4S Geographical CoUections. 



the ingenious observations of M. Elie de Beaumont, by determining their epoch 

 in the chronology of formations. 



The island of ^gina which, in a small space, presents nearly all the forma- 

 tions of the continent, and, moreover, volcanic deposits, has appeared to me to 

 merit a very particular examination, and I have traversed it in all directions. 



In the plutonic revolutions which they have undergone, at least three very 

 distinct epochs are recognized. The most recent has probably taken place within 

 the period of historic records, and was contemporaneous with the eruption of the 

 volcano of 3Iethana. Its effects are limited to numerous fractures. 



The second took place at tlie middle of the tertiary period, between the depo- 

 sition of the clays, and that of the coarse limestone. There may be mentioned 

 among its products, at the centre of tlie island, a small dome of trachytic conglo- 

 merates, evidently formed by upraising ; and, in the low parts, numerous beds of 

 trachytic sands and conglomerates, with limestone cement, existing in the heart 

 of the tertiary formation. 



Trachytes, porphyries, and leucostines, form a vast expanded deposit, which 

 extends as far as tlie peninsula of Methana, and the island of Poros, and charac^ 

 terizes a third epoch. 



We discovered in Magna, in the midst of the small chain of Lyco-Vouno, the 

 deposit of the antique green porphyry or ophite, employed in the decoration of alj 

 the temples of the Morea. It belongs to the porphyries of the coal formation. 



The compact limestone contains as subordinate beds white granular limestones, 

 red and green marbles, ophicali, and cipoline limestones. This fact, which I 

 should not have imagined, is well proved. May this also be the case with tlie 

 Parian and Pentellic marbles ? After many fruitless inquiries, I have succeeded 

 in finding a few fossils in this formation. They will be useful to decide the 

 place or age which ought to be assigned to them ; a question so much the more 

 difficult, as enormous vacuities exist here in the succession of tlie formations. 



The upper sedimentary deposit extends over the whole shore district, and, 

 perhaps, stretches pretty far into the large and deep valleys of the Pamisus, the 

 Alphaeus and the Eurotas. It has formed the isthmus of Corinth, and the rich 

 plains of the Elide, and formerly filled up the gulf of Athens, in which it has 

 left on all the islands, shreds which attest its existence and its destruction. 



Its simplicity is such, that its study presents few difliiculties. It contains, in 

 some parts, numerous fossils in a fine state of preservation. 



The observation of limestone beds, in their regular position, perforated at dif- 

 ferent heights with numerous cavities formed by boring shells, seems to give coun- 

 tenance to the opinion of a gradual retreat of the waters. 



I am examining the present deposits of the shore districts, as being intimately 

 connected with those which have preceded them, and as being calculated to throw 

 much light upon the phenomena of this epoch which is still so obscure. 



The examination of the action of the seas upon its shores, and particularly on 

 the compact limestone, has led me to discover a compact substance which appears 

 to me new. It is of a brown colour, mammillated, hard, compact, and always 

 occupies the upper limit of the wave at tlie surface of the limestone. 



The decomposition of the rocks in the monuments of different ages, the alluvia 

 whicli have swallowed up temples to the level of their capitals, and especially 

 conglomerates, having all tlie hardness of the oldest rockjjj and containing tiles 

 and fragments of pottery, shew that the works of men at length acquire a place in 

 the materials of the globe which we inhabit, and enter into the domain of geog- 

 nosy. 



I hope that before leaving Greece I shall be able to visit the Archipelago, in 

 whicli case I shall have the honour of communicating to you the new observa- 

 tions which I make there. My materials are as yet in a scattered state, and it is 

 only in Paris that I should be able to arrange them. I should be happy were I 

 to receive your advice, and to be enlightened, with reference to my own investiga- 

 tions, by those new and profound views which you give out in all your works. 



