408 A JOURNEY IN BRAZIL. 
America, of Azoic, Silurian, Devonian, and Carboniferous 
formations, shored up against each other by the gradual 
upheaval of the continent; although, unquestionably, older 
palaeozoic and secondary beds underlie, here and there, 
the later formations. Indeed, Major Coutinho has found 
paleozoic deposits, with characteristic Brachiopods, in the 
valley of the Rio Tapajos, at the first cascade, and car- 
boniferous deposits have been noticed along the Rio 
Guapore and the Rio Mamore. But the first chapter 
in the valley's geological history about which we have 
connected and trustworthy data is that of the cretaceous 
period. It seems certain, that, at the close of the secondary 
age, the whole Amazonian basin became lined with a cre- 
taceous deposit, the margins of which crop out at various 
localities on its borders. They have been observed along 
its southern limits, on its western outskirts along the 
Andes, in Venezuela along the shore-line of mountains, 
and also in certain localities near its eastern edge. I well 
remember that one of the first things which awakened 
my interest in the geology of the Amazonian Valley was 
the sight of some cretaceous fossil fishes from the province 
of Ceara. These fossil fishes were collected by Mr. George 
Gardner, to whom science is indebted for the most ex- 
tensive information yet obtained respecting the geology 
of that part of Brazil. In this connection, let me say 
that I shall speak of the provinces of Ceara, Piauhy, and 
Maranham as belonging geologically to the valley of the 
Amazons, though their shore is bathed by the ocean and 
their rivers empty directly into the Atlantic. But I 
entertain no doubt that, at an earlier period, the north- 
eastern coast of Brazil stretched much farther seaward 
than in our day ; so far, indeed, that in those times the 
