Dr. Du Riche Preller — The Carrara Marble District. 557 



The intervening Val d'Arni lies at an altitude of about 1,000 metres 

 at its upper and of 900 metres at its lower end between Altissimo and 

 Sumbra, where the Arni and Freddone torrents join and under the 

 name of Turrite Secca are deflected to the east as tributary of the 

 liiver Serchio. 



III. The Geological Structure. 



The flat, fork-like curves formed by the crest lines of the two series 

 also constitute the direction of the two great anticlinal folds of the 

 range, the intervening Val d'Arni being the corresponding syncline. 

 The two principal folds are not, however, simply uniform anticlines, 

 but are composed of a succession of anticlinal and synclinal flexures 

 which, beginning at the Yinca Pass north of Monte Sagro at the western 

 and at Monte Pisanino at the eastern end, converge and merge into each 

 other near Monte Altissimo and thence extend to the Stazzema end 

 of the range. The extraordinary multiplicity of these flexures renders 

 their co-ordination extremely difficult, the more so as in many of 

 them, notably in the eastern series, the stratigraphical sequence is 

 reversed, while, more especially at their junction near Monte Altissimo, 

 and also near Renara in the Massa division, the strata exhibit extra- 

 ordinary contortions which only long and patient study and sections 

 of minute detail can unravel. The sections given in Pigs. I to IY 

 represent some typical examples, Fig. I showing the normal anticline 

 of Monte Sagro, Pig. II a lower part of the same anticline, with the 

 complete stratigraphical sequence from Miseglia to the Betogli and 

 the Fantiseritti quarries above, viz. north-east of Carrara; Fig. Ill the 

 normal syncline of Monte Corchia in the' Stazzema, and Fig. IY the 

 totally reversed stratigraphical sequence of the contorted flexure of 

 Monte Ronchi in the Arni division, in the junction zone of the two 

 great folds. 



All the principal mountains exhibit flexures, more or less accentuated, 

 not only along the precipitous ridges of the crest lines and on the 

 denuded mountain-sides, but in the marble quarries, as well as in the 

 cuttings and tunnels of the Carrara Marble Railway, all of which thus 

 offer a multiplicity of revealing sections. In some isolated cases, 

 where the visible part of a flexure is too acutely bent, there is 

 a rupture of the lowest syncline or of the uppermost anticlinal 

 stratum; but however twisted or reversed the flexures may be, there 

 is throughout the range a total absence of faulting in the sense of 

 fracture or dislocation of the strata. The very fact of the constant 

 succession of normal and abnormal flexures admits of co-ordinating 

 them as components of the two great folds which constitute one of 

 the characteristic features of the range. 



IV. The Stratigraphical Sequence. 

 Proceeding from the Mediterranean littoral upwards into the valleys 

 of the three main divisions, the lower hills, which form the outer 

 fringe of the range about 4 kilometres from the sea, are found to be 

 composed of much folded Eocene alberesi limestone and macigno 

 sandstone, succeeded by Cretaceous and then infra-Lias dolomitic 

 limestone strata. The town of Carrara is built on old alluvial 

 ■conglomerate resting on those strata. The infra-Lias thence extends 



