178 
PHYSICAL HISTORY OF THE 
the water basin had now changed, and as if 
the waters under which this second formation 
was deposited had vibrated between storm and 
calm, — had sometimes flowed more gently, 
and again had been tossed to and fro, — giv¬ 
ing to some of the beds the aspect of true 
torrential deposits. Indeed, these sandstone 
formations present a great variety of aspects. 
Sometimes they are very regularly laminated, 
or assume even the appearance of the hardest 
quartzite. This is usually the case with the 
uppermost beds. In other localities, and more 
especially in the lowermost beds, the whole 
mass is honeycombed, as if drilled by worms 
or boring shells, the hard parts enclosing 
softer sands or clays. Occasionally the ferru¬ 
ginous materials prevail to such an extent, 
that some of these beds might be mistaken for 
bog ore, while others contain a large amount 
of clay, more regularly stratified, and alternat¬ 
ing with strata of sandstone, thus recalling the 
most characteristic forms of the Old Red or 
Triassic formations. This resemblance has, 
no doubt, led to the identification of the Ama¬ 
zonian deposits with the more ancient forma¬ 
tions of Europe. At Monte Alegre, of which 
