406 A JOURNEY IN BRAZIL. 
Coutinho, a member of the Brazilian government corps 
of engineers, who, by the kindness of the Emperor, was 
associated with me in my Amazonian expedition. I can 
truly say that he has been my good genius throughout the 
whole journey, saving me, by his previous knowledge of the 
ground, from the futile and misdirected expenditure of 
means and time often inevitable in a new country, where 
one is imperfectly acquainted both with the people and 
their language. We have worked together in this investi- 
gation ; my only advantage over him being my greater 
familiarity with like phenomena in Europe and North 
America, and consequent readiness in the practical hand- 
ling of the facts and in perceiving their connection. 
Major Coutinho's assertion, that on the banks of the Ama- 
zons I should find the same red, unstratified clay as in Rio 
and along the southern coast, seemed to me at first almost 
incredible, impressed as I was with the generally received 
notions as to the ancient character of the Amazonian de- 
posits, referred by Humboldt to the Devonian, and by 
Martins to the Triassic period, and considered by all 
travellers to be at least as old as the Tertiaries. The 
result, however, confirmed his report, at least so far as the 
component materials of the formation are concerned ; but, 
as will be seen hereafter, the mode of their deposition, and 
the time at which it took place, have not been the same at 
the north and south ; and this difference of circumstances 
has modified the aspect of a formation essentially the same 
throughout. At first sight, it would indeed appear that 
this formation, as it exists in the valley of the Amazons, is 
identical with that of Rio ; but it differs from it in the 
rarity of its boulders, and in showing occasional signs of 
stratification. It is also everywhere underlaid by coarse, 
