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At and near the point of the Bay, the reef is interrupted by 

 the rocky and bold headland, and in fact wherever natural 

 rocks protruded into the sea, there was no reef ; on the other 

 hand, wherever the present coast is sandy, there the reef pre- 

 vails. Again, wherever I found the shore steep, the reef lay 

 within a few yards, but where it was flat or gently shelving, 

 the reef was at a greater distance. Near Bahia the consti- 

 tuents of the reef are a fine white quartz sand, with a few 

 grains of mica and some carbonate of lime, which correspond 

 exactly with the white sand of the hills or downs known to 

 navigators by the name of the Lencas, or white sheets of 

 Bahia. These sandhills are a striking characteristic of the 

 northern coast of the Brazils, and with a few intervals in the 

 provinces of Pernambuco and Alagoas, they give the country, 

 as seen from the sea, a most dreary and uninviting aspect. 

 Between Cape Sao Roque and Maranham these downs rise 

 into hills 300 or 400 feet in height, glistening in the rays of a 

 burning sun, without a blade of vegetation upon them for 

 miles. And thus should a fresh induration take place, the 

 present coast line affords the same elements for the formation 

 of a modern reef as no doubt existed at an earlier period; 

 and when formed, the unstable sand behind it would likewise 

 as easily be washed away, and other harbours would be formed 

 similar in all respects to those we now find in the Brazils. 



That the reef is not so durable as some suppose, is shown 

 by the disintegration that is always going on in Pernambuco 

 Harbour, caused no doubt in some measure by the action of 

 the fresh water upon the calcareous particles mixed with the 

 sand. It sinks down on the inner side in large masses of 

 many tons, which are gradually broken up aud carried away 

 by the tide. It would therefore be highly important for the 

 interests of the harbour to keep it in repair, for at the same 

 rate of destruction that has gone on for the last 150 years, it 

 would not require many centuries to destroy its utility. 



To shew that such indurations of the coast are not un- 



