GEOLOGICAL HISTORY OF SERPENTINES. 193 
horizon. The writer had, in 1881, the pleasure of examining at Bologna, in company with 
with James Hall, a collection of these fossils. Above the Ordovician beds in Sardinia is 
found a great mass of limestone, of undetermined age, remarkable for its beds and included 
masses of lead, silver and zinc-ores. 
§ 75. We have now shown that these crystalline rocks which, in parts of the mainland, 
are directly succeeded by tertiary sediments, are in different areas overlaid by various sub- 
divisions of the mesozoic, and finally by carboniferous, Ordovician and Cambrian sediments, 
thus disproving the views of the older geologists who assigned to these same crystalline 
rocks a paleozoic or a mesozoic age. It is instructive to mark the steps by which this view, 
has, in the progress of investigation, been left behind. In Neri’s section the older gneiss and 
the pietre verdi proper are called azoic or protozoic, but the recent gneiss is conjectured 
to be paleozoic. Lory, however, included the latter in the primitive series, but claimed 
the lustrous schists as altered trias, while later, Gastaldi, and with him Favre, placed even 
these in the paleozoic, until at last we find Gastaldi adopting the conclusion first put for- 
ward by the present writer in 1872, that the whole of these crystalline rocks are to be 
referred to pre-Cambrian time. 
§ 76. The story of the crystalline marbles of Carrara, now included in this: series, is 
not less instructive. They were regarded as eruptive by Savi, who taught that dolomites 
and limestones had been poured out in a fused state, alike in secondary and in tertiary 
times, * and even indicated what he supposed to be centres of eruption. The marbles of 
Carrara, with their associated schists, have since been called cretaceous, liassic, rhaetic, infra- 
carboniferous and pre-paleozoic. | They were in 1874, in the second part of Gastaldi’s 
Studii, included in the rocks of the pietre-verdi zone, the term being then used in its larger 
sense, as embracing not only the true pietre verdi, but the whole crystalline series above 
the ancient gneiss. 
§ 77. This was also clearly stated by Jervis, in his elaborate work on the mineral 
resources of Italy ¢ a veritable treasury of information, most carefully and systematically 
arranged. In his first volume, in a tabular view of the geology of the Alps, he had already 
adopted the views of Gastaldi, and placed the whole of the crystalline stratified rocks 
above the ancient gneisses in a pre-paleozoic group, which he regarded as synonymous 
with the pietre-verdi zone. In his second volume, in a similar tabular view of the geology 
of the Apennines and the adjacent islands, he further insists upon the same view, and 
puts above the ancient gneiss, in what he calls the pre-paleozoic period, the great series of 
“ stratified azoic rocks,” including not only the ophiolites, and the recent gneisses and other 
crystalline schists, but the saccharoidal and compact marbles of the Apuan Alps (loc. cit. 
p. 9.) It is to be remarked, as shown both by Jervis and Gastaldi, that this great younger 
crystalline series is the metalliferous zone of Italy, containing much cupriferous and nicco- 
liferous pyrites, in veins and interstratified beds, together with crystalline iron-ores, lead, 
zine and gold. 
§ 78. With the general succession of the Alpine rocks already given, we may compare 


* Boué, Guide du géologue voyageur, IL., 168. For the views of others as to the eruptive origin of crystalline 
limestones, see my Chemical and Geological Essays, p. 218, 
+ For a notice of some of the various views which have been put forward with regard to the age of these 
marbles, see Lebour in the Geological Magazine for 1876, pp. 287 and 383, 
{ I Tesori Sotteranei del’Italia, 3 vols. 8vo, Turin, 1878-1881, 
Sec. IV., 1883. 25 
