Raised coastal terraces along the Ionian Sea coast of northern Calabria, Italy, suggest space and time variability of tectonic uplift rates

Quaternary International 206 (2009) 78–101

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Raised coastal terraces along the Ionian Sea coast of northern Calabria, Italy, suggest space and time variability of tectonic uplift rates E. Santoro a, M.E. Mazzella b, L. Ferranti b, *, A. Randisi c, E. Napolitano b, S. Rittner d, U. Radtke d a

` di Catania, Italy Dipartimento di Scienze Geologiche, Universita ` di Napoli, Italy Dipartimento di Scienze della Terra, Universita c Istituto per l’Ambiente Marino Costiero, CNR, Napoli, Italy d ¨ t zu Ko ¨ln, Germany Geographisches Institut, Universita b

a r t i c l e i n f o

a b s t r a c t

Article history: Available online 18 October 2008

A detailed study of uplifted Middle–Late Pleistocene marine terraces on the eastern side of northern Calabria, southern Italy, provides insights into the temporal and spatial scale variability of vertical displacement rates over a time span of w400 ka. Calabria is located in the frontal orogen of southern Italy above the westerly-plunging Ionian slab, and a combination of lithospheric, crustal, and surface processes concurred to rapid Late Quaternary uplift. Eleven terrace orders and a raised Holocene beach were mapped up to w480 m a.s.l., and were correlated between the coastal slopes of Pollino and Sila mountain ranges across the Sibari Plain, facing the Ionian Sea side of northeastern Calabria. Precise corrections were applied to the measured shoreline angles in order to account for uncertainty in measurement, erosion of marine deposits, recent debris shedding, and bathymetric range of markers. Radiometric (ESR and 14C) dating of shells provides a crono-stratigraphic scheme, although many samples were found to be resedimented in younger terraces. Terrace T4, whose inner margin stands at elevations of 94–130 m, is assigned to MIS 5.5 (w124 ka), based on new ESR dating and previous amino acid racemization estimations. The underlying terraces T3, T2 and T1 are attributed to MIS 5.3 (w100 ka), 5.1 (w80 ka) and 3 (w60 ka), as inferred from their relative position supplemented by ESR and 14C age determinations. The age of higher terraces is poorly constrained, but conceivably is tracked back to MIS 11 (w400 ka). The reconstructed depositional sequence of terraces attributed to MIS 5.5 and 7 reveals two regressive marine cycles separated by an alluvial fanglomerate, which, given the steady uplift regime, points to minor sub-orbital sea-level changes during interstadial highstands. Based on the terrace chronology, uplift in the last w400 ka occurred at an average rate of 1 mm/a, but was characterized by the alternation of more rapid (up to w3.5 mm/a) and slower (down to w0.5 mm/a) periods of displacement. Spatial variability in uplift rates is recorded by the deformation profile of terraces parallel to the coast, which document the growth of local fold structures. Ó 2008 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction A growing body of evidence worldwide is highlighting the paramount importance of precise and accurate determination of intermediate-scale displacement rates in order to bridge the gap between tectonic events occurring at geologic time-scales and directly observable deformation and related morphological-sedimentary processes. Depending on the specific tectonic setting, intermediate time-scales vary greatly, but they are typically within the ten to hundreds ka range. At coastal regions, determination of

* Corresponding author. E-mail address: [email protected] (L. Ferranti). 1040-6182/$ – see front matter Ó 2008 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2008.10.003

intermediate scale vertical displacement rates is afforded by ancient geomorphologic markers tied to the coeval sea-level (Bloom et al., 1974; Merritt and Bull, 1989; Muhs et al., 1990; Lajoie, 1986; Lajoie et al., 1991). These studies are pivotal in order to address complex issues related to deformation mechanisms, such us the well-known debate over constancy versus episodic nature of deformation (e.g. Friedrich et al., 2003; Ferranti et al., 2007; Oldow and Singleton, 2008). Toward this end, a detailed reconstruction of relative sea-level changes, which takes into account the separate contribution of eustatic, tectonic and sedimentary processes, is mandatory. Such reconstruction is, however, notoriously difficult mainly due to a limited accuracy in uncertainty stipulation for long- and midterm sea-level markers. Beside the intrinsic difficulty in recognition

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and dating of markers (Muhs et al., 1990; Stirling et al., 1998; Thompson and Goldstein, 2005), which strongly impacts the related eustatic corrections, several factors including paleobathymetry, measurement errors, and erosional/sedimentary reshaping contribute to downgrade the uncertainty stipulation. Although recognized as a major pitfall in relative sea-level changes determination (Merritt and Bull, 1989; Pirazzoli, 1993; Caputo, 2007), many of the above factors are addressed with difficulty in research papers. The present study uses markers of past shorelines found along the northeastern Calabria coastline in southern Italy as a means to retrieve vertical displacement rates from the Middle Pleistocene to the present. Southern Italy is an outstanding example of an active orogen (Fig. 1), and the northern Calabria sector offers an unprecedented opportunity to characterize medium-term relative sea-level

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changes and tectonic rates for a number of reasons: 1) the youthfulness of the orogenic processes is reflected in the recent and current deformation field (e.g. Ferranti et al., 2008) and offers a means to interpret the reconstructed sea-level history; 2) uplift rates are among the highest in the Mediterranean Sea region (Westaway, 1993; Antonioli et al., 2006; Ferranti et al., 2006, 2007; Westaway and Bridgland, 2007); 3) markers of Quaternary shorelines, mostly marine terraces, notch and wave-cut platforms, are well-developed and allow an excellent chrono-stratigraphy to be established; thus, provided that sound age-control points are obtained, age uncertainties are a secondary issue; 4) degradation rates are moderate and markers can be readily identified; 5) tidal ranges are, and arguably were, limited, which, coupled to a welldeveloped tide network, renders datum reference uncertainty to be suitably stipulated.

Fig. 1. Generalized tectonic map of the Southern Apennines frontal zone in Calabria–Basilicata. Grey arrows show the vertical displacement rate (mm/a) of the MIS 5.5 marine terrace (after Ferranti et al., 2006). Fault: CRF, (Corigliano-Rossano fault); PCF, Pollino-Castrovillari fault (after Catalano et al., 1993; Monaco et al., 1998); AL Avena–Lauropoli fault. Inset: tectonic setting of southern Italy, showing the Benioff-Wadati zone of the Ionian slab (lines contoured after Giardini and Velona`, 1988) and the margins of the Ionian oceanic plate (after Catalano et al., 2001).

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The studied coastal region underlies the frontal thrust belt of southern Italy, which since the Middle Pleistocene was uplifted at average rates which peaked at over w1 mm/a (Fig. 1; Cucci and Cinti, 1998; Ferranti et al., 2006). This rapid vertical displacement is commonly attributed to deep-seated processes in the slab underlying the Calabrian arc (Westaway, 1993; Cucci and Cinti, 1998; Bordoni and Valensise, 1998), although a prominent role of erosionally triggered lower-crustal flow is suspected (Westaway and Bridgland, 2007). At a more focused scale, within the region of interest, a local contribution to uplift was provided by growth of transpressional structures (Ferranti et al., in press). The interplay between uplift and eustatic cycles has produced a flight of coastal terraces raised at tens to several hundred meters of elevation, which are exposed within deep gorges entrenched by seasonal streams into the rapidly uplifting bedrock. Notwithstanding the fluvial dissection, a good correlation between laterally severed terrace remnants is afforded by distinctive sedimentary packages built owing to the high clastic supply from the rising coast. Among these terrace orders, of particular relevance is the one attributed to the Last Interglacial, equated to the Marine Isotope Sub-Stage (MIS) 5.5 and dated at w124 ka, which provides the best constrain to evaluate the regional uplift pattern (Ferranti et al., 2006). During the MIS 5.5, a warm faunal assemblage known as ‘‘senegalaise fauna’’ (Gignoux, 1913), and mainly represented by molluscs (i.e.: Strombus bubonius, Conus testudinarius, Cardyta calyculata senegalensis, Hyotissa hyotis) progressively colonized the Mediterranean shelves and is a distinctive attribute of the coeval marine sequence. In northeastern Calabria, however, development and/or preservation this faunal assemblage is hindered by the huge clastic supply. The regional elevation of the MIS 5.5 marker elsewhere in southern Italy and eastern Sicily indicates an average regional uplift at w1 mm/a since the Last Interglacial (Fig. 1), a finding extended back to the Middle Pleistocene by some workers (Westaway, 1993; Bordoni and Valensise, 1998). This pattern is typically taken to indicate the constancy of the uplift rate (Cucci and Cinti, 1998), but few direct geo-chronological constraints exist to date in the studied region, and thus the position of the 124 ka terrace is debated (e.g. Carobene, 2003; Cucci, 2004). Based on detailed mapping and sedimentary facies analysis, on accurate reconstructions of tectonically controlled lateral changes in paleo-shoreline geometry, and on reasonable geochronologic constraints coming from published and new dating, the coast of northeastern Calabria experienced temporally non-constant and spatially non-homogeneous uplift rates. Although total uplift was dominated by a regional signal, lateral variations in displacement were controlled by growing folds. Not only constancy of vertical displacement was thus ineffective on the temporal scale, but uplift rates changed also across laterally adjacent domains in response to the control exerted by local tectonic structures. Besides this general finding, the analysis outlines the importance of a joint appraisal of facies architecture and tectonic control in coastal tectonic studies. During sea-level changes that are more rapid than tectonic rates, the eustatic signal was predominant as recorded in the stratigraphic architecture of highstand sequences, which included two transgressive sequences during the late Pleistocene sea-level cycles. 2. Regional background The Ionian Sea coast of northeastern Calabria is located in the frontal sector of the Apennines thrust belt, between the Pliocene– Pleistocene frontal thrust and the hinterland sector experiencing coeval extension (Fig. 1). Growth of the southern Apennines and Calabrian orogen occurred during Neogene north-westerly subduction and easterly roll-back of the Adriatic–Ionian slab

