THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. 



m. II.— FEBEUARY, 1874. 



I, — On the Origin of the Lagoon called The Fleet, 



Dorsetshire. 



By G. H. KiNAHAN, M.R.I.A., etc., etc. 



IN the November Number of this Magazine (VoL X. p. 481) the 

 Eev. 0. Fisher has called attention to the formation of the Fleet, 

 Dorsetshire, and puts forward suggestions as to its formation in 

 opposition to the sub-aerial denudation theory of Messrs. Bristow 

 and Whitaker. To me the formations of the Fleet and Chesil Beach 

 seem easily explained, as similar beaches are not uncommon on 

 other parts of the English coast, and also on that of Ireland ; but 

 inland behind many of these banks the spaces that were formerly 

 lagoons are now reclaimed land. 



Tidal currents running parallel or nearly so to a coast-line, denude 

 it evenly if all the rocks forming the coast-line are of similar 

 hardness and resist its action equally. If, however, there are very 

 soft or very hard portions, the former are denuded out to form guts 

 or bays, while the latter are the nuclei of capes, points, and heads. 

 When two headlands begin to form on, say, an east coast with the 

 set of the incoming tide or principal current from south to north, at 

 first there will be a long gradual curve formed between them, but 

 eventually the current sweeping round the southern headland will 

 denude the land rapidly on the N.E. of it, forming the south 



Diagrammatic Sketcli of part of Wexford Coast. 



portion of the bay between the heads into an abrupt curve ; while 

 from the chart of the coast we learn that shoals {a a a and b) have 

 •accumulated between the headlands, due to the meeting of the 



DECADE II. — VOL. I. — NO. II. 4 



