its main topographical characteristics have been evolved, there is
a special fascination in pursuing the investigation of particular
features and trying to trace their origin in detail. Take, for
instance, the story of the valleys. I can hardly imagine a more
delightful task for a lover of geology than to work out the history
of the Tiber--an investigation which, from the point of view we are
here considering, still remains to be accomplished. Even from any of
the hills of Rome it is not difficult to follow some of the stages
of this history. We have seen that the river may have flowed at first
south-westward, from its estuary among the Todi hills, across the site
of the volcanic district to the sea somewhere north of Civita Vecchia.
We have further found that the volcanic eruptions, which gave rise to
the long line of heights between Aquapendente and Bracciano, probably
blocked up the older channel, turned the stream towards the southeast,
and for many miles kept it from once more bending seawards until at
last it found its escape across the low ground of the Campagna. Looking
from the Monti Parioli up the broad strath, we see the Tiber meandering
through its flat alluvial plain which, from a width of a mile and a
half, suddenly contracts immediately below us to less than a third
of that space. The meaning of this constriction will be understood
if we remember the position of the sheet of hard travertine to which
allusion has already been made. When the river began to flow across
this tract of country, the general level of the ground, not yet reduced
by prolonged denudation, was no doubt a good deal above what it is now,
and the bed of the stream may even have lain at a higher level than the
tops of the present ridges on which Rome is built. After traversing the
volcanic plain, the Tiber reached the western margin of this tract near
where the Monti Parioli now rise. It then flowed southwards between
the slopes of Monte Mario and the edge of the volcanic accumulations.
It cut its way downward through the upper parts of the tuff, and at
length encountered the sheet of travertine near the Ponte Molle. This
hard stone would form for a time a barrier to the erosion which must
have been comparatively rapid among the soft overlying tuffs. The
river, ponded back into a lake-like expansion in front of the mouth of
the Anio, was made to sweep in a wide curve into the softer Pliocene
strata of the Vatican ridge on the right bank. The travertine extends
through the Parioli ridge and round the base of the Pincian Hill. A
similar rock emerges in the precipitous bank on the west side of the
Aventine, and farther south at the Monte Della Creta, opposite the
Magliana bridge. Even where this resisting stone disappears, its place
has often been taken by a variety of tuff much more compact than the
usual rock of the district. It is the presence of these more durable
kinds of stone that has curbed the erosive progress of the river on
its left bank, through the area on which the city stands. Where these
barriers to its action were locally absent, the river was able to
scoop out bays and recesses among the softer parts of the tuffs. The
Capitoline, Palatine, Aventine and Celian hills have survived as more
or less isolated eminences, owing to their fortunate possession of a
more obdurate stone than the loose granular tuff of the surrounding
Campagna. They once rose as islands out of the flood plain, and their
steep sides, such as the Tarpeian rock and the cliffs that surrounded
the original Roma Quadrata, owed their precipitousness mainly to the
scour of the Tiber as it swept past their base.
Hardly less attractive would be the task of deciphering the history
of the rough, craggy ridges and broad, smooth plateaux which form
such distinctive features in the scenery of the Campagna. In this
investigation, we would mark how these differences of contour have
mainly arisen from variations in the character of the volcanic tuff.
Where the rock has possessed little coherence, and has consequently
yielded more easily to the weather, it has crumbled away for the most
part into gentle slopes which have been more or less shielded from
further decay by a mantle of vegetation. But where the loose ashes and
scoriæ have been accompanied with much fine dust, and have consolidated
into a hard, compact stone, this material has survived to form the more
rugged features of the scenery. Every stage in the progress of the
sculpture may be instructively seen at the edge of the volcanic plain,
where it winds round the projecting spurs and into the retreating
hollows and bays of the great Apennine wall. Little imagination is
needed to picture this plain as a sea-floor over which the waves
rolled along the base of the mountains. But when this sea-floor was
raised into land, the torrents from the uplands began to dig out
of it winding channels, which were gradually deepened into gullies
that unite into wider ravines as they descend. Between these defiles
portions of the old plain have been left, along the sides of which
the successive sheets of tuff run as bold ribs or as green slopes,
according to their relative durability. Here and there one of these
outliers, girdled round with vertical walls of rock, rises as an almost
inaccessible platform above the ravines around, and has served as the
site of some prehistoric citadel or of some medieval fortalice. All
over the Campagna, indeed, from the very earliest ages, advantage has
been taken of such defensible sites. They were selected as positions
for the cities of Latium and Etruria, art often aiding to scarp their
sides into steeper and more continuous crags than Nature had provided.