(Gueguen et al., 1998; Faccenna et al., 2001). Deformation progressed to the northeast and east toward the Apulia–Adriatic and the Ionian Sea foreland (Fig. 1), and involved Mesozoic and Cenozoic basinal and carbonate platform rocks (Monaco et al., 1998). Motion of the frontal thrust belt in the Southern Apennines ceased during Early Pleistocene, but ongoing contraction and transpression occurred at deeper structural levels during the Quaternary (Van Dijk et al., 2000; Bertotti et al., 2001; Ferranti and Oldow, 2005). Shortening is probably occurring today in the coastal area and in the Ionian offshore as documented by geodetic GPS velocities and marine geophysical data (Ferranti et al., 2008, in press; Del Ben et al., 2008). The transition between shallow and deep-seated shortening was accompanied by rapid uplift of Calabria since the Middle Pleistocene. This recent uplift is spectacularly documented by flights of coastal terraces and wave-cut platforms displaced to hundreds of meters above the present sea-level (e.g. Westaway, 1993; Miyauchi et al., 1994). Uplift is viewed as an isostatic (Westaway, 1993; Wortel and Spakman, 2000) or dynamic (Gvirtzman and Nur, 2001) response to removal of a high-density deep root, or, alternatively, as arising from stalling of slab roll-back and trapping of Calabria between the buoyant continental landmasses in Apulia and southern Sicily (Catalano et al., 2004; Goes et al., 2004). Recent work has highlighted the thermal response to sediment load in promoting crustal uplift through lower-crustal flow directed beneath the on-land region of prevailing erosion, and is supported by the temporal coincidence between the establishment of the w100 ka Milankovitch forcing and onset of Calabrian uplift (Westaway and Bridgland, 2007). A local tectonic component is also embedded within the uplift budget. Whereas uplift in southern Calabria and eastern Sicily is associated to extensional faulting (Monaco and Tortorici, 2000; Ferranti et al., 2007), regional analysis in the northern Ionian and Adriatic coast indicate that a component of large-scale folding rooted at deep crustal levels may have contributed to uplift (Bertotti et al., 2001; Ferranti and Oldow, 2005). 3. Geological setting of northeastern Calabria Northeastern Calabria is occupied by the wide Sibari coastal plain intervening between the Pollino and Sila mountain ranges to the north and south, respectively (Fig. 1). In this region, the geological architecture consists of Paleozoic–Cenozoic crystalline and sedimentary rocks of the Calabrid units which outcrop to the south in the Sila massif, and of Mesozoic–Cenozoic sedimentary rocks of the Apenninic platform and of the Ligurid and Sicilid basins, which are found in the Pollino mountain range to the north (Fig. 1). Following Late Oligocene–Early Pliocene assembly of these tectonic units (Bonardi et al., 2001), the area was filled by several hundred meters of latest Pliocene to early Pleistocene marine clay, sand, and fanglomerate (Colella et al., 1987; Colella, 1988; Colella and Cappadona, 1988), covered by Middle Pleistocene to Holocene marine and continental deposits arranged in a stepped flight of terraces (Cucci and Cinti, 1998; Carobene, 2003; Cucci, 2004). The separation between the Sibari Plain and the bordering mountain ranges was accommodated by Pliocene–Quaternary displacement on high-angle faults (Ghisetti and Vezzani, 1982; Catalano et al., 1993; Cinti et al., 1997; Van Dijk et al., 2000; Tansi et al., 2007), but their relation with the Middle–Late Pleistocene terraces is poorly established. The flight of Middle–Late Pleistocene terraces mimics the present coastal embayment of the Sibari Plain and Pollino–Sila Ranges (Fig. 2), and was carved in pre-Pliocene bedrock and Early Pleistocene clay and sand. Following decades of detailed geomorphologic and sedimentologic analysis mostly centered north of Pollino (Dai Pra and Hearty, 1988; Amato et al., 1997; Amato, 2000), uplifted marine terraces in the region were

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Fig. 2. Generalized morphological map of the Middle Pleistocene–Holocene marine terraces on the Ionian coast of northern Calabria, showing the trace of inner edges for individual orders. Location of maps in Fig. 3a–f is shown in six inset boxes.

studied by Cucci and Cinti (1998), who mapped 7 terraces along the eastern side of the Pollino Range between 12 and 420 m. Based on lateral correlation with dated terraces to the north, the Pollino terraces were assigned to as many Middle Pleistocene (w600 ka) to Holocene highstands of the global sea-level curve. Uplift of the terraces at rates increasing to the south from w0.7 to w1 mm/a was attributed to a regional, deep source (Westaway, 1993). North of the Pollino Range in the Bradano fore-trough basin of the Apennines, the pattern of uplift decreases to a minimum at the northern shore

of the Taranto Gulf (Fig. 1). Mapping of terraces was extended to the south across the Sibari Plain by Cucci (2004), who found 5 strandlines at elevations between 60 and 650 m. Minor differential displacement of the terrace flights was attributed by Cucci and Cinti (1998) and Cucci (2004) to footwall uplift caused by slip on the Pollino–Castrovillari fault (Fig. 1). Conversely, no evidence of motion was found on the AvenaLauropoli and Corigliano–Rossano faults east of Pollino and in northern Sila, respectively. Bentivenga et al. (2004), and Ferranti

