1850.] MURCHISON— VENTS OF HOT VAPOUR IN TUSCANY. 381 



north of Parma, seems to have been the grand centre of serpentine 

 eruption, from whence such lines radiate, as marked by the protru- 

 sion at intervals of igneous rocks and the bands of metamorphosed 

 strata which constitute the loftiest ridges of Italy (see fig. 6, p. 383). 

 In this way, the serpentine bosses of the Apennines, between Bologna 

 and Florence, that trend from N.W. to S.E. — i. e. from the region 

 of chief eruption — though divergent from the line of the Apuan Alps, 

 and Tuscan Maremma, ar^ exactly coincident with the major axis of 

 the Apennines or great back-bone of Italy, the culminating points 

 of which, as at the Gran Sasso d' Italia, 9530 feet above the sea, are 

 composed of eocene (nummulitic) and cretaceous rocks reposing on 

 Jurassic. 



Again, if we turn from the east and look to the other great band 

 of eruption to the west of the coast of Italy, as marked by serpentines 

 protruding through the cretaceous and eocene deposits of Corsica, 

 we see (as graphically laid down by Pareto *) that it marks nearly 

 a meridian line. Looking then at Italy on the great scale, the geo- 

 logist may, I think, satisfactorily connect its dominant physical fea- 

 tures with former causes of upheaval. He sees that, as it is in the 

 highly convulsed and broken-up region where the Apennines bend 

 round to become confluent with the Alps, the greatest masses of 

 serpentine have been emitted, so, exploring southwards from this 

 grand focus, he observes that bands of the same molten matter 

 have been intruded into divergent cracks and fissures in the crust 

 of the earth, and extend in long linear directions to the S.E., S.S.E., 

 and S. Geological investigation establishes, indeed, not only this 

 fact, but also the important point, that such igneous matter was 

 simultaneously emitted ; since it has alone broken through and me- 

 tamorphosed sedimentary strata of the same age through several de- 

 grees of latitude. Now, as few parts of Italy contain strata of higher 

 antiquity than liasso-jurassic, and as there is no evidence that its 

 submarine accumulations had ever been raised into dry land before 

 the cretaceous and nummulitic rocks were accumulated upon them, 

 we have a fair right to infer, that the linear eruptions of serpentine 

 and their accompaniments of gas and heat, absolutely furnished the 

 Peninsula with those chains of hard and altered strata (each con- 

 taining subordinate parallels) whose features and contents have been 

 described on a previous occasion. In short, there is no reason to 

 believe, that Italy had any well-defined terrestrial existence until the 

 period of the post-eocene serpentinous eruptions. As Corsica, how- 

 ever, is only the northern prolongation of Sardinia which contains 

 Silurian fossils, and as both islands are characterized by a meridian 

 chain of ancient crystalline rocks, it is clear that a very ancient mass 

 of land ranged in that direction, as further proved by its old cry- 



* The reader who wishes to become acquainted with the various lithological 

 characters of the rocks classed under the head of Serpentine, and which were all 

 emitted at the post-nummulitic period, must consult the works of Pareto on Li- 

 guria Marittima, and on Corsica, both illustrated by excellent geological maps. 

 Although the Marquis Pareto, following preceding authorities, has classed the 

 nummulite limestone with the chalk, I trust he will now agree with me. 



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