Maw — On Watersheds. 



347 



form tliat would be expected from the sea running up among the 

 gentle undulations of the watershed valleys. The sinuous line 

 of the inner margin of the reef also forms a striking contrast to the 

 comparatively straight margin of the exposed outer coast. 



Aiother question that invites consideration is, that if marine 

 denudation has determined the final contour of the land, how is it 

 that erosion should have continued up the land-locked arms of the 

 sea intersecting the submerged mountain chains, whilst the protecting 

 flanks, exposed to the full force of the sea, remain? Unequal hard- 

 ness and resistance will scarcely account for it, as the direction of 

 the valley is not related to the structure of the rock. A map of the 



\ '^7« 



A Coast Line, the Result of Submergence. Port Boyal, Jamaica. 



(Scale : 1 inch to a mile.) 



The Coast connecting A\.o B takes a circuit of about 30 miles enclosing Kingston Harbour. 



Snowdon district of the Italian Alps, or of a mountainous island like 

 Jamaica, will, at a glance, exhibit the kind of outline with which 

 the sea would surround a mountain chain at almost any zone of 

 submergence : a large proportion of the water would be entirely 

 land-locked, and the deep bays, where it must be assumed marine 

 denudation continued with activity, would be protected from the active 

 fury of the ocean. 



No one will dispute that many parts of the land represent cliffs 

 and coasts eroded by the sea ; but these appear to be altogether 

 subordinate to the watershed system, and do not, as a rule, harmonize 

 with its outlmes. The sea, in its trenchant action on the coast, 

 may have done a greater work of erosion than subaerial denudation, 

 but the two are inharmonious in their operations : the sea works 