They supplied convenient sites for the abundant _suburbana_ or country
villas and manors of ancient Rome, and they were used over again in
the stormy Middle Ages for the erection of fortified farms and refuge
towers.
A discussion of the history of the Campagna would probably be regarded
as culpably incomplete without at least a reference to the causes
that have led to the solitude and desolation of the region. There can
be little doubt that in the days of the Empire the plain was thickly
peopled and well cultivated. It could not have been the fever-stricken
place which it has since become. The wealthy Romans were delighted to
escape from the tumult of town to their quiet and healthy retreats in
the country where, amid the pleasures and occupations of their farms,
they could spend the hottest, and what is now the most insalubrious,
season of the year. Yet there would seem to have been even then
malarious tracts in the Campagna. Cicero boasts of the healthiness
of Rome, compared with the pestilential character of the surrounding
district. The porousness of the tuff all over the country, as I have
above remarked, allows a large proportion of the rain to sink at once
under ground, instead of flowing off into runnels and brooks. The water
finds its way again to the surface at lower levels, either in the form
of springs or oozing from the soil. In the hollows where the drainage
accumulates, stagnant pools and marshes arise, which become the great
nurseries of malaria. In the most flourishing days of Rome, when the
whole surface of the Campagna was populous and in full cultivation,
attention was alive to the importance of drainage. Probably many of the
swampy tracts, whence mosquitoes now swarm, were then dry and turned
over by the plough or spade. The general processes of agriculture
prevented the accumulation of stagnant water and rotting vegetation.
But with the fall of Rome and the devastation of the Campagna by
successive hordes of barbarians, the villas fell into ruins, the
inhabitants were in great measure extirpated, the farms remained
untilled, the soil was left untouched, the water was allowed once more
to gather and the vegetation to decay in the hollows. In the well-known
words of Gibbon, 'the Campagna of Rome was speedily reduced to the
state of a dreary wilderness in which the land is barren, the waters
are impure and the air is infectious.' Fever, which probably always
found a home in various parts of the district, now stalked everywhere,
until at the end of the twelfth century, when the population of the
city had fallen to no more than 35,000 souls, Pope Innocent III. could
declare that it was difficult to find there a man of forty years of age
and hardly possible to meet with one of sixty.
No one will dispute that the sole, or at least the chief, cause of
this long-continued depopulation is to be found in the prevalence of
malarious fever. Nor, since modern science has so clearly revealed
the nature and source of this decimating malady, can there be any
hesitation as to the more important steps that must be taken to
restore the region to healthfulness and fertility. Schemes are now in
contemplation to reclaim these wastes to cultivation, and to repeople
them with an industrious peasantry. While every lover of Italy will
rejoice over the successful accomplishment of such a beneficent reform,
those who have known the Campagna in the days of its desolation, and
have found in its weird loneliness and quiet beauty, in its monuments
and memories of the past, an inexpressible delight, will perhaps be
pardoned if they regretfully look back upon another of the charms of
Rome which shall then have passed away.
GLASGOW: PRINTED AT THE UNIVERSITY PRESS BY ROBERT MACLEHOSE AND CO.
LTD.
FOOTNOTE:
[103] _International Quarterly_, June 1904.
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|Obvious typographic errors have been corrected. |
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