72 



SANTORIN. 



[Ch. XXVII. 



CH' 



whole mass of Santorin stood at a liiglier level by 1,200 feet 

 tliat this single ravine or narrow valley now formino« ' the 

 northern entrance/ was the passage by Avhich the sea entered 

 a circular bay. 



But at a still earlier period when the ancient volcanic 

 cone, of wliicli tlie outer islands are the remains was still 

 more elevated above the level of the sea, there may have 

 been a deep valley of subaerial erosion cut by the principal 

 river which then drained Santorin, which may have con- 

 sisted of one lofty volcanic cone afterwards truncated by a 

 paroxsymal explosion such as we have already spoken of in 

 the case of Galongoon, p. 57, and when treating of the sup- 

 posed origin of the Val del Bove on Etna. It would then be 

 necessary to imagine the subsidence and partial submero-ence 

 of this original island in order to explain the present gulf and 



the deep channel (B, fi 

 gorge of fluviatile erosion. 



g- 



95) 



coinciding with the ancient 



All the outer islands Thera, Therasia, and Aspronisi are 

 covered with one great uniform mass of volcanic matter, 

 exxjressed by d, d', in the section fig. 9G, p. m. This great 

 overlying deposit has been called pumiceous by many ob- 



M 



ments 



Such a mass may w^ell be imagined to be the product of that 

 paroxysmal eruption by which so large a part of the great 

 cone was destroyed, and the gulf formed, in the middle of 

 which the Kaimenis have since been thrown up. 



Thera, Therasia, and Aspronisi are exclusively composed 

 of volcanic matter, except the southern part of Thera, where 

 Mount St. Elias {d d, fig. 97) reaches an elevation of 1,887 

 feet above the sea, or three times the height now attained by 

 the loftiest of the igneous rocks.* This mountain is formed 

 of granular limestone and argillaceous schist, and is much 

 more ancient than any part of the volcanic cone, one side of 

 the base of which now abuts against it. The inclination, 

 strike, a,nd fractures of the calcareous and argillaceous strata 

 of St. Elias have no relation to the great cone, but, according' 



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* Virk-t, Eull. de la Soc. G^ol. dc France, tome iii. p. 103. 



