at Vesale, where the hills of Pian del Monte, Serretta della Valle, Monte Giustino, and, about four or five miles from these, Monte Specchio, are composed of a serpentine in all respects the same as that of Impruneta. In the neighbourhood of Reno, it is accompanied by white primitive limestone, of a scaly fracture and semi-crystalline grain; and at Pian del Monte it is covered by black transition limestone. In that near Vesale, native copper is frequently found. The simple minerals that generally accompany the serpentine of Italy are, diallage of different varieties, asbestus, talc, calcareous spar, limpid quartz, and calcedony; and at Miemo, that variety of bitter-spar described by Thompson, and named by him Miemite. But the mine ral which most generally accompanies it is the Jade tenace of Saussure; its colour is either white, greenish, or violet; it has in general little lustre, is of a scaly fracture, and slightly translucent on the edges. It is found in slender veins and nodules, incorporated with the serpentine, with which it has doubtless had a simultaneous origin; and it is sometimes so regularly distributed in small pieces, that the mass has a granitic structure. A mixture of this kind sometimes occurs, consisting of jade and serpentine, or of these two substances with diallage, or even of diallage and jade, without any serpentine; which last compounded rock has been called by the Florentines Granitone, Von Buch has given it the name of gubbro; but that term is applied in Tuscany to common serpentine. Granitone is found in almost every situation where serpentine exists; but the best opportunity of examining it, in all its relations, is at Figline, about three miles from Prato in Tuscany, where it is quarried for the purpose of being made into millstones. There is a section of it eighty or ninety feet high, where the internal structure of the hill may be seen: there are no signs of stratification in this rock, the continuity of the mass being only interrupted by irregular fissures. At Lornano, near Siena, there is a variety of granitone which deserves particular attention, from its resemblance to greenstone, and still more to sienite. It consists of a granular mixture of white jade and black diallage, which is so like hornblende, that they can hardly be distinguished in a polished specimen. Another granitone of the same kind, but having the component parts larger, is found at Bell' Aria. If the close analogies that exist between jade and felspar, and diallage and hornblende, be considered, it will not be difficult to admit the conformity which granitone has with greenstone and sienite. And in fact, true greenstone and serpentine have been found contiguous, in the neighbourhood of Massa di Maremma, and at Riparbella in the territory of Volterra.

The wide and extensive valleys of Foligno and of Terni, and the country round Otricoli, are covered with vast deposits of limestone gravel, which continue as far as Borghetto and Civita Castellana, where they are partly covered by volcanic matter. The same thing occurs in Tuscany, in the Casentino, in Valdarno Superiore, in the neighbourhood of San Quirico, and of Radicofani. Siena is built upon a mass of calcareous breccia, containing pebbles of grauwacke. The hills round Benevento in the kingdom of Naples, those of Eboli between Salerno and Pesto, and many others in the Valle di Bovino in Basilicata, are composed of an aggregate of the same kind of pebbles, with the exception of those of grauwacke; and vast tracts of the same kind of puddingstone occur in many parts of Romagna.

At the foot of the Apennines, there is a numerous series of hills which cover the greater part of the space comprehended between the high mountains and the sea, on both sides of Italy. They are distinguished, not so much by their lesser degree of elevation, which would be a vague and often a fallacious guide, as by the difference of their composition, and the epoch of their formation, which must have been posterior to that of the Apennines; in reference to which, they may be termed tertiary deposits. They are of very different degrees of elevation, and sometimes of very considerable height; the sandstone rock on which the capital of the little republic of San Marino is situated, be longs to this class; and Saussure has stated, (Voyages dans les Alpes), that the bottom of some vaults, which are near the summit of this rock, is from 320 to 330 toises above the sea.

