212 Sir R. I. Miirchison on the Geological Slmcture 



Admirably exposed on the flanks of the Venetian Alps, and 

 scarcely less so at Nice, the cretaceous system in all its members 

 (from the Neocomian limestones of foreign geologists or equivalents 

 of the English lowest greensand up to the white chalk inclusive) is 

 surmounted by nummulitic eocene deposits, which near Asolo and 

 Bassano are followed by miocene and pliocene shelly strata. After 

 showing how they occupy a trough between such Alps and the Eu- 

 ganaeans, the author explains how the latter hills have recently been 

 described by M. de Zigno as composed of Oxfordian Jura and a 

 full cretaceous system up to the white chalk inclusive, overlaid by 

 the nummulitic group. In Liguria, Modena, Lucca and Tuscany, 

 such clear evidences do not exist ; for there the formations above 

 the Oxfordian Jura are singularly devoid of fossils, and the series 

 between that horizon and the deposits of miocene age, with the ex- 

 ception of certain flaggy limestones (Alberese), assumes an arena- 

 ceous type. At very rare intervals only, and chiefly to the south of 

 Florence, are any bands of nuramulites observable ; but where they 

 occur the author refers all the " macigno " sandstone which is asso- 

 ciated with or overlies them to the eocene epoch ; such rocks being 

 perfectly undistinguishable from the " macigno Alpin," or flysch of 

 the Alps. As, however, these rocks repose upon others, including 

 vast thicknesses of the Alberese limestone, so largely seen in the 

 Apennines between Bologna and Florence and in the northern part 

 of the Tuscan Maremma, it is presumed that much of the latter mat/ 

 represent the chalk. For although these rocks contain fucoids, one 

 or more of them being said to be similar in species to those which 

 overlie the nummulite strata of the Alps, no sort of reliance can be 

 placed on the presence of such marine vegetables, which in the Alps 

 range from the lower chalk high into the eocene ; whilst in Tuscany 

 an ammonite and a hamite have actually been found in these infra- 

 nummulitic masses. The inference of the author is, that Prof. Savi, 

 though correct in viewing a portion of this series as cretaceous, has 

 erred in including it in the nummulitic rocks. 



In paying a just tribute to the talents, labours and character of 

 the lamented Prof. Pilla, the author avows the impossibility of ad- 

 mitting his term of " Systema Etruriano '"' as an equivalent for any 

 true geological division, as in it are comprehended strata which that 

 ■writer had admitted to be cretaceous, with others which it is the 

 chief object of this memoir to establish as lower tertiary. 



In passing into the Papal States and Naples, the superposition 

 of the nummulitic limestones with their usually associated fossils 

 to hippuritic limestones, the equivalents of the chalk, is seen to be 

 resumed ; and thus the same general succession as in the Alps and 

 Carpathians is maintained. Cases illustrative of this order, with 

 much overlying macigno, are pointed out in the Sabine Hills and 

 in the kingdom of Naples. 



A transverse section of the Monferrato Hills (Superga) near Turin 

 exposes a most instructive tertiary succession. A coralline concre- 

 tionary limestone with small nummulites (Gassino), though de- 

 scribed and mapped as cretaceous by CoUegno and others, is shown 



