306 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



they were void of fossils, the enormous accumulations of finely-lami- 

 nated beds, which overlie the true equivalents of the chalk, and are 

 followed by the deposits which hitherto have alone been viewed as 

 younger tertiary, must represent so long a period, that as physical 

 monuments only they are in my mind's eye, full and complete equiva- 

 lents in time of the eocene of geologists * . 



And now a word upon the reform which the adoption of this view 

 must introduce into geological maps. The truth is, that in previous 

 classifications of the rocks of Southern Europe the eocene formation 

 has been almost omitted, chiefly because it there usually forms the 

 upper portion of a continuous and unbroken series of strata, of which 

 the neocomian limestone or lowest member of the cretaceous system 

 is the base. In some tracts it will doubtless be difficult, except the 

 scale of the map be large, to indicate the separation of the eocene 

 from such cretaceous rocks ; but on the other hand, it will be as easy 

 as it is necessary to mark this formation by a distinct colour over 

 enormous spaces, separating it from the cretaceous on the one hand 

 and from the younger tertiary deposits on the other. Even in the 

 most general maps I conceive that this distinction may be effected. 

 No geological division can, indeed, be more essential than that which 

 distinguishes lower tertiary rock-masses from those of upper secon- 

 dary age ; inasmuch as, with the exception of certain beds of junction, 

 the two groups have no organic remains in common, and afford the 

 clearest proofs of having been formed at different periods of time, 

 and when the submarine fauna underwent a total change. 



Lastly, let me say, that without taking a comprehensive view of the 

 whole question, and alluding to the works of my contemporaries, I 

 should not have made apparent the value of the establishment of a 

 clear order of secondary and tertiary succession in the Alps, Carpa- 

 thians and Italy. In respect to my leading object, I repeat, that 

 wherever true and full representatives of the different members of 

 the cretaceous system occur, from the neocomian or equivalent of the 



* In a letter recently received from M. Alcide d'Orbigny, he thus expresses him- 

 self : " For three years I have made the most extensive researches upon Nummu- 

 lites ; and in comparing all the stratigraphical and palaeontological results, it is im- 

 possible not to recognize therein tv^^o distinct epochs, as represented by strata, super- 

 posed the one to the other, and having each its proper fauna. One of these epochs, 

 which I have recognized in the French Alps, the Pyrenees and the Gironde, cor- 

 responds to the plastic clay of Paris and London, and which, belonging to the 

 lovs^er sands of Soissons, I have named * Etage Suessonien ' ; the other, equally 

 common in the Alps and the basins of the Gironde, and which includes the * cal- 

 caire grossier ^ of Paris up to the gypsum of Montmartre and the London clay, &c., 

 I designate ' Etage Parisien.' These divisions, based upon a considerable number 

 of facts, are detailed in the work I am now printing, and the entire composition of 

 their characteristic faunas is given in my * Prodromus of Universal Palaeontology.' 

 The habit I have acquired of determining these fossils makes me regret that I can- 

 not go to inspect your collections in London ; but the portions of them I have 

 seen in the hands of our friend M. de Verneuil have led me to recognize at once 

 what I was already acquainted with in the Pyrenees and the French Alps. Again, 

 the fossils I have examined in the collection of M. TchihatchefF (recently brought 

 from Asia Minor) confirm me in my opinion, and would lead me to extend the limits 

 of these tertiary stages, as you have suggested, even to Hindostan." 