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et al. (in press), instead, showed that the Middle Pleistocene terraced sedimentary body is cut and displaced toward the Ionian Sea by shallow-rooted, listric extensional faults of the Avena– Lauropoli system, whose development was related to large-scale gravitational processes triggered by uplift and eastward-tilting. Using the elevation distribution of the terrace inner margin, Ferranti et al. (in press) have shown that the coast-parallel profile of the ancient shorelines record small-wavelength and -amplitude undulations superposed to the regional uplift. The local-scale, but pervasive undulations in the deformation profile of marine terraces were attributed to shallow-crustal folds related to a still active transpressional field, which is jointly recorded by fluvial anomalies, marine geological data, local seismicity and broad geodetic networks (Ferranti et al., 2008). As an extension of that work, a detailed mapping of the inner margins of past shorelines will be presented in the present paper. Only on the lowest terraces it was possible to retrieve marine deposits few tens of meters thick (Cucci, 2004). The upper terraces are, instead, stripped of their sedimentary cover. Based on amino acid racemization on shells, Cucci (2004) assigned the second terrace from the bottom (T2) to the MIS 5.5 at 124 ka, resulting in an uplift rate of w1 mm/a. This terrace is by far the widest within the terrace flight, and this appears consistent with observation elsewhere in the central Mediterranean Sea (Ferranti et al., 2006). The terrace rises southward from w110 to w130 m along the Pollino coast. In the Sibari Plain, the terrace is placed at a w20 m lower elevation, but in Sila it rises again to w130 m (Randisi, 2007; Ferranti et al., in press). In Sila, instead, Carobene (2003) attributed a terraced deposit at 68 m to MIS 5.5, but chronological constraints were poor. In this area, Carobene (2003) presented a detailed facies analysis of a series of stepped terraces, and identified complete highstand depositional sequences, including the transgressional and aggradational part of the cycle, for two individual terrace orders. 4. Methods A number of factors have contributed to fostering different interpretations, within published papers, of the coastal terrace flight along the Ionian coast of northern Calabria, namely regarding the number of orders, chronological attribution, and related uplift rates. Such differences chiefly arise from ambiguities in defining the spatial extent and lateral correlation of terraces, which in turn depends on the variable morphology of the same terrace order when different bedrock lithologies are involved, and from a laterally uneven coastline paleo-morphology (Amato et al., 1997). The tectonic effects of spatially variable uplift rates, with a regional tilt down to the northeast and the local development of fold-related lows and culminations (Ferranti et al., 2006, in press) also conspire to prevent a straight elevation correlation. Thus in an attempt of deciphering the relative sea-level history in the area, a multidisciplinary approach was used, involving a geomorphic, sedimentological and tectonic analysis of terraces, in order to derive the nominal paleo-shorelines and compute the related uncertainties with the best accuracy (Bull, 1985; Ota, 1986; Muhs et al., 1990; Lajoie et al., 1991). 4.1. Terrace mapping Terrace exposures are remnants of once continuous depositional systems, which experienced incision by ephemeral streams and reduction in size by hillslope wasting during uplift. A detailed lateral correlation of individual remnants was performed through aereophotograph analysis (1:17000 scale) and field survey (1:10.000 and 1:5000 scale topo maps and orthophotos, respectively). Geomorphic correlation was constrained along a broad elevation range by the

areal dimension, the slope of the ancient abrasion platform and cliffs, and the degree of dissection of terrace remnants (Table 1). Careful measurement of the main geomorphic markers (inner edges, risers, width of the abrasion platform) was accompanied by a detailed sedimentological and facies analysis of terraced deposits, when present. Particular attention was devoted, as a means to improve correlation, to the identification and characterization of sedimentary cycles, both transgressive and regressive, within individual highstand depositional sequences. Uncertainty in positioning stems from a combination of accuracy in marker identification and precision in measurement. The maps used to trace markers have 10-m and locally 5-m contours. Thus, uncertainty in elevation estimate is probably within 10 m. GPS and altimeters used to retrieve spot location of inner edges and other markers have a similar 10 m uncertainty. Terraces were mapped from the present sea-level up to an elevation of w480 m. Higher remnants were recognized up to w650 m (Cucci, 2004), but due to the very scattered distribution and difficulty in correlation, they were discarded from further analysis. Mapped terraced remnants were framed in the context of the structural evolution, including syn- and post-depositional development of anticlines and synclines with axes striking roughly wnormal to the coastline, and of normal faults displacing toward the coastline (Ferranti et al., in press). A correction for tectonic offset (mainly for normal fault displacement) was thus taken into account for terrace correlation.

4.2. Nominal paleo-shoreline elevation Toward calculation of the nominal paleo-shoreline for individual terrace orders, additional corrections and uncertainty stipulations were sequentially applied to the observed marker elevations. Given the morphological setting, the most commonly used marker is represented by the inner margin or shoreline angle between the ancient terrace and related sea-cliff. A first uncertainty involves difficulty in marker identification due to post-emergence degradation: this error is estimated in very few meters. A further ambiguity is caused by post-emergence continental cover on the terrace. The thickness of alluvial and colluvial sediments shedding the terrace inner margins is highly variable but is commonly within 10 m. Unlike previous generalized corrections (Amato et al., 1997; Cucci and Cinti, 1998), the estimation for this uncertainty was computed on a site-by-site basis, using natural cuts or boreholes. This allowed Table 1 Main morphologic and sedimentary parameters of terraces T0–T11 at the Pollino and Sila coasts. Terrace order

Inner margin elevation (m)

Average width (m)

Average slope (degree)

Maximum dep. thickness (m)

P

S

P

S

P

S

P

S

T0 T1 T2 T3 T4 T5 T6

5–11 11–24 33–64 56–96 94–123 120–185 180–225

 17 45–70 75–93 103–130 130–165 158–196

173 179 64 200 450.5 419.5 188.5

  200 617 807 650 633

1.2 0.7 1.5 1.7 2.1 1.9 2

  1.1 1.6 2 1.7 1.8

   10 16 18 8

T7 T8 T9 T10 T11

252–292 303–340 363–415 398–448 437–486

198–230 260–284 343–365 385–393 440–445

138.5 209 143 186 344

427 390 368 230 400

2.7 3.1 3.6 2.8 2.4

2.4 3.3 3.5 3.6 2

 (14a) 13 11 36 23 14 (32a) 2    

P ¼ Pollino coast. S ¼ Sila coast. a Borehole interpretation.

    

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more accurate determination of the erosional or depositional inner margin elevation. Additionally, the geometry of the depositional sequence representing the late transgressive and highstand system tracts during individual interglacial (sub-) stages was evaluated. The highest position reached by the sea during an Interglacial is indicated by the top of foreshore sediments. This position could coincide, but more likely would be offset relative to the morphological inner margin or to the innermost on-lap of the coastal depositional sequence, which involves a broad range of sub-environment, including the coastal alluvial plain and small-scale Gilbert-type delta fan. Thus, a 3-D analysis of sequence evolution was performed for the youngest terraces, whose marine sediments were not stripped off by erosion, to search for the uppermost position reached by the foreshore deposit. The elevation of this contact, when available, represents a more accurate estimator of the paleo-shoreline than the morphological inner margin for computing uplift rates. Uncertainty in the identification of the internal relations within the sedimentary body results from later degradation. Therefore, type sections for each of the young terrace orders were measured as completely as possible, against which incomplete sections elsewhere were compared for the due correction estimation. The largest uncertainty in nominal paleo-shoreline elevation stems from the choice of the appropriate bathymetric correction for different markers (constructional, erosional), which must be evaluated at individual locations. The coastal deposits associated to the terraces typically form ridges and wedges, which can be related to a shoreline with variable uncertainty. In general, the uncertainty for both backshore and foreshore deposits may be 5 m if lateral facies transition was not established. When facies analysis allowed correlating beach deposits with adjacent foreshore and/or backshore sediments the paleo-sea-level was estimated to be within 2 m. In the case of well-exposed erosional inner margins, uncertainty was estimated to be þ10 m. Where inner margins for terrace remnants could not be identified, the maximum height of the terrace was taken as the paleo-sea-level indicator with an uncertainty of þ20 m. 5. Morphology and sedimentology of coastal terraces Eleven terrace orders, not including the Holocene beach, have been distinguished between w10 and w480 m a.s.l., and were correlated between the Pollino and Sila mountain ranges across the Sibari Plain (Fig. 2). At different locales, the terraces have different morphology and sedimentary facies depending mainly from the local physiographic and lithologic setting. In the north, the terraces are carved within Oligocene–Miocene basinal limestone and sandstones, and locally in Late Pliocene–Early Pleistocene clay and sand (Fig. 1) once filling the Apennines foredeep and satellite basins. In contrast, in the south, the terraces are mostly carved within the Pliocene–Pleistocene soft sediments, and only locally within Mesozoic hard basinal rocks covering the Calabrid crystalline basement. Terraces at the Sila coast are typically wtwice the width of the homologous orders on the Pollino coast (Fig. 2 and Table 1), probably reflecting larger abrasion processes in the widespread clay found on the Sila coast. These w1 km or more thick claystone (known as ‘‘Subapennine’’ clays) represents the youngest sedimentary unit predating onset of uplift recorded by the terrace flight (Lanzafame and Tortorici, 1981). Elsewhere in northern Calabria and eastern Basilicata (Fig. 1, inset), the claystone has an Early to Early Middle Pleistocene age (Ciaranfi et al., 1996; Pieri et al., 1996; Patacca and Scandone, 2001; Massari et al., 2002). Biostratigraphical analysis carried at the University of Naples on samples immediately subjacing the younger terraces on the eastern side of Pollino confirmed a latest Early Pleistocene– earliest Middle Pleistocene age (Esposito, pers. comm.)

