396 H. E. Strickland, Esq., on the Geology 



of the lake had been drained by the igneous eruption ; and streams flowing 

 from all sides would carry to this point the pebbles which, during the quiescent 

 state of the lake, formed a shingle beach around its margin. In course of time 

 the denudation of the outlet would complete the work of desiccation, and the 

 whole drainage, of what is now the Plain of Sedikeui, would reach the sea by 

 the ravine at present traversed by the Meles. That all these operations have 

 taken place, will, I think, be evident to any one, who will make a careful 

 survey of the locality. 



The stratification of the lacustrine series is, in general, nearly horizontal ; 

 some local exceptions, however, exist in the vicinity of the igneous rocks. 



4. Trachytic rocks. 



The greater part of the lacustrine series had been deposited, when the basin 

 of Smyrna became the seat of volcanic action ; and an enormous mass of tra- 

 chytic matter was poured forth, and spread over the bed of the lake. The 

 eruption appears to have ceased as suddenly as it began, for there are no al- 

 ternations of trachytic and lacustrine rocks, — no injection of dykes, or other 

 phaenomena, which indicate a long continuance of igneous action. 



These rocks occupy a surface of about five miles by two, and a reddish- 

 brown, porphyritic variety prevails throughout nearly the whole area. A 

 remarkable feature in the trachyte is the close approach, which it occasionally 

 makes to a stratified structure. It splits into slabs from a foot to an inch in 

 thickness, and their cross section exhibits stripes of various colours, parallel to 

 the planes of cleavage. These strata (if they may be so called) are in some 

 places accumulated to the thickness of one hundred feet, and are traceable 

 laterally for as many yards. This is especially the case on the hills about two 

 miles west of Smyrna. The crystalline texture of this stratified trachyte de- 

 cidedly indicates igneous fusion, and the explanation of this peculiar structure 

 is, therefore, by no means easy. It may, however, be conjectured, that when 

 the fluid trachyte expanded horizontally from the point of eruption, any vari- 

 ations of substance or texture would be drawn out and extended in planes 

 parallel to the horizon, and when cooled would cause coloured stripes and 

 fissures in the rock, in the direction of those planes. It must, however, be 

 observed that the apparent strata are now far removed from the horizontal 

 position, supposing them to have once occupied it. 



These trachytic rocks are, in general, homogeneous, but in some places, 

 they contain numerous angular blocks and fragments of black porphyritic 

 trachyte, much harder than the reddish paste in which they are imbedded. 

 This species of conglomerate is well developed, about 2 miles west of Smyrna, 

 in a ravine near the sea. 



On the north side the trachytic rocks descend to the shore, but along their 



