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ARTICLE IN PRESS
36 L. Ferranti et al. / Quaternary International 145– 146 (2006) 30–54
Ligurian–Balearic and Miocene–Pliocene Tyrrhenian
sea rifting, respectively (Cherchi and Montandert,
1982; Burrus, 1984; Rossi et al., 1996; Assorgia et al.,
1997). Today, both islands appear tectonically stable
(Fig. 5a; Boschi et al., 1997).
The present-day pattern of regional deformation is
recognized through crustal seismicity and GPS velocity
fields (Fig. 5b). The earthquake focal mechanisms
record northeast–southwest extension along the axis of
the Apennine chain and northeast–southwest to north–
south contraction and transpression in several segments
of the Adriatic foreland of the Apennines, southern Alps
and Dinarids (Gasparini et al., 1985; Montone et al.,
1997). GPS velocities together with regional seismicity
(Fig. 5b) indicate that the southern part of Italy
experiences larger horizontal velocities than its northern
counterpart as both parts converge towards stable
Europe (Oldow et al., 2002; Oldow and Ferranti, 2005).
4. Data compilation
4.1. Sea-level indicators
Based on field observations, a list of the MIS 5.5
highstand markers (Table 1 and Fig. 6) was established.
The list includes seven types of markers grouped in three
classes (Table 1). Two classes are composed of depositional
and erosional/chemical indicators of the eustatic sea-level. the upper limit of the burrows a sub-horizontal line is
In addition, we introduce a third class of biological
indicators, which are destructive or constructional organ-
isms living at sea-level. According to its nature, each
marker was assessed its specific uncertainty regarding sea-
level positioning. We consider markers with definable (and
preferentially small) uncertainty as reliable.
4.1.1. Depositional indicators
4.1.1.1. Beach/lagoon transition deposit. Lagoonal de-
posits (silty and clayey sediments) frequently bear the
bivalve Cerastoderma glaucum and the gastropods
Bittium sp., Rissoa sp. and Hydrobia sp. This fauna
assemblage is characterized as ‘‘Euryhaline and Eur-
ythermal in brackish water (LEE)’’ (Peres and Picard,
1964). It indicates the mean sea-level with an uncertainty
of 2 m.
4.1.1.2. Backshore/foreshore deposit. These deposits
are typically composed of litho- and bioclasts forming
ridges and wedges, but they may be related to a
shoreline with variable uncertainty. In general, the
uncertainty for both backshore and foreshore deposits
may be 10 m if lateral facies transition or biofacies are
not established. When facies analysis allows correlation
of beach deposits with adjacent foreshore and backshore
sediments, the palaeo-sea-level position might be identi-
fied with an uncertainty of 6 m.
4.1.2. Erosional/chemical indicators
4.1.2.1. Inner margin of marine terraces. The inner
margin of a terrace indicates the position of the palaeo-
shore line. In hard rock it appears as a step between the
wave-cut platform and the former cliff. In soft rock, it is
covered by colluvial deposits and can hardly be
identified. An uncertainty of 3 m was attributed to
well-exposed inner margins and 20 m to the masked
ones, the latter being only evidenced by a knickpoint in
the topographic profile.
4.1.2.2. Marine terrace. Terraces are today usually
degraded and their inner margin is destroyed. The
maximum height of the terrace was therefore taken as
the indicator of palaeo-sea-level with an uncertainty of
20 m.
4.1.2.3. Tidal notch. The notch is a common intertidal
feature at coasts with moderate tidal range. The
maximum concavity is formed by the neap tide range
and is, thus, a precise measure of the mean sea-level
position with assigned uncertainty of 0.2 m.
4.1.3. Biological indicators
4.1.3.1. Top of lithophaga hole band. The pelecypod
Lithophaga lithophaga colonizes the first 20 m below the
sea-level of calcareous rocky coasts, but it is statistically
very frequent in the first 2 m below mean sea-level. From
defined, which is considered as a reliable marker of a
past mean sea-level position (Stiros et al., 1992),
provided that fossil specimens of L. lithophaga are
found in some of the rock-bored holes. The assigned
uncertainty on this marker is 2 m.
4.1.3.2. Dendropoma reef. One of the most valuable
indicators of sea-level are in situ bioconstructions of
some calcareous algae (Lithophyllum lichenoides, Neo-
goniolithon notarisii) living alone or in symbiosis with
the gastropod vermetids Dendropoma petraeum (Anto-
nioli et al., 1999a). The lower limit of the bioconstruc-
tion corresponds to the mean low tide level (Laborel and
Laborel Deguen, 1994). The narrow zonation of these
organisms yields an indication of sea-level with an
uncertainty of 0.2 m. Unfortunately, Dendropoma
markers, although frequent in present-day reefs, are
rare as fossil reefs due to their fragile nature and are
only known from sheltered caves of Sicily (Antonioli
et al., this issue).
4.2. The uncertainty of sea-level constraints
The uncertainty of sea-level positioning is constrained
by the precision with which the position of the indicator
with respect to the palaeo-sea-level is determined and
precision of the age of the indicator.