Professor Hoffmann on the Geology ofMassa Carrara. 121 



vesicular, in general crystalline, limestone, which often seems to 

 indicate dolomite, and in the lower part passes gradually into 

 snow-white saccharine marble. Under the marble, and insensi- 

 bly encroaching on it, appear the mica and talc slates. With 

 these end the series of strata here observable ; for at the top of 

 the pass, an opposite dip of the strata takes place, and on the 

 other side, at Tenerano, the superimposed Macigno again ap* 

 pears. What this section in the Tecchia exhibits within nar- 

 row limits, is seen on a larger scale in all the cross ravines 

 of the mountain group of Carrara. In the central mass 

 further in the interior of the mountain group, the more or 

 less pure marble always occurs under the external limestone 

 layer. Its largest and purest mass lies near Turano, and 

 thence to the summit of the Monte Sacro. The talcslate is 

 connected with it in the same way as on M. Altissimo, and 

 divides the marble on the great scale into large distinct beds> 

 which are parallel to the general dip ; sometimes such separa- 

 tions of strata are indicated only by delicate scales of silverj 

 mica, or talc. This, hitherto termed primitive limestone, passes 

 gradually into compact vesicular limestone, abounding in petri* 

 factions, so that there can be no doubt as to the connexion in 

 their formation ; nay, even a perfect alternation takes place of 

 all these rocks. Between Carrara and Calonata, always pro- 

 ceeding in the descending order in regard to superposition, we 

 still find the porous and compact fossiliferous limestone, then, 

 where the valley of Miseglia begins, first a rock dipping under 

 a high angle to the south-west, an intermediate link between the 

 slaty marls of the secondary strata and the true clay-slate, and 

 this on the lying side passes into a beautiful talc-slate ; the talc- 

 slate forms a large pure layer, and is succeeded by an underlying 

 portion of beautiful white marble, veined with black. This 

 marble is followed again by an alternation of stratified black 

 limestone with slate, separated into plates one inch in thickness. 

 The slate is here more like mica-slate, and the limestone is more 

 rarely quite compact, and contains no petrifactions. Imme- 

 diately under this alternation of limestone, a slate follows the 

 great mass of the marble. Marble and dolomite are here one 

 and the same thing, and ascend uninterruptedly to the summit 

 of M. Sacro, If we go beyond this mass in an eastern direc- 



