Chapter XIV: Introduction: To Chapter IX

The geological strata found on the site of Rome and in its immediate neighbourhood divide themselves into three principal groups. The oldest of these is a marine formation, and exhibits itself upon the Vatican, Janiculum, and Monte Mario. The second, of which all the hills on the eastern bank and the district of the Campagna are composed, is of volcanic origin, and consists chiefly of beds of tufaceous matter erupted from submarine volcanoes and more or less solidified. The third, which appears in the hollows of the Tiber valley, is a fresh-water formation, and is found on the slope of the hills on both banks of the river.

[Sidenote: Marine formation.]

The oldest of these three groups belongs to the division of the tertiary period, called by Lyell the older pleiocene, as having had a fauna and flora in which the greater number of species were identical with those now living on the earth. These strata are of marine formation, and are similar to those which extend over a great breadth of Italy on both flanks of the Apennine mountains, reaching as far south as the point of Reggio in Calabria. Their lower bed consists of a bluish-grey clayey marl, which will be found in the valley between the Janiculum and the Vatican. Its marine origin is sufficiently proved by the fossils found in it, and the remains of sea-weed. This bed of clay is of a plastic nature, and is still used for making pottery, as it was in the time of Juvenal. Above it lies a stratum of yellow calcareous sand, which sometimes takes the form of loose sand with boulders, sometimes of a stratified arenaceous rock, and sometimes of a rough conglomerate. This may be seen outside the Porta Angelica, on the left, under the walls of the city, and in the Belvedere Gardens on the Vatican Hill. The Church of S. Pietro in Montorio is said to derive its name Montorio, monte aureo, from the yellow colour of this sand.

On Monte Mario an abundance of fossil shells, of the Ostrea hippopus and other varieties of sea shells, may be seen, plainly indicating the marine origin of this formation.

The only places within the actual walls of Rome where these tertiary marine strata are to be found, are the Vatican and the Janiculum. At the base of the Capitoline, in the subterranean vaults of the Ospitale della Consolazione, under the volcanic rock which forms the upper part of the hill, Brocchi found a stratum of calcareous rock and clay, which he affirms to be of marine origin, and to resemble the limestone of the Apennines.

[Sidenote: Volcanic formation.]

The second group of strata found on the site of Rome is one which is not confined to the neighbourhood of Rome, but is most extensively spread over the whole of the Campagna, the district of Campania, and a considerable part of southern Italy. The great mass of the Capitoline, Palatine, Aventine, Esquiline, Cælian, Viminal, Quirinal, and Pincian Hills, is composed of this formation. Geologists give it the general name of tufa, and divide it into two kinds, the stony and the granular. It is distinguished from lava by not having flowed in a liquid state from the volcano, and is a mechanical conglomerate of scoriæ, ashes, and other volcanic products which have been carried to some distance from the crater of eruption, and then consolidated by some chemical re-arrangement of their constituent elements. The harder kind of tufa, the tufa litoide, is a reddish brown, or tawny stone, with orange-coloured spots. These spots are embedded fragments of scoriaceous lava. It is hard enough to be used as a building stone, and has been quarried largely under the Aventine Hill near S. Saba, at Monte Verde, on the southern end of the Janiculum, and at other places near Rome, as at Torre Pignatara on the Via Labicana, at the bridge over the Anio, on the Via Nomentana, and at the Tarpeian rock.

This tufaceous stone presents itself in very thick banks, traversed by long vertical and oblique fissures, probably produced by the contraction of the mass on passing from a humid and soft to a dry and hard state. The Arch of the Cloaca Maxima, near S. Giorgio in Velabro, is built of this stone, and the inner part of the substruction of the so-called tabularium on the Capitol. Portions of the Servian wall were also built of it, and many stones which were taken from this wall are to be seen at the present day in the walls of Aurelian, near the gate of S. Lorenzo; and others have been laid bare by the railway excavations in the Servian Agger. Brick-shaped masses of it are found in the ambulacra of the Theatre of Marcellus, so that the use of it must not be restricted to the earliest times of Roman architecture. In fact, several buildings of the Middle Ages in or near Rome consist of this stone, as may be seen at the Fortress Gaetani, near the Tomb of Cæcilia Metella, and in the large tower at the side of the palace of the Senator.

