Sonthem Flank of the Tyrolese Alps near Bassano. 283 



apennine* ; and thus formations of the age of our London clay 

 being confounded .with those blue marls containing a variety 

 of recent shells, it now becomes quite essential to state that the 

 inferior members are essentially different from the superior in 

 zoological contents ; it being in the upper beds only that we find 

 a large proportion of shells of the present sea. To this latter 

 epoch belong the conglomerate sands and marls of Asolo and 

 Bassano; and the strata which succeed, offer (amidst the 

 few specimens which my' hurried examination permitted me 

 to collect), some species resembling those of the Bourdeaux 

 basin ; whilsthy far the greater number of the shells enumerated 

 in the oldest members of marl and limestone, near Possagno 

 and on the Brnnr.n, aro identical in species with those of the 

 Calcaire grossier of Paris, and the London clay. The lowest 

 beds of this formation both in the north of Europe and in Italy 

 are very similar in containing not only many of the same spe- 

 cies of mollusca, but also identical species of nummulites, ca- 

 ryophyllia, &c Nor can it be urged that the multilobular 

 fossils of these inferior strata are also found in the higher 

 tertiary deposits of Italy, for the microscopic shells of Sienna 

 figured by Soldani differ entirely from those of the Calcaire 

 grossier both in family and species.' 



Now although we may compare the nummulite rock of Bas- 

 sano with the Calcaire grossier of the London and Paris basins, 

 we cannot extend the comparison to the subjacent strata : for 

 unlike certain parts of the Paris basin, where a formation dis- 

 tinguished by its freshwater and terrestrial remains is inter- 

 posed between the Calcaire grossier and the chalk, the plastic 

 clay is, entirely wanting near Bassano, and there also the 

 representative of the Calcaire grossier is in conformable appo- 

 sition to the scaglia or rock containing ammonitest: so that 

 ■in this portion of the earth's crust we have no trace of any 

 interval of repose bfetween the secondary and tertiary epochs 

 when, as some geologists have imagined, the ocean subsided, 

 and the land wa3 left dry for terrestrial and fresh- water pro- 

 ductions to accumulate on its surface ; — on the contrary, Ave 

 here find a continuity of marine deposits or conformable pas- 

 sage from the rocks called tertiary to those named secondary, 



* Conch i oh f/ia Subapenaina, vol. i. p. 97. 



t It may be remarked, that the plastic clay is not only absent in the 

 north of Italy but also in most parts of England, and in some situations 

 in Fiance, provided that formation is to be defined as one of fresli-u-ater 

 origin. In the Isle of Wght, and at Reading-, it is well known that the 

 lowest tertiary beds are exclusively charged with marine exuviae. If zoo- 

 logical evidence therefore, be considered decisive, the plastic clay cannot 

 be- viewed as a distinct and extensive formation resulting- from any general 

 cause, Itul rather as an accidental a-stuary deposit, produced by local cir- 

 cumstances. 



