26 MOZAMBIQUE 



to garner the harvest of the sea. At first it is 

 a struggle between them ; the creeping plants 

 advancing to anchor themselves in the shifting 

 sands often to perish, though, through their re- 

 serves, ultimately to prevail. During the contest 

 the opposing forces have piled up between them 

 a sand-dune. 



Sometimes the dune thus formed takes the form 

 of a long tongue of sand or island behind which 

 the sea penetrates. In the course of time this 

 newly formed bank effects a junction with a 

 neighbouring accumulation, and the intruding 

 water of the ocean becomes imprisoned. This 

 would seem to be the origin of the numerous 

 brackish lakes in the district of Inhambane. The 

 course of the Incomati and that of several other 

 rivers which take a turn and run parallel to the 

 coast before entering the sea have been manifestly 

 influenced by these sand barriers. 



The scour caused by the great rivers accounts 

 for the slow accumulation of sand near their 

 mouths, the currents being a disturbing element 

 and interrupting the work of the waves and the 

 wind. Sand brought down from the remote in- 

 terior and subsiding forms bars and shoals and 

 banks. Some of it is carried away by the tide 

 drift and the Mozambique current, providing the 

 waves and the wind with material for their work 