[Sidenote: Freshwater formation.]

Fresh-water formations cover the bottoms of all the valleys in the district of Rome and in the whole of the Campus Martius, and ascend to a considerable height on the flanks of the hills and into the Campagna. They consist chiefly of sand, clay, gravel, and the stone called travertine, and of tufa beds which have been disturbed and then re-deposited. This re-deposited tufa has been the subject of some controversy. It was at one time thought to indicate that the lower tufa was also a fresh-water deposit, since it is sometimes found overlying the fresh-water formations. But no doubt now remains that it must have been formed by a re-arrangement in fresh water of previously deposited marine tufa beds. The water of the Tiber, at the time when these fluviatile formations took place, stood at such a height as to leave deposits upon the intermontium of the Capitol, and as high as the Church of S. Isidoro on the Pincian, and it must have partially removed and shifted the previously existing light and porous volcanic soil of the sea-bottom. Even the top of the Pincian was covered by this fresh water; for modules of calcareous matter, such as are deposited in fresh water alone, were found in digging the excavations for the fountain on the public promenade.

The surface of the broad river which then existed, seems, in fact, to have been at from 130 to 140 feet above the present surface level of the Tiber, and its water must have been more surcharged with alluvium, derived from sources with which the present river is no longer connected.

Among the fluviatile deposits, argillaceous marl beds now play an important part. They intercept the water as it descends from the hills, and impede its descent to the river, thus furnishing supplies to the wells in Rome, but rendering the soil less dry and healthy. The greater portion of these strata consist of a mixture of sand and clay. The ridge between the Campo Vaccino and the Coliseum, on which the Arch of Titus stands, is formed almost entirely of these mixed strata of clay and sand. To prove the fresh-water origin of these deposits, we need only refer to the modules of travertine and the shells of lacustrine animals which they contain. Such species of fresh-water shell-fish could not live in turbid and rapid water like that of the Tiber as it now is, and we must therefore conclude from their presence that the waters of the Tiber valley where such fossils are found were once in a semi-stagnant state. That there was also a period of violent movement during the prevalence of this lacustrine era is testified by the quantities of matter brought from a distance and accumulated at considerable altitudes, and by the size of the pebbles and boulders which have been rolled along by the stream. But before a more accurate investigation of facts shall have been made, it will be impossible to distinguish these two periods of stagnation and rapid movement from each other.

[Sidenote: Tiber water.]

The river water has no longer the power which it once possessed of depositing the travertine which we find lying in thick beds upon the slopes of some of the hills of Rome, and from which the larger ruins are all built. This travertine is formed from carbonate of lime which the waters take up as they pass through the soil containing it. In order to give the water the power of holding this carbonate of lime in solution, a certain quantity of carbonic acid gas must be present in it. When by means of the rapid movement of the water or from other causes this gas becomes disengaged, it leaves the carbonate of lime behind in the shape of a hard stony deposit. This natural process of petrifaction is familiar to all who have seen the Falls of the Anio at Tivoli, and the way in which the artificial canals of running water in that neighbourhood are choked by limestone concretions, and it may be seen in all vessels made use of to boil water which is impregnated with lime. The more violent the agitation of the water the more rapid is the disengagement of the carbonic acid gas, and the consequent settlement of the lime. This process is accompanied, in most places where it can be seen, by the presence of sulphuretted hydrogen, which produces a white colour in the water by depositing the sediment called gesso by the Italians. Hence an explanation of the ancient name of Albula given to the Tiber is easy. In the period when the Tiber had the power of depositing travertine, its waters were much more strongly impregnated not only with carbonate of lime, but also with gesso, which gave a white tinge to the water as it now does to the sulphureous waters near Tivoli. The same colour was characteristic of “the white Nar, with its sulphureous stream,” Virgil’s description of the chief stream of the central Apennines.