These hills are composed of marl, and of sand and gravel lying over it; and a very slight examination is sufficient to show, that they have existed at the bottom of the sea at a period, geologically speaking, not very remote; for they are found to contain the trunks of trees almost in their natural state, the leaves of vegetables, the skeletons of fish, on which the dried flesh is still to be seen, and immense quantities of shells in which the gluten and colouring matter is often preserved; and frequently, the tendinous ligament which unites the two shells of the bivalves remains entire. While the strata of the calcareous mountains are always more or less inclined, sometimes vertical, and even turned over, the materials of these Sub-Apennine hills lie in general in a horizontal position.

The marl is of a bright grey, or dark leaden colour, inclining to blue, particularly when moistened. When it contains a considerable proportion of alumine, it becomes plastic with water, like common clay, and may be applied to the same purposes. It generally effervesces with acids, but is sometimes found with

out any calcareous matter; and it always contains scales of silvery mica. Besides a vast quantity of shells; bones of fish, and. other remains of marine animals, the leaves of trees, and trunks of bituminized wood, are often found in it; and sometimes it contains the bones of great quadrupeds. Sulphur is frequently found in it, and in some places accompanied by maltha, Petroleum is found in it at Miano, in the territory of Parma, and at Monfestino and Monte Zibio, in the territory of Modena. At the former place it drops from an ash-coloured marl, such as is of most common occurrence; but at Monte Zibio, it issues from a micaceous sandstone, that effervesces with acids, and gives sparks with steel. Sulphate of lime, both massive and crystallized, abounds in it every where; and the leaves of trees have been found in the gypsum between Voghera and Placentia. At Lecceto, in the territory of Siena, it contains quartz crystals of a brown colour, having both pyramidal terminations and frequently without the intermediate prism; these are called by the country people Lagrime di Martiri. The variety of sulphate of barytes, known by the name of Bologna stone, is found in this marl, and is common in other places, In the sulphur mines of the territory of Cesena, sulphate of strontian is found, perfectly limpid, and similar to that of Sicily. There are numerous brine springs, which rise in the marl, in the territories of Cesena, Siena, and Volterra, &c. That of Val di Cecina, near Volterra, yielded in 1810 fourteen millions of pounds of common salt, The only metallic substances that have been found in it, are iron pyrites, and concretions of oxide of iron and of bog iron ore, In many parts of the country occupied by this substance, sulphureted hydrogen gas rises, either directly from cracks in the ground, or from pools; and in many of these the water is very hot.

The siliceo-calcareous sand which lies over this marl, is found in almost as great abundance as the marl itself. Although the calcareous particles chiefly predominate in it, it contains also scales of mica, and a large proportion of quartzose sand. In some places it is wholly siliceous, with the exception of the oxide of iron, which gives it its yellow colour.

These tertiary deposits form a zone, which extends from Piedmont to the neighbourhood of Ascoli, thence into the Abruzzi, and through a great part of Puglia. All the hills in the territories of Asti, of Tortona, of the Oltrepò Pavese, of Placentia, Parma, Reggio and Modena, are composed of them, as well as the low hills in the departments of the Reno, Rubicone, Musone and Tronto; and traces of them have been observed in different places along the eastern side of Italy, as far as Otranto. On the Mediterranean side, these deposits have not been found

