294 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DcC. 13, 



mable) therein, and other pomts of great interest, must now be passed 

 over. 



If a geologist examined the district of Monte Bamboli only, he 

 might form a conclusion that the beds with coal at once succeeded to 

 the alberese limestone ; but at Monte Massi he sees that one under- 

 lying conglomerate is formed out of that rock, and that another, de- 

 rived from the serpentines associated with it, forms the absolute base 

 and support of this capacious and very remarkable coal tract, which 

 although referred to the miocene age and clearly subjacent to all the 

 lower subapennine, has more the aspect of an old coal-field than any 

 other of similar date with w-hich I am acquainted*. 



I do not pretend to be able satisfactorily to define the exact limits 

 and relations of all the members of the tertiary accumulations of dif- 

 ferent parts of Central Italy. In the southern part of Tuscany it was, 

 however, clear to me, in a traverse which I made from Volterra to 

 Siena, and also by examining the deep railroad cuttings to the north 

 of the latter city, that the whole of the pliocene or subapennine series 

 properly so called, i. e. the blue shelly marls (1) and their overlying 

 yellow sandstone (panchina) and conglomerate (2), are there sur- 

 mounted by the freshwater limestone (3), which occupies plateaux 

 between Monte Reggioni and Colle, and in a deep denudation at the 

 latter place is seen to rest on shelly subapennine strata, as expressed in 

 the opposite diagram (fig. 39). Near Castello St. Geminiano on the 

 west, the yellow subapennine sands with shells rise out rapidly from 

 beneath this tufaceous limestone with its Lymnsese, Planorbes and 

 other shells, and at Monte Reggioni on the east a similar infraposition 

 is equally clear. Towards Siena this freshwater formation becomes 

 a massive travertine, and constitutes undulating hills of hard and 

 tough cavernous rock ; among the lower masses is a very coarse con- 

 glomerate with huge angular fragments of Apennine limestone, often 

 two and three feet in diameter. The strata of reddish colours, which 

 are cut through by the railroad towards the source of the Staggia, are 

 evidently a portion of this same irregularly deposited and block tra- 

 vertine, the whole of which overlies the subapennine group. In this 

 tract there are considerable fractures, and wedge-shaped masses of 

 the shelly blue marl are here and there forced up against the over- 

 lying conglomerate and travertine. 



The more detailed order of this district, which cannot, however, 

 be expressed in a general woodcut, seemed to me to exhibit in a de- 

 scending series beneath the vegetable soil, 1st, coarse alluvia ; 2nd, 

 finely laminated sandy loam ; 3rd, lacustrine limestone with Lymneeae 



* For details respecting these coal tracts of the Tuscan Maremma, see Professor 

 Savi's work, " Sopra i carboni fossili dei terreni mioceni dalle Marerame Toscane, 

 Pisa, 1843." Among the fossils he cites bones, possibly belonging to carnivora, 

 and teeth of rodentia, Mytilus Brardi (Brongn.), opercula of univalves, and imper- 

 fect casts which may belong to Buccinum, Fusus and Cardiacese. The character- 

 istic plants are Palmacites, a Musacea termed Uraniophyllites by Prof. Pietro 

 Savi, with leaves of various dicotyledons (oak, plane, elder, cornel), cones of 

 pine, «&c. Prof. Pilla has also described these tracts in a memoir entitled " Sopra 

 il carbon fossile trovato in Maremma," Florence, 1843 ; and in a work called 

 "Breve Cenno della richezza minerale delle Toscana," Pisa, 1845. 