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In the following section dealing with the field description of the terraces, the measured elevation of the inner margin or shoreline angle, rounded to the nearest 5 m, will be given. In a following section, this elevation will be corrected for stipulation of the nominal paleo-shoreline elevation. In addition to the inner margin elevation, we computed the average width and slope for terrace orders at the Pollino and Sila coast. The width was computed as the planimetric distance between the inner and outer margin as drawn on field maps and on aerial photos. The slope was formally computed by removing the estimated thickness of the recent continental cover shedding individual terraces. This correction yielded the top surface of the depositional sequence, which is assumed to adequately represent the slope of the basal unconformity. Finally, the schematic arrangement of the depositional architecture was drawn for most of the wLate Pleistocene terraces and mostly relied on detailed observations carried out at the Pollino coast; thus these schemes are tailored chiefly for that stretch of coast. 5.1. Terraces T7–T11 The highest terraces (T7–T11) mapped in this study, with inner margin elevation ranging from w200 to w480 m (Table 1), are reduced to small-sized remnants, strongly disarticulated by erosion and incision (Fig. 3a–f). The terrace deposits have been almost totally stripped off or might rest beneath a thick alluvial and colluvial cover, and thus only a morphologic correlation was possible. Only above terrace T7 between the Saraceno and Raganello streams (Fig. 3b), patches of marine deposits are preserved and include few meters of silt and Ostrea-bearing sand. On the Sila hillslope, around Terranova village, T7 includes sand with large coral heads of Cladocora caespitosa (Fig. 9a). Because of these limitations, the width and slope of the abrasion platform, and subordinately the elevation range of individual remnants, have been used to perform the lateral correlation. At the Pollino coast, remnants of terraces T7–T11 forms bevelled strips along ridges or are found at ridge-tops at a maximum elevation of w280, w340 w400, w450 and w480 m, respectively (Fig. 3a–b). Given their location, the inner parts of these higher terraces do not line up and thus correlation of inner margins suffers of large inaccuracy. Besides, a w40 m variability in inner margin elevation for the same terrace order is found moving along the coast (Table 1). The reconstructed mean elevation of all these high terraces appears to drop down of few tens of meters at the Sila slope. Here, the terraces are mapped at a maximum elevation of w230, w300, w350, w390 and w440 (Fig. 3e–f), consistently w50 m lower than in the north. The average width of terrace remnants is commonly 150–200 m at the Pollino coast, but at the Sila coast is twice this value, with the exception of T11, which has a 400 m width but might encompass more than a single order (Table 1). In contrast, the average slope of individual T7–T10 terraces is similar across both sides of the plain, ranging between 2.5 and 3.5 (Table 1). T11 has a lesser slope of 2–2.5 , but this might be due to the fact that the remnants sample more offshore-located parts of the terraces rather than the steeper near-cliff sector. 5.2. Terrace T6 Compared to the higher terraces, remnants attributed to T6 are more regularly distributed along the Pollino and Sila hillslope (Fig. 2). In the north, T6 is well preserved north of the Avena stream, with inner margin at w220 m, and hosts an up to w15 m thick succession along the outer margin or riser. A composite type-section (Fig. 4a, location in Fig. 3a) includes, above a lag conglomerate, massive fine sand grading to a pebble conglomerate with laminated sand intercalations. These deposits are attributed to a beach

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Fig. 3. Detailed morphological maps of the Middle Pleistocene–Holocene marine terraces in northeast Calabria (location in Fig. 2), showing the trace of the inner edges with spot location of elevation (in m). (a), (b) and (c): Pollino hillslope; (d), (e) and (f): Sila hillslope. Topographic base in Fig. 3a was extracted by a 40  40 Digital Terrain Model; base in Fig. 3b–f is taken from the 1:25.000 scale map of the Istituto Geografico Militare Italiano. Local outcrops of normal faults are indicated with barbed thick lines. Circled numbers in (a) locate outcrops used for the reconstructions of depositional sequences shown in Figs. 5, 7 and 10. Box with figure label locates the stratigraphic column shown in Fig. 4a–d. Numbers within rhombs corresponds to dated fossil specimens listed in Table 2. Eyes refer to site and visual angle of photos shown in Figs. 6, 8 and 9. Schematic sections show the main morphological features. Stratigraphic details from boreholes analysis are shown in Fig. 3a–b (boreholes S1, S2 and S4).

environment, and are abruptly surmounted by few meters of alluvial or fan conglomerate. South of the Avena and till the Saraceno stream, remnants of T6 have a far lesser extension and a lower elevation of the inner

margin at w200 m, with no deposit preserved (Fig. 3a). Further south between the Saraceno and Raganello streams, the inner margin of T6 rises again to w240 m (Fig. 3b), to fall abruptly to w225 m or less between the Raganello and Coscile stream (Fig. 3c).

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Fig. 3. (continued).

This elevation decreases smoothly between the Coscile and Crati rivers down to w160 m (Fig. 3d), but further south it climbs up again to w170–195 m east of the Crati (Fig. 3e). Finally, it drops down again to w165 m east of the Coriglianeto stream (Fig. 3f). Analysis of boreholes at Villapiana village on the southern slope of Pollino provides a better stratigraphic understanding for terrace T6. The w30 m thick succession recorded in the borehole includes, below a 20–30 m thick conglomerate of probable alluvial origin, meter-scale intercalations of sand and conglomerate attributed to T6 (section A–B in Fig. 3b). In this area, between the Saraceno and Raganello streams, the sedimentary layering dip landward in response to tilting and extensional displacement along the Avena– Lauropoli fault, which locally results in duplication of the terrace (Fig. 3b–c). On the Sila slope, terrace T6 is three-times wider than in the north, but less than 10 m of marine deposit are preserved on it. This larger width is accompanied by a significant lesser slope (Table 1), possibly arising by the substantial size of this terrace in the south.

5.3. Terrace T5 Along the Pollino slope, terrace T5 is differently developed or preserved north and south of the Avena stream. In the north, the inner margin of T5 lies at elevations of between w140 and w170 m, with the highest values found in the northern part of the coast (Fig. 3a). The terraced surfaces have a rather homogeneous size with a mean width of 400 m (Table 1). Here, the deposit has a roughly constant thickness between w10 and 20 m. Excellent exposures allowed reconstruction of the geometrical arrangement of a depositional sequence (Fig. 5). The lower part is a w6 m thick lag conglomerate passing to a pebble conglomerate which homogenously floors the sequence. This section is followed by a w12 m thick prograding wedge including, moving from landward to seaward, a beach conglomerate (Fig. 6b), foreshore and upper shoreface sand (Fig. 6a), and lower shoreface sand. A foreset fanglomerate blankets the beach sequence (Figs. 5 and 6c). In contrast, in the southern part of this coast between the Avena and Saraceno streams, T5 is strongly eroded and locally reduced to

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Fig. 3. (continued).

narrow ridge-tops underlain by the lower Pleistocene claystone. Here, sand and conglomerate associated to T5 have a limited thickness of w5 m. In the southern side of the Sibari Plain, terraced surfaces attribute to T5 have fairly homogeneous inner margin elevations ranging between w130 and 165 m, again lower than in the north, but the width of the terrace is comparable (Table 1). Like in the north, the depositional sequence has a w20 m thickness and includes, from bottom to top, a conglomerate, few meters of a fossiliferous sand,

and a younger beach conglomerate capped by a fanglomerate (Fig. 4b). As T6, also T5 is wider than in the north, of a factor of two. Its slope is, however, lesser than in the north (Table 1). 5.4. Terrace T4 As for T5, terrace T4 remnants at the Pollino coastal slope are fairly homogeneous in size with a mean width of 450 m (Table 1). The inner margin is traced at an elevation ranging from w95 to

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Fig. 3. (continued).

w125 m, and reaches the highest value in the sectors centered on the Pagliara and Raganello streams (Fig. 3a–b). The depositional sequence associated to the terrace is well mapped over the area with a maximum thickness of w35 m (Table 1), although only limited exposures of T4 deposits are preserved in the sectors of larger uplift. When compared to T5, T4 displays larger-scale interfingering between the various beach depositional environments, and is marked by a characteristic 2 m-thick layer of alluvial conglomerate within the upper-beach pebble conglomerate wedge (Figs. 7 and 8a). The regressive sequence includes, above a lag conglomerate (Fig. 8b), a 10-m thick beach conglomerate, grading seaward to a 15-m thick fossiliferous, laminated sand with intercalation of shoreline pebbles (Fig. 8b–c), in turn grading to 10 m of massive lower shoreface sand with fine planar lamination (Fig. 8d). The alluvial conglomerate blanketing the sequence is covered by a second prograding wedge of beach conglomerate and sand of limited thickness (Figs. 7 and 8a), in turn covered by a 6-m thick fanglomerate (Fig. 8e). Micropaleontological analysis of the lower shoreface sand carried out at the University of Naples has shown rare samples of Ammonia tepida (Cushman), allowing to infer an infralittoral environment (Di Donato, personal communication).

