164 
PHYSICAL HISTORY OF THE 
separate journeys. Recently, Mr. St. John 
and myself having met at Para on returning 
from our respective journeys, I have had an 
opportunity of comparing on the spot his geo¬ 
logical sections from the valley of the Piauhy 
with the Amazonian deposits. There can be 
no doubt of the absolute identity of the forma¬ 
tions in these valleys. 
Having arranged the work of my assistants, 
and sent several of them to collect and make 
geological examinations in other directions, I 
myself, with the rest of my companions, pro¬ 
ceeded up the coast to Para. I was surprised 
to find at every step of my progress the same 
geological phenomena which had met me at 
Rio. As the steamer stops for a number of 
hours, or sometimes for a day or two, at 
Bahia, Maceio, Pernambuco, Parahiba, Natal, 
Ceara, and Maranliam, I had many oppor¬ 
tunities for observation. My friend Major 
Coutinho, already an experienced Amazonian 
traveller, first told me that this formation con¬ 
tinued through the whole valley of the Ama¬ 
zons, and was also to be found on all of its 
affluents visited by him, although he had never 
thought of referring it to so recent a period. 
