550 George Maw — Notes on the Mediterranean. 



ration bore a larger proportion to the land area of supply than does 

 the open ocean to its sources of accession from land drainage, which 

 is not the case. The evidences of rejoeated recent changes of level 

 in the Mediterranean basin seem to suggest a more satisfactory 

 explanation, viz, : That the influx through the Straits may be due 

 to a gradual depression of the bottom now going on. The area of the 

 Mediterranean is so great compared with the width of the Straits, 

 that an amount of submergence, too slight to be perceptible on the 

 boundary of the area subject to it, might produce such a current as 

 exists, through the connecting channel with the Atlantic. 



3rd. Limestone Caverns and Submarine Springs on the Coast-line. — 

 To the east of Mentone the Oolitic Limestone is extensively honey- 

 combed with cavernous channels, some of which are filled up with 

 loamy earth ; others are open ; and some serve as channels for sub- 

 terranean streams. These caverns, which without doubt had a sub- 

 aerial origin, are now, in one place at least, prolonged to a consider- 

 able distance below the present sea-margin. At about a mile to the 

 east of Mentone, just opposite the point where the limestone is seen 

 to be perforated with caves and channels, a fresh- water spring bursts 

 up to the surface with sufficient strength to produce in calm weather 

 a little oasis in the salt water. This spring probably at one time 

 debouched on and flowed over dry land, since which the coast must 

 have been considerably submerged. 



EVIDENCES OF UPHEAVAL. 



4th. Lagoons on the Coast. — The brackish water lakes which 

 extend from the Spanish frontier on the west to the delta of the 

 Ehone, and also along the east coast of Corsica, present some features 

 indicating an upheaval of the coast. They are entirely distinct in 

 character from the Etang de Berre, the salt-water lake near Mar- 

 seilles before referred to. They are bounded by narrow spits of low 

 land running parallel with the general direction of the coast, and 

 these, cutting off, as rt were, the indentations of the higher ground, 

 give to the coast on the map between Perpignan and Marseilles a 

 more direct line than the higher ground actually follows. These 

 indentations are occupied by low marshy ground of an average 

 height of eight or ten feet above the sea-level, and the shallow 

 lagoons are shut off from the sea by bar-like ridges of shingle, 

 blown sand, and marshy meadows. There is little in the character 

 of these flats on the French continental coast to distinguish them 

 from the seaward extension of low ground seen at the mouths of 

 many rivers, and which accumulate independently of oscillations of 

 level ; but the lagoons and flats on the east coast of Corsica of pre- 

 cisely similar character and height afford evidence of a rise of the 

 coast of at least 25 feet since the neighbouring low ground was 

 deposited. 



The most northerly of these is the Stagno di Biguglia, 3J miles 

 south of Bastia. It is a long narrow pool of brackish water, several 

 thousand acres in extent, on the sea-margin of a great level tract of 



