122 BULLETIN : MUSEUxM OF COMPARATIVE ZOOLOGY. 



coast both north and south of ^atal, and at this last place efforts have 

 been made by the government for years to prevent the dunes from 

 filling up and destroying the harbor. 



North of the village of Bahia Formosa moving sand dunes form the 

 coast as far as the mouth of Rio Cunhahu. Some of these dunes 

 rise to a height of sixty metres and are now blowing inland. Ordi- 

 narily they are about twenty metres high, and the sand is blown inland 

 over a caatinga forest. 



A score or more of instances might be given of the movement of the 

 dunes of the coast of Rio Grande do Norte. These, however, must 

 serve, especially as the validity of the argument based upon their being 

 fixed is not recognized. 



Pompeo de Souza Brasil observes that the dunes of Ceara are always 

 in motion, " so that the coast is ever changing its aspect." In some 

 places he says the dunes extend for leagues into the interior and even 

 close the mouths of streams and turn them into lakes. -^ 



Capanema says the Ceara dunes are sometimes three hundred palms 

 high ^ and Hawkshaw ^ notes that they " stretch for miles on each side 

 of the city of Ceara," while at Maranhao, Ponta d'Areia, ''the soldiers of 

 the fort have much difficulty in keeping themselves from being en- 

 gulfed " in sand. 



" A curious circumstance of this part of the coast (northeast Brazil) 

 is that all the western sides of the river mouths are covered with vege- 

 tation and mangrove swamps, while the eastern sides are barren sand 

 wastes. This is caused by the constant action of the east wind on tlie 

 dunes ; the sand is driven toward the west until it comes to a river and 

 there it falls." * 



6. I.^Iands joined to the mainland (Capanema). — A study on the 

 ground of the physical geography of the Brazilian coast makes it plain 

 that former islands have, within geologically recent times, been joined 

 to the mainland. But such joining cannot alone be accepted as evidence 

 of an elevation ; the question is, how was this joining brought about 1 



If we imagine the Pernambuco coast elevated an amount equal to or 



1 Pompeo de Souza Brasil. Ensaio estatistico da provincia do Ceara. I., p. 10-11. 

 J. E. Wappteus. A geographia physica do Brasil, p. 15. Rio, 1884. 



2 Trabalhos da Coramissao scientifica de Explorayao. I. Introduc5ao, 1862, p. 

 cxxxvi-vii. 



3 Mellioramento dos portos do Brazil, Relatorio de Sir John Hawkshaw, p. 80- 

 81, 91. Rio de Janeiro, 1875. 



* J. E. Wappa^us. A geographia physica do Brazil refundida, p. 15. Rio de 

 Janeiro, 1884. 