Like T6, a significant jump of the inner margin elevation from w110 to w90 m is observed between the Raganello and Coscile streams (Fig. 3c). In the southern side of the Sibari Plain, the inner margin of T4 climbs back to a background elevation of w130 m (Table 1). In this area, only a maximum of w15 m of marine deposit is preserved and includes a beach conglomerate with thin mud intercalations and few meters of fossiliferous shoreface sand, covered unconformably by a fanglomerate (Fig. 4c). Sand at the inner margin of the terrace is rich in C. caespitosa corals (Fig. 9b–c), large marine molluscs, and Serpulids. As observed for the higher terraces, the width of T4 is nearly two times (w800 m) than in the north, although the slope (w2 ) is comparable between the two sectors (Table 1). 5.5. Terrace T3 At the Pollino coast, T3 remnants are w200 m wide on average, whereas at the Sila hillslope the width is w3 times this value, as observed for the higher terraces (Table 1). Both in the south and in the north, the terrace has homogenous slope values of w1.5 (Table 1). In the north, fundamental differences are found north and

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Fig. 3. (continued).

south of the Avena and Saraceno streams, similar to what observed for the older terraces. T3 is less eroded and has better preserved deposits north rather then south of the Avena stream, and again south of the Saraceno stream (Fig. 3a–b). The inner margin ranges in elevation between w55 and 100 m (Table 1), with higher values around the Pagliara stream, where larger erosion is observed (Fig. 3a). South of the Saraceno, the inner margin climbs steadily to w85 m, but the pattern is obscured by continental cover in the central part of the Plain. Further south, at the Sila coast, T3 keeps at w90 m between the Crati and Coriglianeto streams, but drops down to below 80 m east of the Coriglianeto (Fig. 3d–f). North of the Avena stream, the terraced deposits attain a thickness of w12 m at the outer margin. The type-section is formed by a regressive–transgressive cycle which includes massive fossiliferous sand, attributed to a lower shoreface environment, unconformably covered by an alluvial conglomerate. The continental deposit is in turn surmounted by a beach pebble conglomerate (Fig. 4d). Micropaleontological analysis of the sand yielded an infralittoral benthonic association including (Di Donato, pers. com.): Ammonia beccarii (Linneo); Ammonia gaimardi (d’Orbigny); Cassidulina carinata (Silvestri), and rare samples of benthonic forams: Globigerina bulloides (d’Orbigny); Globigerinoides sacculifer (Brady); Globorotalia inflata (d’Orbigny); Turborotalita quinqueloba (Natland). The terrace at the

Sila coast exposes similar beach to foreshore, well-sorted sand with intercalation of thin (w0.5 m) pebble conglomerate layers, which becomes less coarse moving seaward. 5.6. Terrace T2 When compared to the higher terraces, T2 has a much limited width, three times less than T3 and about 1/5 of T4 , and a lesser slope of 1–1.5 , comparable to T3 but about half of T4 (Table 1). At the Pollino coast, the inner margins have elevations between w33 and 50 m which increase moving from north to south (Fig. 3a). The best exposed outcrops are found in the central sector of the coast, and allowed to reconstruct a w15 m thick depositional sequence (Fig. 10). The basal unconformity over the lower Pleistocene claystone is marked by a thin lag conglomerate with large blocks, which is covered by a regressive sequence including, moving from bottom to top, massive clayey sand and laminated medium to coarse sand (Fig. 11a). The shoreface sand exhibits increasingly more frequent fossiliferous pebbly layers in the upper part (Fig. 11b–c), where they grade laterally to a conglomerate fan showing topset and foreset geometries (Fig. 10). The sand yielded the following benthos foram association: Ammonia becarii (Linneo); Bolivina spathulata (Williamson); C. carinata (Silvestri); Cibicides lobatulus (Walzer e Jacob);

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Fig. 3. (continued).

Cibicidoides pachiderma (Rzehak); Elphidium crispum (Linneo); Globocassidulina oblonga (Reuss); Hyalinea baltica (Schroeter); Melonis barleeanum (Williamson); Sphaeroidina bulloides (d’Orbigny); Uvigerina peregrina (Cushman). This association shows a mixing between infralittoral taxa (A. beccarii and E. crispum) and circa-littoral taxa with some bathyal samples, like C. pachiderma and S. bulloides. The deeper-water taxa were probably resedimented by storm or tsunami processes in the infralittoral environment, where the shoreface sand was deposited. Due to fluvial erosion, remnants of T2 are not preserved in the central part of the Sibari Plain. Along the Sila slope, T2 inner margins are observed at elevations of between w45 and 70 m (Table 1). Thin deposit exposures are found only at the riser and include silt and fossiliferous sand.

Within the Sibari Plain, T1 is represented by a morphological step at w15 m (Guerricchio and Melidoro, 1975; Guerricchio and Ronconi, 1997). Along the Sila hillslope, T1 is not retrieved, but it might be correlated with the lowermost terrace mapped by Carobene (2003) at w25 m east of the study area. 5.8. Terrace T0 The Holocene terrace T0 is only visible at the Pollino coast and is mainly formed by loose beach pebbles with frequent (backshore?) clay intercalations. Close to the main streams, the T0 deposit shows features of a fan-delta environment with lesser sorting, larger clast size, and a marked dispersal of imbrication direction. Based on boreholes and marine sediment projection, the inner margin of this terrace is placed at 5–9 m (Table 1).

5.7. Terrace T1 6. Radiometric dating A steep paleo-cliff separates T2 from the lowermost terrace T1, which has an inner margin at 11–24 m at the Pollino coast (Fig. 3a; Table 1). The average width is w200 m, and the slope is limited to w1 (Table 1). The T1 terraced surfaces are the most continuous albeit covered by a thick continental blanket. This, together with the intense anthropic reworking, hinders observations of marine deposits. To obviate these limitations, two water boreholes located at the inner margin of T1 were used in order to retrieve an up to w15 m thick alternation of marine sand and pebble conglomerate (borehole log in Fig. 3a).

In order to add further constraints to the terrace chronology, Electron Spin Resonance (ESR) dating was applied on 16 mollusc shells from different terraces, supplemented by a 14C age determination on a sample from the lowermost terrace (Table 2). Electron spin resonance (ESR), also referred to as Electron paramagnetic resonance (EPR), can be used for dating by measuring the radiation accumulated in the mineral over time. Natural radiation, deriving from radioactive nuclides in the surrounding sediments and the mineral itself, ionizes the atoms and electrons

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Fig. 4. Composite stratigraphic logs for terraces T6 (a), T5 (b), T4 (c) and T3 (d), reconstructed on the base of different exposures. Average thickness of individual terraced deposit is shown. Locations n Fig. 3a (T6 and T3), b (T5) and c (T4). SB ¼ sequence boundary; PS ¼ progradation surface.

can move from a ground state, the so-called Valence band, to an energetically higher level, the Conduction band. Electrons that are achieving an electronically neutral state again, can be trapped charge-deficit sites, so-called defects, in the mineral. A single electron forms a weak paramagnetic centre due to its spin which is detectable by ESR spectroscopy. The relative ESR signal intensity is a measure for the relative number of free electrons and thus of its received and accumulated radiation over time. When this accumulated radiation, referred to as equivalent dose (De) is set into relation to the annual dose rate (D’), an ESR-age can be determined. In the case of mollusc shells, the date of mineralization is hereby determined.