[Sidenote: Climate.]

The subject of the climate of Rome is naturally connected with that of the nature of the soil and configuration of the hills and valleys.

It is not difficult to see why the peculiar geological formation of the Campagna proves, without careful drainage, extremely deleterious to health. We have there a district containing numerous closed valleys and depressions in the soil without outlet for the waters which naturally accumulate. The tufa which composes the surface seems commonly to take the shape of isolated hills with irregular hollows between them, so as to impede the formation of natural watercourses. Under this tufa is a quantity of marl and stiff clay, which retains the water after it has filtered through the tufa, and sends it oozing out into the lower parts of the country, where it accumulates, and, mixed with putrescent vegetable matter, taints the surrounding atmosphere. A want of movement in the air caused by the mountainous barriers by which the Campagna is enclosed is another source of malaria.

The sites of Veii, Fidenæ and Gabii, once the rivals and equals of Rome are now entirely deserted except by a few shepherds and cattle stalls. Along the coast stood Ardea, Laurentum, Lavinium and Ostia, all of them towns apparently with a considerable number of inhabitants. Of these Ostia is now a miserable village, Ardea contains about sixty inhabitants, while Laurentum and Lavinium are represented by single towers. During a part of the year the ancient Roman nobility lived in great numbers on these very shores now found so deadly. Pliny the younger describes the appearance of their villas near Laurentum as that of a number of towns placed at intervals along the beach, and he writes an enthusiastic letter in praise of the salubrity and convenience of his own house there.[124] Lælius and Scipio used to make the seaside at Laurentum their resort, and to amuse themselves there with collecting shells.[125] Nor was it only on the seacoast that the country villas were placed. Six miles from Rome on the Flaminian Road, at the spot now called Prima Porta, there stood a well-known country house belonging to the Empress Livia, part of which has lately been excavated.[126] This was a highly decorated and commodious house, as the rooms which have been discovered, in which was found a splendid statue of Augustus, and the busts of several members of the imperial family, amply testify. The views from this spot over the Campagna and the Sabine Hills are most lovely, but the contrast between the beauty of nature and the haggard and fever-stricken appearance of the modern inhabitants is melancholy enough. A few squalid houses occupied by agricultural labourers stand by the roadside. Among their tenants not a single healthy face is to be seen, and even the children are gaunt, hollow-cheeked, and sallow in complexion. No wealthy Roman would now consent to live on the site of Hadrian’s stately villa in the Campagna near Tivoli. Tivoli itself, which Horace wished might be the retreat of his old age, and which was celebrated as a healthy place in Martial’s time, has now lost its reputation for salubrity, and is known as--

Tivoli di mal conforto,
O piove, o tira vento, o suona amorto.

Strabo speaks of the now desolate district between Tusculum and Rome as having been convenient to live in. But there is no need to multiply proofs which might be gathered from all sides of what is an acknowledged fact, that the malarian fevers of the present day were not nearly so deadly in the classic times of Rome, or even in the Middle Ages. The troops of labourers who, fearing to pass the night in the country, are met returning to Rome every evening, the forsaken towers and buildings which stand rotting everywhere about the Campagna, all tell the same tale of a pestilence-stricken district.

The peculiar physical features of the district have had no little influence in determining the mode in which the population was grouped in ancient times. Everywhere we find the hills of Rome reproduced on a reduced scale. Small isolated flat-topped hills, irregularly divided by deeply cut watercourses, and edged with steep low cliffs, afford numerous sites for the settlement of limited independent communities. Such are the hills on which Laurentum, Lavinium, Fidenæ Antemnæ, Ficulea, Crustumerium and Gabii stood, and similar places abound in many parts of the district. Such hills afforded suitable sites for the small fortified towns with which ancient Latini was thickly studded. Their sides can be easily scarped so as to afford a natural line of defence, and they are in general fairly supplied with water from numerous land springs.

