PHYSICAL HISTORY OF THE AMAZONS. 435 
bare on both sides of the Igarap Grande by the encroach- 
ments of the ocean. That this is the work of the sea is un- 
deniable, for all the little depressions and indentations of the 
peat are filled with sea-sand^ and a ridge of tidal sand divides 
it from the forest still standing behind. Nor is this all. At 
Vigia, immediately opposite to Soure, on the continental 
side of the Pard River, just where it meets the sea, we have 
the counterpart of this submerged forest. Another peat-bog, 
with the stumps of innumerable trees standing in it, and 
encroached upon in the same way by tidal sand, is exposed 
here also. No doubt these forests were once all continuous, 
and stretched across the whole basin of what is now called 
the Para River. 
Since I have been pursuing this inquiry, I have gathered 
much information to the same effect from persons living on 
the coast. It is well remembered that, twenty years ago, 
there existed an island, more than a mile in width, to the 
northeast of the entrance of the Bay of Vigia, which has 
now entirely disappeared. Farther eastward, the Bay of 
Braganza has doubled its width in the last twenty years, 
and on the shore, within the bay, the sea has gained upon 
the land for a distance of two hundred yards during a 
period of only ten years. The latter fact is ascertained 
by the position of some houses, which were two hundred 
yards farther from the sea ten years ago than they now 
are. From these and the like reports, from my own ob- 
servations on this part of the Brazilian coast, from some 
investigations made by Major Coutinho at the mouth of 
the Amazons on its northern continental shore near Ma- 
capa, and from the reports of Mr. St. John respecting the 
formations in the valley of the Paranahyba, it is my belief 
that the changes I have been describing are but a small 
