.'J6\8 Proceedings Portland Society Natural History 



The upper beach, especially in the more exposed places 

 is likewise very stony and resembles the middle beach in both 

 its structure and vegetation (Figure 20). In the case of 

 barrier beaches there is a well developed crest on this beach. 

 Growing on the seaward side of this crest, where the boul- 

 ders and cobbles are larger, are the species mentioned above ; 

 while on the leeward side, where the rocks are ordinarily 

 smaller, other forms are frequent. Prominent among these 

 may be mentioned : 



Kibes hirtellum Rhus Toxicodendron 



Rosa humilis Oenothera muricata 



Geranium Robertianum Achillea Millefolium 



Where a shingle beach borders on an upland of glacial 

 till there is a tendency for soil to accumulate on the upper 

 beach and as this process proceeds many other species make 

 their appearance, such as : 



Equisctum arvense Ligusticum scothicum 



Elymus arenarius var. Coelopleurum actaeifolium 



villosus Scutellaria galericidata 



Urtica dioica Galium Aparine 



Rumex pallidas Bid ens frond osa 



Rumex Acetosella Cirsium arvense 



CaJcile edentula 



The upper beach is never very extensive and it may be 

 entirely lacking. Often there is a sharp transition to a 

 brackish pond or marsh and again to an upland forest. In 

 some instances the forest has encroached upon the shingle, 

 but it never forms a distinctive covering. 



Association-types of gravelly and sandy beaches 

 In the more protected reentrants along the shore, gravel 

 and sand beaches are formed. The pitch of these beaches 

 is much less sharp than in the case of shingle beaches and 

 often they are nearly level and so extend for considerable 

 distances seaward. Almost invariably they are composed 

 of coarse gravel or fine pebbles, save near the upper edge 



