Vegetation /ones, ami tO the mud- 

 flats which extend [or mote than a 

 mile in front of the mangrove fringe, 

 down to low spring tide level. I he 

 mii lace bOpOJTaph) here was sur- 

 veyed in relation 16 vegetation zones 

 and tidal levels and sub sin lace 

 features were deduced from an 

 examination of the dredged material 

 and frOBI probing the marshland: the 

 results ate shown in Fig. 2. 



I lie inudtlals have heen colonised 

 hy Avicctmitt mm inn dowu almost 

 to mid-lidO level Mangroves occupy 

 the -'»nc between this level ami the 

 line reached by mean high spiing 

 tides, where they give place to salt 

 marsh, dominated bv ■i'llnoiihinnin 

 in the outer zone, with $gtfi prtttu 

 fand some bare or algal-carpeied 

 saline Hals) to landward, suhmci ycd 

 only iluiing the highest Spring tide-, 

 which just reach the bordering A/i7</- 

 fOtCtt •■uifolui /one. The vegetation 

 grows upon a depoMtioual terrace 

 ol Mtft muddy scdimcnl I con I am iih: 

 layers of peat and shells), which 

 rests in turn on an uudulaime lloo, 

 of quanzosc sand, continuous with 

 the low sanilv ridges healing wood 

 land, dominated by /Tw^/v/""* 

 rw/i'v, which form the immediate 

 hinterland 



These low sandy ndges originated 

 as beach ridges, several of which 

 tei inmate laterally in recurved sand 

 spits now enclosed by marshland 



Ibis sector of the shore of Wesi nn 

 port Bay was evidently sandy aboui 

 five thousand years ago, when tjj 

 sea attained its present level , lric . 

 the late Pleistocene low sea [eW 

 episode (el Hud IMIS8, p. 45 ), | 

 muddy sediment, derived from i,,,,. 

 dial washed into Wcsternport Ba\ 

 by livers, together with OrgSl 

 inaienals deiived from the estuarinc I 

 shell fauna and |)lanl remains, |m I 

 accumulated here subsequently. 



Hie Yarmga shore thus provides 

 good site to examine whethei n L 

 patteiu of sediment uceumuU».. 

 has been iletei milled bv eolomvm lt , 

 and advance ol mangroves. tt 

 whether the mangroves have simp 1 , 

 spread lorward in a pattern deter- 

 mined hy the independent iccum 

 laiiou ot sediment It is also a goo,i 

 site for an investigation ol rates wid 

 patients ol veitical accretion in M 

 around the mangroves. 



MsNC.KDVtS AND StlOtUiLlNr- 

 A|)VAN( L 



A l icrnnm ituinnu grows in u zone 

 which is at least panly submerged ij 

 eveiy high lide. bill stands above 

 watei level lot sevetal hours before 

 .aid .dler low title lhc advance of 

 mangroves appears to be limited hi 

 ila depth and duration of tidal Ngt 

 miif.iuc Dm my the wiuler thcu 

 are often targe numbers of maitgim. 

 sccdltnjis in the mud in front ot th< 

 m.mgiove lunge in Weueinport Bay 



Flsorc 2 Section tit Yarioga 



192 



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Vicl Not. Vol B6 



