the Western Part of Asia Minor. 35 



if we suppose the latter to have been submerged beneath a body of water, either at 

 the time of their ejection or subsequently, the explanation will be more easy. The 

 action of water would soon obliterate all the sharp features of these mounds of 

 ashes, and by filling up the cavities in the lava-streams with transported matter, 

 would form that smooth and fertile surface which they now present. It is true 

 that this explanation is not without its difficulties. The lake which existed here, 

 before the basalt of the first period was poured forth, had long been drained, and 

 deep valleys of denudation had been excavated in its bed, before the second period 

 of volcanic eruption commenced. In order that the valley might be reoccupied 

 with water to a sufficient elevation to cover the tops of the volcanic cones, the 

 gorge at Adala would require to be blocked up to a height of perhaps 2000 feet, 

 and the sojourn of this supposed mass of water must have been very transient, as 

 we find no regular sedimentary deposits of any importance which can be assigned 

 to it. Such a supposition involves an extensive flight into the region of conjecture, 

 and many geologists would probably prefer explaining the wasted condition of 

 these volcanic mounds, by means of ordinary atmospheric causes acting through 

 an immense period of time*. 



We have before alluded to the singular fact, that all the cones of the second period 

 rise out of the ridge of schist and marble on the south of Koola, and its three lateral 

 offsets (p. 29) ; while the three volcanos of more recent date occur in the plains which 

 intervene between the several ridges (p. 31). This phsenomenon may perhaps be 

 accounted for by supposing, that several cracks and fissures were produced in the 

 schistose ridges at the time of their elevation, through which the igneous products 

 at first found vent ; that in process of time, lavas having been injected into all the 

 fissures and become cooled, the whole mass was rendered more compact than it was 

 before ; and therefore that when, at a later period, volcanic forces were again in 

 action, the points of least resistance would be in the plains which intervened 

 between the consolidated ridges, where the new eruptions would consequently take 

 place. 



It may be doubted whether the older series of eruptions supplied the forces 

 which elevated the ridges themselves. The stratification of the latter is very 

 irregular, and seems not to possess an anticlinal arrangement. Moreover, the un- 

 disturbed horizontality of the lacustrine beds in the vicinity, is scarcely compatible 

 with any great subsequent disturbance of the schistose rocks. 



* It may assist conjecture as to the relative and perhaps also the absolute antiquity of the three sets 

 of volcanic eruptions above mentioned, if we remind the reader that the valleys have been denuded to 

 tJie depth of 800 feet since ihe first period of eruption, of 200 feet since the second, and 80 feet since 

 the third. The different density of the materials acted on in each case must of course be taken into 

 the account. 



F 2 



