Chap. I] 



THE FORMATIONS 



187 



5and, and gradually hutiuis, accumulates round these groups of plants, 

 ;o that in time they form the centre of little sand}' liillocks, termed 

 touradons,' only about a decimeter high. 



The touradons, thank-s to the mattiiii;" of the roots and stolons, already 

 )Ossess considerable powers of resistance and can witlistand even the 



inter floods. Every year they increase in breadth, so that after a few 

 ■ears they attain a diameter of one to two meters and already support 

 ibout twenty species of halophytes, among others Inula crithmoides, species 

 f Juncus, Statice, Plantago, and several grasses. Slowly, continLially 



IG. loi. From the C.iniargue. Horizontal sandy flats liable to be flooded by storm-tides, with the 

 earliest vegetation of Salicornia macrostachya. After Flahault and Combres. 



ruggling against the floods, the touradons gradually raise the soil, 

 hilst the rain continually sweetens them and renders them suitable for 

 le growth of non-halophytes. 



The dunes in the Camargue are also very instructive. In some parts 

 ' the coast they form parallel ridges separated, valley-like, by the 

 nginally flooded tract with its touradons. Their vegetation constantly 

 icreases inland. Evidently there was once a general upheaval of the 



ound ; and dunes as well as touradons have remained as geological 

 irvivals. The succession of the dunes exhibits all intermediate stages, 

 om the commencement of vegetation on the outermost dunes to the 