After being etched with 2% HCl, the samples were gently grounded. Aliquots with a particle diameter of 100–200 mm were g-irradiated with a 60 Co-Source at the University Clinic of Du¨sseldorf. The applied additive dose had a rate of 1 Gy/1.34 min. ESR measurements were carried out at room temperature with a Bruker ESP 300E x-band spectrometer. The program ‘‘Fit-sim’’ by Rainer Gru¨n (version 1993) was used to determine equivalent doses (De) from relative ESR signal intensities and, subsequently, the De-Dmax plot procedure (Schellmann and Radtke, 1999) was applied to all samples. The external and internal dose rates were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) at the Geological Department, University of Cologne. Age

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Fig. 5. Geometry of terrace T5 depositional sequence at the Pollino coast. The sequence was reconstructed on the base of different observation sites (located by circled numbers in Fig. 3a). Eyes show idealized position of photographs in Fig. 6.

calculations were carried out using the program ‘‘Data IV’’ by R. Gru¨n (version 1990). Due to a commonly observed interference of the dating signal at g ¼ 2.0006 with signals at g ¼ 2.0018 and g ¼ 2.0032 (Katzenberger and Willems, 1988), the De- could only be determined for 5 samples. Overall, the ESR dating of mollusc shells could not yet achieve a geochronological differentiation of individual submaxima of an Interglacial period. This results not only from problems in Debut also in dose rate determination. Samples 1a and 1b were collected from a sandy sequence from terrace T2 at an elevation of 23 m (Fig. 3a). For samples from this outcrop, two ESR ages of 162  12 and 98  10 ka were obtained. The first age would fall within MIS 6 and is probably unreliable. The second age is linked to MIS 5, although the shell must be considered as resedimented within a younger terrace. In the same area, around Trebisacce village (Fig. 3a) Cucci (2004) attributed a terrace at w130 m elevation (T4) to the MIS 5.5 based on AAR analysis on a Glycimeris sp. shell (sample 5, Table 2). Cucci (2004) also obtained a w139 ka AAR age estimation from a Glycimeris shell (sample 6, Table 2) coming from a nearby, lower terrace, correlated to T3. As for sample 1b, sample 6 was considered resedimented by Cucci (2004). Sample 2 is a Chlamys coming from the Lauropoli area from the outer margin of terrace T4 (Fig. 3c). The ESR age of this sample (262  46 ka) could be, due to its large error, assigned to either MIS 7 or 9. The shell is resedimented. In the southern part of the study area, a ESR age of 135  20 ka, consistent with an attribution to the MIS 5, was obtained for sample 3a coming from T4 on the Sila hillslope (Fig. 3d), although an older age consistent with attribution to MIS 7 was obtained at the same site for sample 3b, which is probably resedimented.

In addition to ESR ages, a 14C AMS age determination was performed at the Poznan Radiocarbon Laboratory on a shell coming from terrace T1 in the Pollino area (sample 4). The sample comes from a conglomerate deposit located on the right bank of the Avena stream. Fragments of a Cardium sp. shell were sampled in the sandy matrix between large clasts. The w44 ka 14C calibrated age ostensibly reflects reworking of the sample, but nevertheless provides the existence of the MIS 3.1 (Table 2). Finally, samples of Cladocora from terraces T7 (Fig. 9a) and T4 (Fig. 9c) were taken for U–Th dating. Unfortunately, the high calcite content (37% and 91% for T7 and T4 samples, respectively), prevented further analysis. To summarize, the existence of deposits of stages 3, 5, 7 and possibly 9 is indicated by existing radiometric dating, although most dated samples must be considered as resedimented in younger and lower terraces. Nevertheless, the radiometric attribution of T4 to the MIS 5.5 is constrained by samples 3a and 5. 7. Discussion 7.1. Terrace chronology The chronological scheme for terrace flights in the central Mediterranean region typically relies on the elevation of the MIS 5.5 (124 ka) marker, which is mostly identified based on retrieval of key fossils of the ‘‘senegalaise fauna’’ assemblage, and specifically on the findings of S. bubonius specimens (e.g. Ferranti et al., 2006). Unfortunately, no Strombus specimen was ever collected in northern Calabria, probably because the huge clastic supply prevented the establishment of favorable hydrodynamic conditions for this warm, quiet-water mollusc. Therefore, definitive identification

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Fig. 6. Representative sedimentary facies of T5, schematic map location and section location in Figs. 3a and 5, respectively: (a) cross-laminated yellow sand; (b) intercalation of beach conglomerate and sand; (c) lens-shaped alluvial body.

of the MIS 5.5 terrace in the study area is still lacking. North of the Pollino Range, a terrace lying at w115 m elevation on the southern flank of the Bradano basin (Fig. 1), was attributed to the MIS 5.5 based on radiometric analysis (Dai Pra and Hearty, 1988; Amato et al., 1997). Although the 115 m terrace was correlated by Cucci and Cinti (1998) to the terrace standing at 160–170 m at Pollino (T5), this correlation was no longer accepted in subsequent work by Cucci (2004), who assigned a MIS 5.5 age to terrace T4 (at w110– 130 m) based on amino acid geochronology. To the south, just east of the study area on the Sila border, Carobene (2003) attributed a terraced deposit at 68 m (lined up with T2) to the MIS 5.5, but he had no radiometric age determination in support. Thus the basic step toward definition of a chronological scheme for the terraces

and for any deformation models was to place tighter constraints on the position of the Last Interglacial terrace. ESR dating (sample 3a) supplements the contention of Cucci (2004) that the terrace lying at w130 m at Trebisacce represents the MIS 5.5 highstand (Table 2; Fig. 3a, c and e). In addition to radiometric analysis, a morphological observation supplies the ground for a correct interpretation of sample ages. The MIS 5.5 age attributed to T4 is consistent with the observation, already raised by Cucci (2004), that T4 is the widest terrace (Table 1), consistent with what has been typically observed elsewhere in the central Mediterranean Sea (Ferranti et al., 2006). On the rectilinear coast of Pollino, less affected by morphologic uneveness, the width of T4 is nearly two times that of the largest younger and older terraces

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Fig. 7. Geometry of terrace T4 depositional sequence at the Pollino coast. The sequence was reconstructed on the base of different observation sites (located by circled numbers in Fig. 3a). Eyes show idealized position of photographs in Fig. 8.

(Table 1). The only exception is terrace T5, which has a width comparable to T4, and this might have elicited uncertainty in attribution (Cucci and Cinti, 1998; Cucci, 2004). It must be noted, however, that T4 has the maximum sediment thickness (up to w35 m) among the set of terraces which preserve deposits, about twice the thickness of T5 (Table 1). When T4 is accepted to represent the MIS 5.5, this observation is consistent with the prominence of the Last Interglacial. Using the elevation position of the MIS 5.5 terrace, and combining the generic Interglacial attribution indication provided by ESR and 14C ages with field observations, it is now possible to propose a chronological scheme for the whole flight (Table 3). This scheme mainly differs from Cucci (2004) work insofar he described a single terrace, with an inner margin elevations between 60 and 90 m, beneath the MIS 5.5 in the Sibari Plain, in partial correction of a previous report of three terraces subjacent the MIS 5.5 in Cucci and Cinti (1998) work on the Pollino coast. However, Cucci and Cinti (1998) attributed their fourth order to the MIS 5.5, but subsequent work by Cucci (2004) carried the implication that Cucci and Cinti (1998) third order should be the MIS 5.5. A single terrace was left between the MIS 5.5 and the lowermost, Holocene shoreline. Using an uplift rate of 1 mm/a deduced from the elevation of the MIS 5.5 shoreline in the Sibari Plain, Cucci (2004) indirectly dated his lowermost terrace to the MIS 5.3. The lack of exposure record for the younger highstands (MIS 5.1 and 3) was explained with a combination of short duration and subsequent erosion or cover. In contrast, this detailed reconstruction shows four terraces underlying the raised MIS 5.5 shoreline, which in the Sibari Plain and Sila are reduced to three due to the large continental aggradation over the youngest, probably Holocene terrace. The four terraces (T0–T3) conceivably signal as many highstands younger than 124 ka (Table 3). In agreement with Cucci (2004), terrace T3 is attributed to the MIS 5.3 at w100 ka. The subaerial exposure of this terrace is supported by the w98 ka age of sample 1b (Table 2).

