1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 207 



time, no trace of organisms having been detected in the verrucano, 

 it is enough to repeat, that it vmderUes the fossiliferous hasso- 

 jurassic hmestones. The lowest masses in the deep gorges near 

 Stazzemma are the well-knoT\-n mottled "Bardiglio" and other 

 marbles. These are overlaid by schists with quartz veins, which 

 have been converted into dark slates having a true cleavage, and are 

 largely worked for use. The latter are covered by massive buttresses 

 of cavernous "rauch-kalk," in parts graduating into a black and 

 dark dolomite forming picturesque peaks. On the eastern side of 

 the range this massive buttress is irregularly overlapped by lighter- 

 coloured limestones with flints, possibly the representative of the 

 neocomian limestones, which in their turn throw off macigno and 

 other overlying rocks. In ascertaining that the crystalline marbles 

 of Carrara are really altered Jurassic rocks. Professor Pilla has shown, 

 that the dark-coloured fossiliferous limestone of the valley of the 

 Tecchia, which contains the same fossils as the marble of Porto Yenere, 

 can be followed until it graduates by a change of colour and crystal- 

 lization into the pure white marble of Carrara*. Professor Savi ad- 

 mits that the mineral masses exhibit the same general succession 

 in the Pietre Santine and Apuan Alps as in the Pisan hills f. Now 

 the latter, which I examined, are unquestionably for the most part 

 of Jurassic, or of what some geologists may call Jura-liassic age, as 

 proved by fossils. 



In the parallel of Carrara and to the north of that place, the white 

 marble rocks, forming regular strata, rise up with associated schists 

 into the lofty peaks of Altissimo, &c., and dipping to the W. and 

 N.N.W. form the eastern boundary of a great trough watered by 

 the Magra, the centre of which, occupied by tertiary and alluvial 

 accumulations (Caniparolo and Sarzana), is flanked on either side by 

 low hills of macigno, the strata of which repose, on the east, upon the 

 limestones of the Apuan Alps, and on the west, upon the calcareous 

 promontory that forms the eastern side of the gulf of La Spezia. 



When this promontory is surveyed in the coast cliffs between the 

 headland of Ponte Corvo near the mouth of the Magra and the 

 town of La Spezia, it is seen to be made up, on a miniature scale, of 

 nearly all the varieties of limestone, schist, breccia, rauch-kalk and 

 marble, which constitute the lofty parallel chain of the Apuan Alps. 

 I made a detailed examination of all the strata from the south of 

 Capo Corvo, by Porto Telaro to the old fort of St. Bartolommeo, 

 and found that there was there the same ascending order as in the 

 Apuan Alps, and I was therefore convinced that it was simply a less 

 elevated parallel fold of similar rock-masses (fig. 32). The lower 

 strata are grey, calcareous schists, courses of scaly limestone, in parts 

 highly altered, overlapped by a strong band of white, thick-bedded, 

 impure, statuary marble, with a schistose lamination. This passes 

 up into a concretionary, mottled, purple and white limestone, large 

 calcareous geodes being arranged in the lamin?e of deposit in a base 

 of glossy purple and green schist. This calcareous group (1) is 



* Bull. Soc. Geol. de France, 1847, vol. iv. p. 10G9. 



t Considerazioni suUa struttura geologica delle Montague Pietre Santine, dal 

 Prof. Cav. Paolo Savi: Pisa, 1847. 