Thus, although the general aspect of the Campagna is that of a plain country, yet the main level of its surface is broken by numerous deep gullies and groups of hillocks.

The tertiary marine strata, already described as forming the Janiculum and other hills upon the right bank of the Tiber, do not rise to the surface in the Campagna, except on the flanks of the Æquian and Sabine hills. These hills themselves consist of great masses of Apennine limestone jutting out here and there into the spurs upon which some of the more considerable cities of the Latin confederacy stood, as Tibur, Præneste, Bola and Cameria.

The Alban Hills form a totally distinct group, consisting of two principal extinct volcanic craters somewhat resembling, in their relations to each other, the great Neapolitan craters of Vesuvius and Somma. One of them lies within the embrace of the other, just as Vesuvius lies half enclosed by Monte Somma. The walls of the outer Alban crater are of peperino, while those of the inner are basaltic. Both are broken away on the northern side towards Grotta Ferrata and Marino, but on the southern side they are tolerably perfect.

From the legendary times, when Latinus, Evander, Æneas, and the rest of Virgil’s heroes are supposed to have occupied the great plain of Latium, down to the final settlement of the district by its subjection to Rome in B.C. 338, the Roman Campagna was peopled by communities chiefly living in towns. Etruria on one side and Latium on the other, contained confederacies of independent cities, with one or other of which the Romans were constantly at war. Etruria gave way first, and after the fall of Veii in B.C. 395, the Roman dominions extended northwards as far as the Lago Bracciano and Civita Castellana.

At that time the great confederacy of Latium, though Alba was destroyed, still existed under the Hegemony of Rome as the successor of Alba, and numbered Tibur, Præneste, Tusculum, Aricia, Antium, Lanuvium, Velitræ, Pedum, and Nomentum among its members. But after the victories gained by the consuls of the year B.C. 338, the absorption of the Latin cities made rapid progress, and the character of the population of the Campagna began to be completely changed.[127] In this, the second period of the history of the Campagna, the towns were gradually reduced to mere villages, the small farmers disappeared, and the land was occupied by the immense estates (latifundia) of rich proprietors cultivated by hordes of slaves. Such is the condition in which we find the Campagna in the time of Cicero.[128] The great villas which strew the ground everywhere in the neighbourhood of Rome with their ruins were then constructed, and the colossal aqueducts which served not only to supply Rome with water but also to irrigate the farms and country seats of the Campagna.

There seems to have been a constant tendency during the later republic and early empire to reduce the amount of arable land, and to increase the extent of pasturage in the Campagna. Thus the country was rendered less and less healthy, and Rome became gradually more dependent than ever on foreign countries for her supply of corn.

The last phase of the history of the Roman Campagna is the most melancholy. The aqueducts were nearly all destroyed by the Gothic army at the siege of Rome under Vitiges in A.D. 536, and the great country seats of the Roman nobles and princes must have been ruined by the successive devastations of Roman territory during the fifth and sixth centuries in which the Lombards were the principal actors. Agriculture ceased, and the few villages and country houses which remained soon became uninhabitable during a great part of the year, in consequence of the increase of malarious exhalations arising from the uncultivated state of the soil, or were rendered unsafe by the lawless bands of ruffian marauders who infested the open country. Such is in the main the condition of the Roman Campagna at the present day, for the most part a waste of ragged pastures without human habitations, and wild jungles tenanted only by foxes, bears, and other wild animals.

The above remarks will serve to show that after B.C. 338 the Campagna became deprived of all historical interest except as the summer residence of the great Roman proprietors. Its history belongs almost entirely to the early times of the Roman Republic.