The lower terrace T2 is reasonably attributed to the MIS 5.1 at w80 ka. With an average uplift rate of 1 mm/a and a sea-level roughly 20 m lower than the present, the MIS 5.3 and 5.1 terraces are predicted to lie at w80 and w60 m elevation, respectively, coincident with the broad elevation where terraces T3 and T2 are mapped (Table 3). Terrace T2 has a sediment thickness (w10 m) comparable to T3, albeit the width is w3 times lesser (Table 1). Although the MIS 5.3 and 5.1 interstadials had a similar w20 m sealevel depth relative to the present, which could account for the comparable sediment thickness, the difference in width between T2 and T3 is not readily understood. This observation, however, might be reconciled with a larger duration of the MIS 5.3, as reflected by the longer highstand plateau sustained during the 5.3 than during the 5.1 interstadial shown in most sea-level curves (Waelbroeck et al., 2002; Lea et al., 2002; Siddall et al., 2003; Thompson and Goldstein, 2005). The following terrace, T1, is attributed to MIS 3 (Table 3). As for the upper terraces, this attribution is indirectly supported by the w44 ka age of sample 4 (Table 2), which, although resedimented in the Holocene terrace, would place a MIS 3.1 age constraint (Shackleton, 2000; Waelbroeck et al., 2002) on the terrace just above. Probably, T1 is polycyclic and was used during several relative highs of MIS 3. A cumulative MIS 3 age (up to w60 ka) is considered for T1, which was flooded by the sea at least up to w40 ka. With an average uplift rate of 1 mm/a and a sea-level at about 50 m lower than the present, a MIS 3 terrace should now stand at w10 m, the elevation of T1 (Table 1). Finally, terrace T0 might have a mid-Holocene age (Cucci and Cinti, 1998) or be just one of the MIS 3 highstands. The age attribution of terraces older than T4 is a more difficult task, due to the lack of datable material in situ. Samples resedimented in younger terraces, however, indirectly point to the existence within the flight of the pre-Late Pleistocene MIS 6, 7, and possibly 8 and 9 (Table 2). In order to avoid an unrealistically high

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Fig. 8. Depositional architecture and sedimentary facies of terrace T4, schematic map location and section location in Figs. 3a and 7, respectively: (a) Interpreted depositional sequence on the left bank of the Avena stream. The sequence displays a w10 m throw along the Avena–Lauropoli fault; (b) basal part of the T4 sequence lying with an unconformably sequence boundary (SB) on the Sub-Apennine clays; (c) cross-lamination in beach sand; (d) parallel lamination in beach sand; (e) regressive progradation surface (PS) between beach sand below and fluvial conglomerate above.

uplift rate cold stage terraces suggested by dated samples are considered as having been reshaped during the following warm stage. Concerning warm stages, two hypothesis invoking different uplift rates may be advocated. In a first hypothesis, terrace T5 is assigned to sub-stage 7.1 (Scheme 2 in Table 3). At several locations along this coast T5 has a substantial width (Table 1), which might suggest a polycyclic origin. Thus, in a different scheme, T5 might inglobate both interstadials 7.1 and 7.3, which were only separated by a short sea-level fall, with a larger plateau centered on MIS 7.3 at 215 ka (Waelbroeck et al., 2002). Likewise, terrace T6 might record the MIS 7. 3 or 7.5 (Table 3). Terraces from T7 upwards have a higher (w3 ) slope than younger terraces (w2 ). This is consistent with an attribution of T7 and superjacent terraces to older highstands, which accrued larger deformation. Terraces T7 and T8 might record interstadials 1 and 3 of MIS 9, or, in a different hypothesis, be

assigned to stages 7.5 and 9.1, respectively (Table 3). Similar considerations apply to higher terraces T9–T11 which might reflect MIS 11–15 or 9–11, respectively. 7.2. Relative sea-level changes In recent years, the refinement of eustatic curves has highlighted the existence of minor fluctuations of the sea-level even during second- and third-order Milankovitch cycles recorded in Interglacial sub-stages. These fluctuations have amplitude of up to w30 m and rates of up to w10 mm/a (e.g. Esat et al., 1999; Schellmann and Radtke, 2003; Potter et al., 2004; Radtke et al., 2004; Thompson and Goldstein, 2005), and thus largely exceed any tectonic signal. Through appraisal of several U–Th ages on corals worldwide, Thompson and Goldstein (2005) have proposed three

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Fig. 9. Heads of the coral Cladocora caespitosa found in deposits of terraces T7 (a) and T4 (b and c), location in Fig. 3d–e, respectively.

and two different sub-stages peaks within MIS 5.3 (at 100, 103, and 105.5 Ka) and 5.5 (at 115–116 and 118–125 Ka), respectively. The MIS 5.5 depositional sequence at the Pollino coast appears to be formed by two regressive cycles, separated by an episode of temporary emersion underlined by a coastal alluvial deposit (Fig. 7). Within the lower cycle, large-scale interfingering between the different beach sub-environments, although readily related to changing sedimentary dynamics, might in part reflect meter-scale changes in sea-level (Figs. 7 and 8a). The depositional sequence above terrace T4 records secondary eustatic changes during the Last Interglacial highstand. It might be argued that the variability in the sedimentary architecture may arise from changes in tectonic displacement rates during building of the terrace. It is clear, however, that tectonic rates of up to w1 mm/a controlled by

lithospheric or crustal scale dynamics in even a rapidly deforming setting such as the Calabrian arc (e.g. Westaway, 1993; Ferranti et al., 2006, 2007; Westaway and Bridgland, 2007) cannot keep pace with the superfast rates of sea-level change during the limited time-span of interstadial highstands (e.g. Lea et al., 2002; Schellmann and Radtke, 2003; Potter et al., 2004; Radtke et al., 2004). A eustatic signal is likely embedded in the Last Interglacial marine sequence of northeast Calabria. East of the study area, Carobene (2003) documented multiple cycles within the depositional sequence overlaying his terraces II and III, which in this scheme would represent the MIS 7 and 5.5 highstands. The hypothesis is supported by studies in stable coastal settings of Italy, like Sardinia where the MIS 5.5 highstand is found at the predicted eustatic elevation (Ferranti et al., 2006). At the eastern

Fig. 10. Geometry of terrace T2 depositional sequence at the Pollino coast. The sequence was reconstructed on the base of different observation sites (located by circled numbers in Fig. 3a). Eyes show idealized position of photographs in Fig. 6.

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Fig. 11. Representative sedimentary facies of T2, schematic location within depositional sequence in Fig. 10: (a) parallel lamination in fine grained beach sand; (b) coarse grained beach conglomerate foresets in sandy matrix; (c) medium grained coastal fanglomerate alternated to coarse sand.

Sardinia coastline, Kindler et al. (1997) documented the widespread existence of two regressive cycles separated by a local unconformity within the Last Interglacial sequence. Minor eustatic fluctuations might also be recorded by the depositional sequence overlying terrace T5, which displays diffuse alluvial intercalations within the marine aggradational body (Fig. 5). This further hypothesis is consistent with minor fluctuations during the MIS 7 in the sea-level curve of Thompson and Goldstein (2005). 7.3. Local tectonic control on the deformation profile of Pleistocene terraces The accurate mapping of terrace inner margins and depositional sequences coupled to the precise correction for stipulation of the

present paleo-shorelines position supply the critical ingredients for reconstructing the 2-D deformation pattern as recorded in coastparallel profiles of the Pleistocene terraces. Based on the high number of control points on past shoreline position and the admissible error on elevation estimate, a well constrained reconstruction of their present shape can be afforded which yields insight into the local contribution to total deformation (Fig. 12). As shown in Fig. 12, high densities of observation points (indicated by short thick lines with error bars) are available in the northern and southern parts of the region, and provide a tight constrain on the deformed shape of the coastline (dashed line fitting through datapoints). Conversely, larger uncertainty exists in the central sector mainly on the shape of the highest and lowermost terraces. This uncertainty is related on one hand to the more pronounced destruction suffered by the high terraces (T9–T11) in the more

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Table 2 New and existing radiometric data for marine terraces in north-eastern Calabria. No Fieldcode

Lab numbr

Elevation (m.a.s.l.)

1a J2A

K-5313

23

1b J2A 2 97

K-5313a K-53553B

23 53

3a 128

K-5355

Shell

Coordinates

3b 128

K-53553b 125

Cardium sp. N39 55’13.0’’ E16 35’08.7’’ Cardium sp. // Cardium sp. N39 46’24.06’’ E16 23’19.21’’ Cardium sp. N39 36’39.66’’ E16 26’44.65’’ Cardium sp. //

4

J14

Poz21913

Cardium sp. N39 54’33.2’’ E16 34’47.9’’

5

–

–

6

– a b c

–

125

2.5

114 65

Glycymeris sp. Glycymeris sp.

