118 0;i the Cause of the Earthquakes in the Ionian Isles* 



** The streams are constant throughout the year, except when 

 the mouths of their channels get accidentally choked up with 

 sea-weed, which collects in large quantities in the harbour of 

 Angostolk 



" On commencing their descent no sound is observable, but 

 through the apertures which open into the excavation made by 

 Mr Stephens, numerous bubbles of foetid air are at times disen- 

 gaged. This fact has but lately been observed, and takes place 

 only when the quantity of water escaping is small. 



** Mr Stephens has been present at his trench when sharp 

 strokes of earthquakes have occurred, but did not observe any 

 particular effect or changes result therefrom." 



Thus far Dr White. I may add from my recollection of the 

 locality, that where the streams descend, the shore is low, and 

 composed chiefly of calcareous freestone of very recent forma- 

 tion, hollowed into caverns here and there by the action of the 

 waves. 



Reflecting on the nature of the currents described by Dr 

 White, it is hardly possible to refrain from speculation; and, 

 indeed, it is in connection with their theoretical bearing that they 

 are chiefly interesting. 



In two points of view they appear particularly important, and 

 may be deserving of especial consideration. The first is in con- 

 nection with the theory of the formation of beds of mineral salt ; 

 the second with that of the production of earthquakes. 



I would wish at the present time to call the attention of the 

 Class chiefly to the latter, hoping that some of the able inqui- 

 rers who compose it, may follow up the subject, and investigate 

 it experimentally. 



My idea is, that the earthquakes to which Cephalonia, in com- 

 mon with most of the Ionian Islands, is so very subject, may be 

 owing to the descent of water into the earth, in situations where 

 there are great beds of clay or marl beneath the earth's surface, 

 and between porous and fissured strata, such as of freestone, al- 

 lowing of the ready access of this fluid. I am disposed to be- 

 lieve that clay or marl in absorbing water expands, and conse- 

 quently in drying contracts in all its dimensions. The few ex- 

 periments I have made with a coarse apparatus, the best I could 

 procure in Malta, were in favour of the conclusion. I may men- 

 tion one of them. Small cylindrical masses of calcareous marl, 



