TRANSACTIONS OF SECTION C. 703 



2. Oastaldi on Italian Geologij and the Crystalline liocJcs.^ 

 By T. Steret Hunt, LL.B., F.B.S. 



The autlior recalled the fact that, in discussing in 1883 the geological relations 

 of serpentines^ he bad maintained that, although not confined to Archtean rocks (in 

 which they are found at various horizons) those of Italy, believed by some 

 geologists to be in part of Tertiary age, are, so far as his studies go, wholly 

 Archffian, in accordance with the views set forth by Gastaldi. He had in the paper 

 in question which, revised and augmented, forms Chapter X. of his Mineral 

 Physiology and Physiograpby (Boston, 1886) resumed at some lenjjth the work 

 of this eminent geologist, left incomplete by his premature death in January 1879, 

 and had given a list of his printed papers on Alpine geology so far as known to 

 the writer. He had then proceeded to review the work of various other Italian 

 geologists who had maintained the Eocene age of certain serpentines in that region, 

 and from his own observations of certain localities in the Apennines of Liguria, 

 and of Prato in Tuscany, endeavoured to show that the serpentines and other roclis 

 of the ophiolitic group in these localities existed in their present condition in the 

 seas in which were deposited the Eocene strata, which latter, by subsepient 

 terrestrial movements, had been disturbed, broken, and even inverted, so as to 

 seem to pass beneath the ophiolites. The indigenous and neptunian character of 

 serpentines, maintained on stratigi-aphical grounds by Emmons, Logan, and the writer 

 in North America, was not only held by Gastaldi and Delesse, but is taught by 

 Lotti, by Stapff, and by Dieulefait in emphatic terms, while the plutonic hypothesis 

 of their origin lias been so far modified by its modern Italian advocates that they 

 now suppose the serpentines due to submarine eruptions of a hydrous magnesian 

 mud, which subsequently consolidated into serpentine and even into chrysolite. It 

 is difficult to admit any other than a neptunian origin for the stratiform ophical- 

 cites into which the massive serpentines often graduate. 



While the writer's conclusions as to the localities named were thus in periect 

 accord with the views of Gastaldi, he was not then aware that this geologist had 

 ever examined them. In July 1878, however, while in London, the writer received 

 from Gastaldi a long epistle dated at Turin, July 20, and after perusing the first and 

 last pages, and answering what was of immediate moment, laid it aside, unread. 

 The letter was then by an accident mislaid, and only recovered during the present 

 year. In a translation of this letter, which is now given, Gastaldi presents 

 (ostensibly for the International Geological Congress of 1878) a brief summary of the 

 views set fortb at length in his published papers and in the writer's volume above 

 named. He further adds that he had then just returned from a special study of 

 the ophiolites of the Ligurian Apennines and of those of Prato, and had found 

 convincing evidence that these were, like those elsewhere examined Idv him, protrud- 

 ing portions of the ancient 2n'ef re verdi zone, identical with that of "the Alps, from 

 which the Apennines cannot be distinguished either geologically or geographically. 



The vast series designated by him as the jr.etre verdi zone overlies, according to 

 Gastaldi, the ancient central or primary <rneiss (generally granitoid, but including 

 quartzites and crystalline limestones with graphite, &c.), and has a thickness of 

 many thousand metres, embracing three subdivisions. The lowest of these, some- 

 times called by him the pietre verdi proper, includes serpentines, diorites, 

 euphotides, chloritic schists, Sec. ; the second is designated by him recent gneiss 

 and granite with mica-schists and hornblendic rocks ; while the third consists in 

 great part of soft argillacHous or lustrous schists, with included quartzites, marbles, 

 statuary, and banded dolomites, and occasionally also serpentines, the presence of 

 which led Gastaldi to include it with the two p-ecedinir subdivisions in his great 

 pietre verdi zone ; a name which the present writer, with Neri and others, would 

 restrict to the lower subdivision, regarded by him as the equivalent of the Huronian 

 of North America ; the underlying or central gneiss being the Laurentian ; the 

 recent gneiss and mica-schist, the Montalban or "White Mountain series, and the 

 upper subdivision, the Taconian or Lower Taconic of North America; the wholly 



' Published in extenso in the Geol. Mag. for December 1887. 



