brannek: the stone reefs of brazil. 275 



This fauna is more closely related to that of the West Indies than to any 

 other now known. 



The dead coral reef rock is being changed to dolomite by the replace- 

 ment of a part of the calcium by magnesium from the sea water. 



No recent coral reefs elevated above tide-level are known on the 

 coast of Brazil. There are, however, satisfactory evidences of a late ele- 

 vation of the coast amounting to about two metres. At many places 

 dead coral reefs are buried beneath sands and other mechanical accumu- 

 lations brought down from the land. 



The coral reefs have been an important protective and constructive 

 factor in controlling the outlines of the Brazilian coast. Some of the 

 small harbors of the coast are formed by coral reefs : such are Maceio 

 and Tamandare. The sand beaches and spits have also, under the pro- 

 tection of the reefs, extended themselves seaward, and even encroached 

 upon and buried some of the coral reefs themselves. 



