122 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
coast both north and south of Natal, 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 Cunhahú. 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 Ceará 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 Ceará dunes are sometimes three hundred palms 
high? and Hawkshaw 8 notes that they “stretch for miles on each side 
of the city of Ceará,” while at Maranhäo, 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 the 
dunes ; the sand is driven toward the west until it comes to a river and 
there it falls.” 4 | 
6. Islands 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 ? 
If we imagine the Pernambuco coast elevated an amount equal to or 
1 Pompeo de Souza Brasil. Ensaio estatistico da provincia do Ceará. Т., р. 10-11. 
J. E. Wappxus. А geographia physica do Brasil, р. 15. Rio, 1884. 
2 Trabalhos da Commissäo scientifica de Exploração. І. Introducção, 1802, p. 
CXXXVi-Vil. 
® Melhoramento dos portos do Brazil, Relatorio de Sir John Hawkshaw, р. 80- 
81, 91. Rio de Janeiro, 1875. 
^ J. E. Wappeus. A geographia physica do Brazil refundida, р. 15. Rio de 
Janeiro, 1884. 