either in Eastern or Western Liguria, or in the adjoining pro vinces of Lunigiana and Garfagnana; but they appear in the territory of Lucca and the Valle di Nievole, and extend from thence by Valdelsa, Valdipesa, Upper and Lower Valdarno, the territories of Arezzo, Pisa, Volterra, and Siena, as far as Acquapendente. Following the road from this last place to Rome, they completely disappear, being covered by the tufi thrown out by the volcanoes of Acquapendente, Santa Fiora, Bolsena, Bracciano, Borghetto, and those which formerly existed in Latium; but, beyond the limits of the volcanic country, they reappear in several situations; as in the neighbourhood of Orvieto, Todi, and Otricoli, at Collevecchio in Sabina, at Monterone about half way between Rome and Civita Vecchia, &c. There are also some places where these deposits rise up from amidst the volcanic tufa: A remarkable example of this is to be seen near Rome; for the base of the hill of the Vatican is a blue marl, containing shells identical with those of Tuscany and Romagna. It is used in the manufacture of common pottery; and it was applied to the same purposes by the ancient Romans. It is covered by the siliceo-calcareous sand, of which the Aventine Hill, Monte Mario, and some eminences near Ponte Molle, are also composed. In going from Rome towards Naples, after passing the volcanic district of Velletri, nothing appears but solid limestone as far as Monte Sarchio near the Caudino Valley, where the blue marl with shells makes its appearance, being also visible in the neighbourhood of Benevento. At Ariano, and in the Valle di Bovino, as well as in several parts of Basilicata, the tertiary deposits appear; and M. Brocchi is of opinion, that they extend through a great part of Campania, and the whole of the Campi Phlegræi, under the volcanic matter scattered over that great tract of country. He is led to this conclusion, from what he obseved in the island of Ischia. The whole surface of that island is covered with volcanic matter; but below the tufa and lava, the blue marl containing shells may be seen in several places, particularly in the Monte Tabor near Casamicciole, where it lies under a current of grey lava, containing crystals of felspar.

The siliceo-calcareous sand is generally found covering the marl; but sometimes the marl cannot be seen except in deep excavations made by torrents. They do not, however, invariably accompany each other; for there are some places where the marl appears without any covering of sand; and in the neighbourhood of Andria, and of Bari in Puglia, the sand rests upon the solid limestone. It prevails greatly in Romagna; and the country between Macerata and Ancona is almost wholly composed of it. The remains of marine bodies are in many places so rare in it, that hardly a vestige of them can be found for the

space of many miles; but in other places they abound in it, and are found in greatest profusion in the territory of Asti in Piedmont.

It does not very frequently happen, that the rock on which the marl rests can be discovered: at Montalceto, however, in the territory of Siena, it is seen lying immediately upon the solid limestone and in some of the hills of San Quirico, it rests upon gravel composed of rounded fragments of limestone, and mixed with shells. The marl frequently contains beds of solid stone, having a conformable stratification with it, composed of minute grains of quartz and mica, with a calcareo-argillaceous cement. There are some precipitous rocks near Acqui in Piedmont wholly composed of it; and at the Punta degli Schiavi, near Pesaro, it is quarried for pavement, and conveyed by sea to Sinigaglia, Fano, and Rimini. A sandstone of a similar nature, got at Cingoli, is used for the same purpose at Macerata; and it is of this stone that the Santa Casa of Loreto is built; an observation rather unfortunate for the fame of the Santa Casa, if the same formation does not exist at Nazareth. This kind of sandstone has so great a resemblance to the Pietra Serena, the grauwacke of Tuscany, that they may, in specimens, be very frequently confounded with each other. The sand also acquires in some places a certain degree of induration, as in the hill of the republic of San Marino, and that on which Volterra is built, besides some other places.

Besides the tertiary deposits already mentioned, some other partial formations appear to have taken place at the same epoch, composed of fragments of rocks peculiar to certain situations. At the foot of the Ligurian Apennines, in the department of Monte Notte, there is found a considerable tract of sandstone, (or perhaps what may more properly be called a breccia), composed of fragments of noble serpentine, firmly agglutinated with scales of mica, pieces of quartz, &c. and containing, moreover, univalve and bivalve shells and madrepores. Another sandstone, consisting of a mixture of grains of quartz, calcedony, limestone and serpentine, and full of shells, is met with in the Modenese hills in the neighbourhood of Gajano, of Brusiano, of the Lago di Paullo, and at Gallinamorta. The mountain of the Superga near Turin, seems to be of the same description: M. Brocchi, who mentions it only incidentally, says that it is composed, even to the top, of a congeries of large rounded masses of the hardest serpentine and other rocks, imbedded in marl and calcareous sand; and Saussure, who gives a more detailed description of it, found the sand to contain shells, and, among others, an oyster, with the pearly lustre quite fresh. This mountain, by the barometrical measurements of De Luc,