COMPOSITION OF PERNAMBUCO REEF 3 



Record of a Boring on the Pernambuco Stone Reef 



Meters 



Hard reef rock 2.95 



White sand 1.22 



Shells 1.10 



Gray sand 0.65 



Broken rock 1 .22 



Dark sand 2. 10 



Mottled clay 1.80 



Yellow clay 0.70 



Gray sand . ... 3.50 



White sand 2.20 



In another bore the hard reef rock at the top was found to be about 

 4 meters thick ; otherwise the records of the two other holes closely 

 resemble this one. It is not known what is meant in the record by 



Figure 1. — Bird's-eye View of the Region about Traigao and the Mouth of Rio Mamanguape. 

 Showing the relations of the stone reef to the shore. 



11 broken rock." In none of the holes was there any repetition, at greater 

 depth, of the hard top rock; the underlying materials were either clays 

 or they were loose and frag mental. 



The reefs are off the shore a little way and approximately parallel 



