2H THE POPULAR SCIENCE MONTHLY. 



But, instead of adding to what has already been written upon 

 this subject, I will quote a few words from two writers, whose 

 descriptions are entirely trustworthy : " All that we hear or read 

 of the extent of the Amazons and its tributaries fails to give an 

 idea of its immensity as a whole. One must float for months 

 upon its surface in order to understand how fully water has the 

 mastery over land along its borders. Its watery labyrinth is 

 rather a fresh- water ocean, cut up and divided by land, than a 

 network of rivers. Indeed, this whole valley is an aquatic, not a 

 terrestrial basin." * 



" This belt . . . can not be called either land or sea, island or 

 archipelago. It is a veritable labyrinth of streams, canals, gulfs, 

 islands, and lakes, combined in such a fashion as to impress one 

 as to the caprice of man rather than as the work of Nature." f 



This vast expanse of muddy water, bearing out into the ocean 

 immense quantities of sediment ; the pororoca, breaking so vio- 

 lently on the shores, and carrying away the coarser material to 

 the open sea, and burying uprooted forests beneath newly formed 

 land ; the rank vegetation of islands and varzea rapidly growing 

 and as rapidly decaying in this most humid of climates; the 

 whole country submerged for a considerable part of the year by 

 the floods of the Amazon impress one with the probability of 

 such phenomena having been in past ages, and still being, geologi- 

 cal agents worthy of study and consideration. Across the mouth 

 of the Amazon, a distance of two hundred miles, and for four 

 hundred miles out at sea, and swept northward by ocean-currents, 

 beds of sandstone and shale are being rapidly deposited from 

 material some of which is transported all the way from the 

 Andes, while in many places dense tropical forests are being 

 slowly buried beneath the fine sediment thrown down by the 

 muddy waters of the great river. 



So many random and erroneous statements concerning the 

 pororoca have been made by writers upon Brazil that I take this 

 occasion to refer to and correct some of the most glaring of them. 



Prof. William H. Edwards, who visited the Amazon region in 

 1846, has made way with it altogether, and says that " no one 

 knows of such terrible phenomena nowadays," although he " in- 

 quired of several persons accustomed to piloting in the main 

 channel, and of others long resident in the city of Para\" But, 

 with the exception of a very few who have business relations in 

 that direction, the people of the city of Par&, as a rule, know as 

 little of the northern mouth of the Amazon as they do of the 



* A Journey in Brazil, by Prof, and Mrs. Louis Agassiz, p. 256. 



f Mnjor Joao Martins da Silva Coutmho, in the Bulletin de la Societe de Geographic, 

 October, 1867, p. 330. 



