390 A JOURNEY IN BRAZIL. 



during the last eighteen or twenty years, the beach had re- 

 ceded considerably in some places ; the high-water line being 

 many yards beyond its former limit. The result of this ex- 

 cursion has shown that, with the exception of some low mud- 

 islands nearly level with the water, all the harbor islands 

 lying in the mouth of the Amazons are, geologically 

 speaking, parts of the Amazonian Valley, having the same 

 structure. They were, no doubt, formerly continuous 

 with the shore,' but are separated now, partly by the fresh 

 waters cutting their way through the land to the ocean, 

 partly by the progress of the sea itself. 



March 2tk. Our quiet life at Nazareth, though full of 

 enjoyment for tired travellers, affords little material for a 

 journal. A second excursion along the coast has furnished 

 Mr. Agassiz with new evidence of the rapid changes in the 

 outline of the shore, produced by the encroachment of the 

 sea. So fast is this going on that some of the public works 

 near the coast are already endangered by the advance of 

 the ocean upon the land. During the past week he has 

 been especially occupied in directing the work of a photo- 

 graphist employed by Senhor Pimenta Bueno, who, with his 

 usual liberality towards the scientific objects of the expedi- 

 tion, is collecting in this way the portraits of some remark- 

 able palms and other trees about his house and grounds. 

 One of the most striking is a huge Sumaumera, with but- 

 tressed trunk. These buttresses start at a distance of about 

 eight or ten feet from the ground, spreading gradually to- 

 ward the base ; they are from ten to twelve feet in depth. 

 The lower part of the trunk is thus divided into open com- 

 partments, sometimes so large that two or three persons can 

 stand within them. This disposition to throw out flanks or 

 wings is not confined to one kind of tree, but occurs in 



