rapids intervene. 
He found, however, his harvest ready to his hand. Senhor 
Yinhas, with whom, when stopping here for a few hours 311 
* See Chapter XIII., on the Physical History of the Amazons. 
