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 Centre-East
of Sardinia
The centre-east of Sardinia covers an area which
demonstrates, through its lithology, structure,
evolutionary characteristics and morphological
features (i.e. its countryside), the Palaeozoic and
Mesozoic history of Sardinia:
1) A base made up of rocks from the Palaeozoic era,
reshaped and metamorphosed during the Hercynian
Orogeny and later mixed with granitoid rock during
the final stages of the orogenesis;
2) A sedimentary covering of the base, composed of
essentially carbonatic rocks from the Mesozoic era.
In a stratographic position between the base and the
cover, there are also layers of continental
sedimentary deposits from the lower Permian age
which, despite their limited extent, have notable
importance both historically, in helping to
reconstruct the geology of the area and
economically, because of the presence of coal. Above
the Mesozoic sedimentary cover, the extended layers
of cenozoic volcanic rock, so diffuse around the
west of Sardinia, are lacking here. Equally
infrequent are plio-quaternary basalts from the
Sardinia’s most recent volcanic cycle, with only
small clusters around Dorgali.The geological
peculiarity of the area, of naturalistic, economic
and scientific interest, is characterised by a
dualism between basalt/Mesozoic covers. This dualism
is quite manifest if one examines the contrasting
morphologies: harsh, almost vertical slopes in the
limestone covering; soft and modestly acclivitous
slopes in the metamorphic base rocks.This
morphological contrast is therefore only the visible
expression of the diverse lithological and
structural differences between the base and cover.
However, the discrepancies are also reflected in a
different distribution of:
1) mineral deposits 2) areas of palaeontological
interest 3) water resources. A brief description of
the two main geological features which, as seen,
shape significant amounts of the Cala Gonone area,
is therefore necessary
Geomorphological Classification
The area is a part of the mountain
structure of the Sardinian centre-east coast. Its
territories are situated at an average height of more
than 250 metres. In the entire territory of Dorgali,
which leads from the sea up to the SS. 125, the
mountains are composed of limestone, whereas in the
area of Santa Maria Navarrese and Baccu Ertili they
are made of granite and porphyry.
The whole territory is “ploughed” by
narrow and deep valleys – called “codule”, which lead
into the sea interrupting the limestone cliffs of the
coastline. The landscape is charcterized by rocks,
cliffs, deep gorges, dolines and precipices. It is
dominated by the karstic plateau of the Supramonte di
Baunei with its average height of 600/700 metres. This
wide area is crowned by the mountain tops of
Orrolotzi, Ginnircu, Nortorei, Trattasu and Narbone
towards the sea, whereas the border of the inner
valley is dominated by the peaks of Bitzicoro and
Doloscaccoro. Both of them exceed 800 metres in
height.
The territory is characterized by
different lithotypes (types of rock) from which
distinct morphologies derive: crystalline slates,
granite and porphyric stones of the ancient
crystalline substratum, jurassic limestone, basalt of
the Pleistocene era, recent floods and detritus of
Holocaen layers. Slates can be found in the valley of
the “Orientale Sarda” from about km 161 up to km 153.
From this line they extend to the east up to the
borderline between Dorgali and the village of Triei
and to the west up to Santa Maria Navarrese. Their
morphology is three-dimensional with a hydrography
carved into the rock which is due to the limited
permeability of the substratum.
The granite and porphyry stones cover
the western strip of the territory or better, the area
between Punta Selole and Punta Cocussau – from the
north to the south – and between Cuccuru Albu and
Punta Malosa – from the east to the west. Here,
especially at Marghine, the landscape presents the
typical granite morphology: the granite appears with
increased frequency on the surface where zones filled
with granite stones and slight slopes alternate.
Most of the area is characterized by
sedimentary deposits of detritus which stretch
approximately from the SS. 125 up to the sea. Here,
the jurassic limestone of the Mesozoic era, which
extends from the coast to the west, is predominant.
Therefore, the landscape is clearly characterized by a
karstic morphology,
with a large range of precipices, dolines, ovals and
steep faces, both near the sea and in the interior,
where the heads of the
strata are uncovered because of the complex structural
history of their formation.
At the foot of these steep slopes heaps
of gravels and shingles have formed and are still
forming; the dialect word “girove o bacu” indicates
these heaps and is one of the most spread territorial
names. In the inner areas of the surface which is
dominated by jurassic limestone effusive basalts can
be found which form the characteristic expanding
terraces of the basic rocks. Most of them are situated
in the locality “Golgo e Mesu”, where a stream of
olivinic basalts covers the valley bottom extending
for nearly 5 km and resting directly on the
organogenous limestone.
The most important hydrogeological
basins are the Rio Codula di Ilune, Codula di Sisine,
Codula de Fuili and the tributary complex of the Rio
Pramaera.
Many thanks to the agency for natural
and cultural tourism “Zente”. |
