348 Prof. Hartt on the Brazilian Sandstone Reefs. — [June, 
treats of “the recife, a singular ridge of coral rock,” bordering 
the coast, at a distance from it of about half a mile to three miles 
or more, and extending from the north-east part of Brazil to south 
of Bahia. According to his accounts, the reef is about sixteen 
feet broad at the top, forming a natural breakwater, with smooth 
and shallow water inside, affording a channel for coasters. “It is 
broken occasionally, and forms, by the openings, entrances to the 
greater part of the ports, rivers and creeks on the coast. 
_ Gardner describes the mythical reef in nearly the same terms, 
and there can be no doubting the fact that these two writers have 
reproduced Piso’s old description, with many additional details 
thrown in gratuitously. 
It is needless to state that these accounts of a continuous reef 
were without foundation, but they served, more or less, to mould 
the world’s ideas of the character of that coast up to the time 
when the late Prof. Ch. Fred. Hartt published the results of his 
careful and painstaking explorations of that region. Whether 
this observer was the first to rightly interpret the structure of the 
Central Brazilian coast or not, he, at least, has given the only 
extended and intelligible account of it. He has shown that 
although stone reefs occur at many localities, they are far from 
being universal, or even continuous over any great distance. 
Quite distinct from these are a series of coral reefs, often lying 
near the shore, but much more developed farther out, rising up- 
ward from the surface of the submerged border of the conti- 
nent. 
As a member of the Thayer Expedition in 1865, Prof. Hartt 
examined two quite perfect stone reefs, at Porto Seguro and 
Santa Cruz, in the province of Bahia, and at several places in the 
province of Espirito Santo he also found traces of the same 
structure, lying near the beach, however, and not forming true 
reefs. On his second trip, in 1867, he was able to study the 
larger and more perfect stone reef of Pernambuco, and to detect 
a similar formation on the beaches about Bahia. A full state- 
ment of these investigations, and of his theory of the origin of 
the reefs, is given in his “Geology and Physical Geography of 
Brazil,” published in 1870. Darwin, who touched at Pernambuco 
on his memorable voyage, arrived at nearly the same conclusions 
regarding the mode of formation of the reef at that place, as did 
Prof. Hartt, but his description of it is very brief. 
