1912-13. J 66l 



Almost equally remarkable is the persistence of the very low 

 ridges in the interior of the tract. One, for example, near 

 Bellarena Station, only about 3 feet higher than the adjoining 

 hollows, and some 40 yards wide, is distinctly traceable for a 

 distance of about a mile. 



The trend of the ridges varies gradually from south-east and 

 north-west to nearly east and west at Bellarena, swinging a little 

 to the north of east near the high ground of Benevenagh and 

 Magilligan Station. These directions may probably be explained 

 on the assumption that the prevailing high winds from the north- 

 west operated upon unlimited quantities of sand, the directions 

 near the ground changing into conformity to that of the mountain 

 foot, as the winds approached it. 



It may be asked how are we to account for so much sand, 

 when the present beaches laid dry at ebb-tides are of compara- 

 tively limited aggregate area ; and the beach within is not such as 

 to yield blown sand ? 



To account for it we may note the following data, viz. : — 

 (1.) — A portion of the great blown-sand tract occurs in Carrow- 

 menagh, about one half to one mile south-west of the Roe Bridge, 

 separated from Magilligan by the water and alluvial flat of the 

 river. (2.) — It rests upon the main raised beach which is there 

 some eight feet above the high tide level, and is cut into by the 

 sea which formed the two successive shelves, lower than the main 

 raised beach. (3.)— The blown sands therefore began to collect 

 when the sea had so far receded as to leave the tract at Carrow- 

 menagh free of water. Freshly exposed sand-beaches existed 

 inside and outside Lough Foyle, at that stage of land-rise. (4.) — 

 For each of the three discernable land-rises there was denudation 

 of the older beaches, washings of the sands, and deposition of 

 easily moved material on three corresponding foreshores. That 

 is to say, there were foreshores exposed at four successive periods, 

 each probably as large as the present foreshore, and not, like that 



G 



