248 



PHYSICAL GEOLOGY 



FIG. 266. A bar. Sea cliffs in distance. 



completely, forming a loop. Many spits have been built en- 

 tirely across the mouths of harbors, and joined to the beach 

 beyond. Such completed spits are fears (Fig. 266). Bars 

 sometimes connect islands with the mainland, thus making 

 land-tied islands. Plate XIV shows spits, hooks, bars, land- 

 tied islands, etc., on the coast of Long Island. 



Barrier islands. Storm waves drag on shelving bottoms 

 at some distance from the shore. They drop most of their 

 load where they break, along a line roughly parallel with the 



FIG. 267. Diagram of barrier islands and lagoon. 



FIG. 268. Diagram showing a later stage in the development of the coast 

 represented by Figure 267. Dunes have formed on the barrier islands. 

 Marshes cover much of the area of the lagoon. 



