75^ PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 18, 



some evidences of this are seen in detached portions of the newer 

 gravel beds, reposing horizontally upon highly-inclined strata of the 

 lacustrine group. It is thus difficult to determine the precise age of 

 these gravels, or how nearly or distantly they may be allied to the 

 deposits of undoubted freshwater origin. The coincidence of their 

 character and conditions in the three described and distant localities 

 of Samos, Koumi and Oropo, denotes the contemporaneous origin of 

 all the gravelly deposits. They may perhaps be referred to that 

 volcanic period when so many eruptions of igneous matter burst 

 over the bed of the lake, to a great extent on the Asiatic coast, and 

 particularly in the Gulf of Smyrna ; elevating some portions several 

 hundred feet, and doubtless submerging others to as great an 

 amount. 



The addition of these three localities, with freshwater formations 

 apparently identical with those on the Asiatic shore near Smyrna, 

 render it more difficult than ever to define the boundary of this 

 ancient lake ; and this is particularly the case with regard to that of 

 Samos, as it before appeared probable that this basin was confined 

 to the northern part of the JEgesm Sea. Having now passed that 

 supposed boundary formed by the belt of islands extending from 

 Eubcea to Samos, which renders it probable that the lacustrine de- 

 posits of Rhodes, Cos and Cerigo are of the same age, and having 

 found the formation also in Greece, where it is perhaps important 

 to remark that the fresJfwater strata above Markopoulo are 200 or 

 300 feet higher than the valley which crosses by Thebes from the 

 Eubceic Channel to the Gulf of Lepanto or Corinth, we have no de- 

 fined boundary for circumscribing the limits of this lake, which must 

 have been of considerable extent. The question seems to be in- 

 volved, whether it was a local basin confined to the eastern division 

 of the Mediterranean, or whether it did not rather extend over the 

 whole of it, connecting the Levantine with these eocene freshwater 

 deposits on its border, in the low countries of Provence and Lom- 

 bardy (and probably also with the freshwater limestone recently 

 found by Mr. Hamilton on a branch of the Arno). These we may 

 suppose were all of them elevated portions of the bed of this great 

 lake, near each of which igneous eruptions of contemporaneous age 

 have taken place. 



Knowing the error which may arise in drawing conclusions from 

 the present configuration of the country, and particularly in a district 

 which has so frequently, in all its parts and in all geological ages, 

 been subject to great volcanic disturbances, the extent and amount of 

 which we have no means of ascertaining in that part covered by the 

 sea, the view thus suggested will require the introduction of fewer 

 hypothetical disturbances in order to connect, as parts of the bottom 

 of one great lake occupying the whole of the Mediterranean basin, 

 the several localities in which eocene lacustrine deposits occur, than 

 that which would make each a separate lake of limited extent. 



There is another point of considerable geological importance con- 

 nected with this supposition, which also it tends materially to 

 strengthen, viz. the total absence of any eocene marine formation 



