bulletin: museum of comparative zoology. 



PAGE 



IV. Conclusions regarding the Forms and Struct ore of the 



Stone Reefs 104 



The shore beach 105 



Tlie off-shore beach 105 



Application to the Brazilian stone reefs 107 



Structure of the stone reefs 108 



Conclusions 110 



V. The Elevation and Depression of the Northeast Coast of 



Brazil Ill 



Changes of the reefs within historic times Ill 



Observations of others Ill 



Have there been changes within the historic period ? 114 



Conclusions 117 



Changes within recent geologic periods 118 



Views of former writers 118 



"^ The schistose structure of the reef rocks 119 



The dip of the reef rocks 119 



Reef rocks above high tide 120 



Lakes near the coast 121 



The fixed dunes of the coast 121 



Islands joined to the mainland 122 



The straightening of the coast-line 124 



Comparative effects of elevation and depression 125 



EfTects of elevation 125 



Effects of depression 125 



Forms on a stationary coast 127 



Application to Brazil 127 



Evidences of depression 127 



Open bays 128 



Coast lakes 129 



Rios tapados 134 



Choked embayments 137 



Depressed valleys 139 



The case of Rio Sao Francisco 143 



Evidence of the islands 144 



Off-shore clays 144 



Evidence of buried rock-channels 145 



Additional views of depression 146 



Evidences of elevation 148 



Elevated beaches, State of Alagoas 148 



Elevated beaches, State of Bahia 149 



Marine terrace at Ilheos, Bahia 153 



Lagoa de Itahype 155 



At Ponta d'Areia, Bahia 156 



At Victoria, Espirito Santo 158 



Elevated sea-urchin burrows 159 



The death and decay of the coral reefs 159 



Time relations of the elevations and depressions 162 



Influence of the coral reefs 164 



Influence of the mangues 167 



Hyacinths 167 



Origin of the coast sands 167 



