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 



