LAND FORMS, THEIR DEFORMATION AND FORMATION 



53 



the present discussion, the effects of waves on certain 

 shorelines and some of the land forms produced will 

 be discussed. 



SHORELINE OF EMERGENCE 



Initial Stage. When land first rises above the sea, 

 there is revealed a relatively straight, new shoreline 

 and a gently sloping shore profile of unconsolidated 

 sediments. The gradual slope of the land continues 

 for some distance out into the sea. 



This picture soon is altered by wave action. Waves 

 and undertow pick up unconsolidated sediments, and 

 the sediments are deposited offshore where the waters 

 lose much of their energy. Because waters at that off- 

 shore point have less energy, sediments are deposited 

 and accumulate as a ridge, or offshore bar, that even- 



tually extends above sea level. Between the bar and 

 the ridge, the waters are contained in a lagoon (Fig- 

 ure 4. 16). 



Youth. Along the shoreline, the lagoon starts to fill 

 with stream sediments and salt marsh vegetation. At 

 the same time, wave action continues to deposit ma- 

 terials on the outside of the bar and winds carry sand 

 on over the bar into the lagoon. These two conditions 

 cause the tidal marsh to grow seaward and the bar to 

 grow landward. At the up-and-down shore margins 

 that enclose the area of emergence, the bar merges 

 with the land. Here, the activities of tidal marsh and 

 bar growing toward one another soon constrict to the 

 point of producing a tidal creek. Further growing 

 together of marsh and bar progresses toward the cen- 

 ter of the area of emergence, constricts the tidal creek, 

 and finally fuses the marsh and bar. Ultimately, this 



bar migration 







bar growth 









: JUST BEFORE 

 • MATURITY 



Figure 4.16 Development along a shoreline of emergence. 



