AMAZONS ESTUARY. 



101 



south of Marajo Island the estuary ramifies into a labyrinth of creeks and chan- 

 nels, which merge in another estuary, that of the E,io Tocantins. At first sight 

 all these fluvial waters might seem to belong to the Amazonian system. But the 

 Amazons and Tocantins currents do not intermingle, or at least they do so to 

 a scarcely appreciable extent. Nevertheless, the western creeks through which 

 the Amazons communicates with the Rio Para are flooded by the waters of the 

 great river. Thus a small portion of the larger current would appear to join that 



Fig. 34. — Amazonian Gulf. 

 Scale 1 : 13,000,000. 



Oto5 

 Fathoms. 



Oto 650 

 Feet. 



Depths. 



5 to 100 



Fathoms. 



Heights. 



100 Fathoms 

 and upwards. 



650 Feet 

 and upwards. 



310 Miles. 



of the Tocantins, and the Rio de Para might in a sense be taken for one of the 

 mouths of the Amazons. 



In the interior the sandstones of the Amazonian basin crumble away under 

 the action of winds, rains, sun, and vegetation. But on the seaboard and in the 

 islands of the estuary they are further exposed to the incessant attacks of the 

 Atlantic waves. Both geology and contemporary history show that the sea 

 is here steadily encroaching on the land, swallowing up islets, eating away the 

 shores of islands and headlands. Thus the coast of Macapa on the north side 

 of the estuary has considerably receded since the beginning of the century ; 

 41 



