162 Abstracts of Foreign Memoirs. 
Volterra, near which ancient town are the celebrated copper-mines 
of Monte Catini and the soffioni boraciferi, or hot vapours containing 
minerals, now conveyed into pools of water and yielding large sup- 
plies of the borate of soda (the borax of commerce). Few parts of 
Italy are more interesting to the geologist, and he could not find a 
guide more intelligent, lively, or trustworthy than M. Savi. 
Almost the whole province lies to the south of the Arno, and it 
includes about seventy miles of coast, the width of the belt varying 
from ten to twenty miles. The Arno and the Cecina cross it at 
right angles; the coast is generally low, and often marshy, and there 
are ranges of hill parallel to the coast a few miles distant. Some 
idea of the geological interest of the district may be obtained from 
the statement, that it presents marked varieties of Paleozoic rocks, 
together with Liassic, Jurassic, Upper and Lower Cretaceous, Upper 
and Lower Eocene, very varied Miocene, Pliocene, and Post-pliocene 
deposits. Some of these are broken through by serpentines, trachytes, 
and porphyries, or are penetrated by modern volcanic vapours. The 
whole district is subject to earthquakes. 
The result of a very superficial glance at the orographical struc- 
ture of Tuscany shows—(1) that it presents three varieties of surface-— 
mountains, hills, and plains ; (2) that the mountains form geologically 
three chains—the Apennines, the metalliferous chain, and the ser- 
pentine chain; (3) that the hills are also of three kinds—Miocene, 
Pliocene, and Recent. All of these but the Apennines exist in the 
province of Pisa. The Paleozoic rocks are chiefly of the Carboni- 
ferous period, and of the kind known locally as verrucano, consist- 
ing of clayslate, taleschist, &c., and they are well marked by 
occasional fossils, both vegetable and animal. ‘They are limited to 
the northernmost part of the province, where it adjoins the territory 
of Lucca, and the mountains enclosing the celebrated Baths of Lucca. 
Rocks apparently Triassic are present in small quantity between the 
verrucano and the River Serchio, and on both banks of the Serchio. 
They are covered with Liassic and Jurassic rocks to a limited extent. 
These recur on the flanks of Monte Calvi, at the southern ex- 
tremity of the province, where they are brought up by trachytic and 
porphyritic rocks. Elsewhere they are covered by newer deposits. 
The Cretaceous rocks are also exhibited on Monte Calvi; the alberese 
overlying the Jurassic rocks on the southern side. Other examples 
were seen on the flanks of the serpentines near Monte Catini, and 
they doubtless extend below the Miocene and Pliocene rocks to the 
north. They occur again to the east of Volterra in similar position, 
but the whole amount exhibited at the surface is small, and the 
rocks are almost entirely Upper Cretaceous. 
Eocene rocks, both Nummulitic Limestones and the rock called 
macigno, are much more extensively developed, and occupy large 
tracts in the districts south of the Cecina. It is chiefly the upper 
member that is seen. This rock also is called alberese; but it is 
quite distinct from the Cretaceous alberese. It is pierced through 
by the trachytes of Monte Calvi, and also by numerous smaller 
eruptions of serpentine. ‘These are seen in three groups—one near 
