Professor Hoffmann on the Geology ofMassa Carrara. 123 



well characterized ; but as to its mineralogical constitution, there 

 can hardly be a doubt, as not far from Ajola it occurs, alterna- 

 ting with the limestone in regular layers of from one to three 

 inches in thickness. In the larger portions of the felspar, iron- 

 pyrites occurs frequently, and also ironstone in veins. In the 

 neighbourhood of these substances, the limestone never alters its 

 texture, and invariably preserves its regular stratification. The 

 Macigno formation, which nearly surrounds the Apuanian Alp, 

 is a grey sandstone, which constitutes nearly the whole of the 

 northern half of the chain of the Apennines, and which has 

 hitherto been considered a greywacke. Numerous limestones, 

 divisible into groups, are subordinate to this sandstone. These 

 prevail chiefly round the Apuanian Alp, far above the sandstone 

 and its alternating slaty marls. The zone at the south-western 

 edge only, from Fosdinovo to Massa^ is entirely sandstone. The 

 remains of Fuci (especially the F. intrkatus) are characteristic 

 of this rock, and also of the limestone and slaty marl. The 

 sandstone formation everywhere reposes on the limestone ; and 

 where the Macigno is connected with the limestone, the two 

 seem most intimately united. The great resemblance, and the 

 direct union of the Galestro, and the older limestones reposing 

 on the slate, and even the old mica and talc slates, prove this 

 fact in the most perfect manner. Where the jNIacigno formation 

 consists chiefly of limestone, it is often hardly possible to assign 

 with precision the boundary of the two formations ; for their dip 

 is always the same, and the external resemblance so great, that one 

 might reasonably consider them as formations passing the one 

 into the other. 



The Macigno formation, notwithstanding its enormous extent, 

 and the peculiar character of its component rocks, is a geognosti- 

 cal equivalent of the great formation of the north of Europe, 

 the Chalk and Greensand, Its relations in position hitherto 

 observed, are in favour of this view. In Sicily, where this for- 

 mation is displayed in all those peculiarities which distinguish it 

 throughout the whole of Italy, the author was often surprised 

 by the completeness through a great extent, of the uniform 

 transition to the tertiary series. It is also rendered more pro- 

 bable by the repetition of the same circumstance in very 

 numerous points on the Italian continent. The immediate 



