Walker - 1967 - A geography of Italy

THE MOUNTAIN ZONE. The chestnut horizon which extends up to about 950m in
Lazio and 1350m on the slopes o f Etna, may be regarded as transitional to the
mountain zone proper. The chestnut’s preference for crystalhne soils has already
been noted and it is best exemplified in the slopes o f Monte Amiata, Monte
Cimino, Monte Vulture and the Sila plateau. At full stature its fresh green leaves
filtering light into a moist imdergrowth o f ferns and bracken make a welcome
change from the duller hues and tinder-dry fitter o f the Mediterranean woods
below. But the Apennine mountain tree par excellence is the beech; in central
Italy it extends from about 900 to about 1800m, that is practically to the limit of
trees. Its very dense leaf cover discourages tmdergrowth and its only competitor
is the white fir {Abies alba), which has suffered even more than the beech at the
hands o f Man. Where conifers are found in any numbers in the Apennines they
are usually the fruit o f re-afforestation. The beech occurs on a variety o f soils; it
is regarded as a climax, and although it has been so sadly reduced in area and
quality, in the absence o f Man it would recapture all but the highest slopes. In
fact, the upper moimtain forest has been under continuous attack from transhumant
flocks and it has been widely replaced by pastures, constantly overgrazed
and rarely worth cutting for hay. The hardy shrubs and stunted trees,
which are the pioneer fringe o f the Alpine forests, are almost entirely absent in
the Apemiines.
PART I I : SOME P H YSIC A L GEOGRAPHY
ST R U C T U R E
The geographer’s interest in structure, a term which will be very liberally
interpreted, lies mainly in its profound influence on Alan’s physical environment.
Since the relationship between this environment and the human response
to it is often best discussed in its regional setting, only the broader structural
aspects will be treated here.
Ancient shields and their associated fold moimtain systems are the basic
elements o f Europe’s anatomy. Unless there is justification for the view, now
less generally accepted, that a foundered crustal block underlies the Tyrrhenian,
the former have no part in the build of Italy, but at least three mountain-building
systems are represented. O f the Caledonian folding the main evidence lies in the
Cambrian beds of Iglesiente, but sizeable fragments o f the Hercynian system are
exposed within the Italian Alps, notably in the massifs o f Argentera, M t Blanc
and Monte Rosa, as well as in the Cam ic Alps; they have their counterparts
beyond the frontier in the M t Pelvoux, Belledonne and Aar-St Gotthard massifs.
It was against and over these Hercynian Palaeo-Alps that the Alpine folds
proper were later to be thrust. The Hercynian movements were accompanied by
intrusions o f granite and extrusions o f lava, the latter being best represented in
the porphyries o f Besimauda (Ligurian Alps), Valsesia, Lugano and the upper
Adige. Outside the Alps the crystalline blocks o f Corsica-Sardinia and Calabria-
Peloritani massifs are also regarded as Hercynian.
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