750 REVIEWS 



5. The straightness of the coast-line is due to the long period of wearing to 

 which the coast has been subjected, and to the constant on-shore winds and 

 waves along the coast. 



6. During the dry season the waves of the sea are able to close the mouths 

 of many of the weaker streams. 



7. At such times only the large streams are able to keep their mouths boldly 

 open. 



8. Although no changes of level are known to have taken place within the 

 historic period, there are evidences of both elevation and depression of the Brazihan 

 coast in late geologic times. 



9. The evidences of depression consist of: 



a) The open bays: Rio de Janeiro and Bahia. 



b) The partly choked up bays, such as Santos and Victoria. 



c) The coast lakes formed by the closing of the mouths of estuaries, such 

 as Lagoa Manguaba, Lagoa do Norte, Jiquia, Sinimbu, etc. 



d) Embayments altogether filled up. 



e) The islands along the coast are nearly all close in-shore and have the 

 appearance of having been formed by depression of the land. 



/) The buried rock channels at Parahyba, now filled with mangrove swamps 

 and mud, show a depression of at least twelve meters since those channels were 

 cut. 



g) Wind-bedded sand below tide-level on Fernando de Noronha. 



10. The evidences of elevation consist of: 



a) Elevated sea beaches, especially well shown about the Bay of Bahia, and 

 along the coast of the state of Bahia. 



b) Marine terraces about Ilheos in the state of Bahia. These are about 

 eight meters above tide-level. 



c) Horizontal lines of disintegration about one meter above high tide in 

 granites and gneisses at and about Victoria, state of Espirito Santo. 



d) Burrows of sea-urchins so far above low tide that sea-urchins cannot now 

 live in them. These are well shown at Pedras Pretas on the coast of Pemambuco. 



11. Of the two movements the depression has been much the greater and 

 was the earlier. 



12. The great depression probably took place in early Pliocene times (see 

 chapter on Geology, pp. 8-33). 



13. Following the Pliocene depression of the coast, the headlands were 

 strongly eroded, the mouths of bays and estuaries were closed, and the coast line 

 was straightened. 



14. The standstone reefs of the coast were formed and hardened subsequent 

 to the depression. 



15. The coral reefs of the coast have helped build out the shores, and they 

 have likewise protected the land from the destructive action of the waves. 



16. The stone reefs have also protected the land, and have helped to prevent 

 the encroachment of the sea. 



