1871.] JTJDD PTJNPIELD FORMATION. 225 



by insensible gradations, and contain a considerable number of 

 fossils in common. 



The lowest of these consists of alternations of limestones, sand- 

 stones, and marls, yielding a large series of fossils, by means of which 

 it is referred without doubt to the Urgonien. Its thickness is about 

 500 feet ; and it rests indifferently (the Lower Neocomian being 

 absent) on all the older rocks. In the Utrillas basin this division 

 contains only jet, but in other districts it furnishes beds of coal. It 

 is in these that the mines of Santa Barbara and la Fuen Gargallo 

 are worked. 



The second series, consisting of ferruginous sandstones and lime- 

 stones alternating with sandy clays, is that which contains the 

 same fossils as the Marine Band of Punfield. These beds, although 

 their fauna presents some peculiarities, are doubtless to be referred 

 to the highest portion of the Middle Neocomian. At Utrillas, where 

 they attain a thickness of 530 feet, they contain ten beds of coal, 

 lignite, or jet, which are extensively worked. It is these beds which 

 constitute the Calcaire a Trigonies of M. de Verneuil, The faima 

 of these beds seems to be especially characterized by the presence in 

 great abundance of Gasteropods of a new genus, which has already 

 unfortunately received four names (Cerithiimi, Omphalia, Cassiope, 

 and Vicarya). No less than six species of this genus have been 

 described from Utrillas, three of which occur at Punfield, and one 

 of them in the " Rhodanien " of Switzerland. It is remarkable that 

 there is scarcely a single fossil found in the Marine bed of Punfield 

 which does not also occur in these Spanish beds. 



The third and highest of these series of Spanish rocks consists of 

 variegated and mottled clays and sands of bright colours (crimson, 

 grey, green, violet, and white), which greatly resemble the Keuper, 

 and were, indeed, long mistaken for it. They are probably in great 

 part of freshwater origin, though a few marine shells have been 

 found in them, which enable us to refer the series to the Upper 

 Neocomian. Their lower portion consists of dark-coloured clays 

 with a pyritous combustible mineral, formerly used for the manu- 

 facture of alum. This series, which is 600 feet thick, contains beds 

 of lignite, which are worked in many places. It is overlain by strata 

 representing the Gault and other members of the Cretaceous. 



These coal-basins of Eastern Spain have been estimated as being 

 capable of supplying the whole of the peninsula for more than 200 

 years. 



VIII. Conclusion. 



The grounds on which I have ventured to suggest that the strata, 

 the nature and relations of which I have endeavoured to illustrate 

 in the preceding pages, are worthy to rank as an independent for- 

 mation* are as follows : — 



* The term "formation" is unfortunately employed by English geologists 

 with two very different significations — either to indicate great groups of strata 

 like the "Silurian" or "Jurassic," or for smaller divisions, like the "Ludlow 

 series," or the "Great Oolite." It is with the latter meaning only I have 