N39 52’39.92’’ E16 31’54.56’’ N39 52’17.33’’ E16 31’53.32’’

Locality

Age (ka  ka)

Torrace provenance

Field position Attribution

Tarianni

162  12a

T2

Resedimented

Tarianni Lauropoli

98  10a 262  46a

T2 T4

Vaccarizzo Albanese Vaccarizzo Albanese Avena

135  20a

T4

Resedimented MIS 5 (5.3) Resedimented MIS 7-8-9 (7.3/7.5/8/9.1) In place MIS 5 (5.5)

a

T4

Resedimented

MIS 7 (7.1–7.3)

T1

Resedimented

MIS 3 (3.1)

T4

In place

MIS 5 (5.5)

T3

Resedimented

MIS 5 (5.5)

Trebisacce Trebisacce

202  16

40  0.4 (Cal 44  0.39)b 130c 139

c

MIS 6 (6.5)

Electron Spin Resonance age performed at the Geographisches Institut, Universitat zu Ko¨ln, Germany. Radiocarbon age performed at Poznan Radiocarbo Lab, Poland. Calibration used the Fairbanks 0805 Calibration curve (Fairbanks et al., 2005). Predicted age from amino acid racemization value from Cucci (2004).

uplifted central sector, and on the other hand, to the substantial shedding of the lowermost terraces (T1–T3) beneath the aggrading and prograding Holocene plain. Notwithstanding, well constrained profiles for the intermediate terraces (T4–T8) can be propagated upward and downward to generate geologically feasible deformation profiles for the remaining terraces. Fig. 12 clearly illustrates that uplift of this region since the Middle Pleistocene had different amplitudes in spatially adjacent domains. Terraces on the Pollino coastal slope were uplifted faster than their counterparts on the Sila hillslope. The transition between the two sectors of different uplift is located between the Coscile and Crati streams, where a relative uplift low between the two mountain ranges is recorded by deformed terraces. In the Pollino sector, two individual culminations are recorded by paleo-shoreline elevations between the Coscile–Satanasso and Saraceno–Avena interfluves (Fig. 12). The Coscile–Satanasso coastal stretch appears to be the area of maximum uplift. The transition toward the Crati– Coscile low to the south is abrupt and is marked by a sharp kink in the deformation profile of the whole terrace flight. This pattern is consistent with a model of south-verging growth of a large-wavelength fold structure exposed on the southern border of the Pollino mountain range and imaged in its offshore extension by seismic profiling in the Amendolara submarine ridge (Fig. 1; Ferranti et al., in press). Beside this first-order signal, minor undulations with w1–2 km wavelength are apparent in the paleo-shoreline deformed profiles, which are attributed to parasitic or out-of-limb fault propagation folds, possibly accommodated on the left-transpressional faults mapped in the region (Fig. 1; Catalano et al., 1993; Monaco et al., 1998). The spatially distributed deformation accounts for the differential preservation of the terrace record, as recorded by the different width of the terraces across the Avena stream which separates two compartments of different uplift north and south of its course (Fig. 3a). The decreasing amplitude of the deformation profiles with younger terrace age indicates that differential uplift accompanied the regional vertical displacement of the coast during construction of the terraces. The syn-depositional nature of the deformation may be also recorded in the progressively higher slope values with terrace age (Table 1). The fact that differential deformation can be discerned even in the youngest (T1) terrace profile is consistent with seismological and geomorphic evidence of active deformation (Ferranti et al., in press). A local contribution to deformation is also supplied by extensional faults striking parallel to the Pollino coastline and part of the

Avena–Lauropoli fault system (Fig. 1). Large stretches of terraces have been down-dropped along this fault, which accounts for a local subsidence counteracting the differential uplift recorded by terraces (Fig. 12). The fact that this local subsidence is located in the sector of largest uplift like within the Raganello–Coscile interfluve supports the inference that the Avena–Lauropoli fault accommodates a deep-seated gravitational collapse triggered by localized uplift (Ferranti et al., in press). 7.4. Uplift rate history Besides the spatial variability documented by the shape of the deformed paleo-shoreline profiles, mapping and chronological analysis points to marked temporal changes in uplift rates, which were recorded simultaneously along the whole coastline of northeast Calabria. In order to elucidate the pattern of rate changes and appreciate its consistency regardless of the spatial differences in cumulative uplift, three individual transects located at coastal stretches which encompass the whole region under study and experienced local differences in uplift history were considered. The central transect is representative of the prominent structural high located on the southern border of the Pollino Range and is fitted to evaluate the area of maximum cumulative uplift (Fig. 12). The northern transect is located just south of the Avena stream and reflects the evolution of the northern structural high of Pollino, which accrued an intermediate magnitude of uplift. Finally, the southern transect is located at the Sila hillslope and provides an estimation of the minimum vertical deformation recorded at this coast. Reconstruction of the displacement history was performed by progressively computing the uplift accrued by each terrace order in the three transects (Table 3). For each of the eleven Pleistocene terraces, the measured inner margin was sequentially corrected to retrieve the nominal paleo-shoreline elevation as outlined in Chapter 4.2. This site-based correction takes into account the shedding of younger continental debris, the erosion recorded by the depositional sequence which attenuates the maximum sealevel elevation constrained by the top of foreshore deposits (e.g. Figs. 5, 7 and 10), and uncertainties in field measurements and in appropriate paleo-bathymetric correction (Table 3). Using the available chronological constraints, it is possible to place bounds on the total uplift experienced by individual terraces by adding or subtracting the eustatic difference between the present and the inferred paleo-sea-level, drawn from Waelbroeck

98 Table 3 Computation of time-partitioned uplift rates for terraces T1–T11at the southern, central and northern transects (location in Fig. 12). Note the age attribution according to two different schemes for terraces T6–T11. Corrections for nominal paleo-sea-level elevation as explained in text. The time-partitioned uplift rate is computed for the age interval between each chronologically ordered terrace pair (last column). Restored paleosea Measurement Bathymetric level elevation (m) error (m) uncertainly (m)

T1S T1C T1 N T2S T2C T2 N TT3S T3C T3 N T4S T4C T4 N T5S T5C T5 N T6S T6C T6 N T7S T7C T7 N T8S T8C T8 N T9S T9C T9 N T10S T10C T10 N T11S T11C T11 N

17 20 18 55 66 50 72 100 79.5 120 140 126.5 138 170 146 160 220 210 225 290 257 279 340 322 349 405 370 390 449 425 440 490 466

MIS

Age MIS (ka)a

Scheme 1 1 24 22 50 64 48 75 104.5 84 117 131.5 118 130 167.5 143.5 158 221 211 229 292 259 282 337 319 347 404 369 390 448 424 440 486 462

0 4 4 0 3 3 4 9 9 1 5 5 3 4.5 4.5 2 1 1 4 7 7 3 2 2 3 4 4 5 4 4 5 6 6

0 0 0 5 5 5 1 4.5 4.5 4 13.5 13.5 11 7 7 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 10 10 2 10 10 10 10 10 10 10 10 10 20 20

Age Eustatic (ka)a correction (m)a

Scheme 2

Uplift Time (m) partitioned uplift rate (mm/a)

Eustatic correction (m)

65/79 68/82 66/80 73.7 84.7 68.7 92.9 120.9 100.4 113.7 133.7 120.2 141.5 173.5 149.5 169.4 229.4 219.4 241.4 306.4 273.4 296.1 357.1 339.1 342.5 398.5 363.5 410 469 445 465 505 491

þ48/62

Scheme 1

3.3/3.1 61/40

3.3/3.1 61/40 þ448/þ62

5.1

82

5.1

82

19

5.3

101

5.3

101

21

5.5

124

5.5

124

6

7.3

215

7.1

197

4

7.5

236

7.3

215

9

9.1

287

7.5

236

16

9.3

313

9.1

287

17

11

407

9.3

313

6

13

533

9.5

331

20

15

621 11

407

25

Uplift Time (m) partitioned uplift rate (mm/a)

Markers coupletsb

65/79 68/82 66/80 73/67 84.67 68/67 93 120.86 100.36 114 133.70 120.20 148 179.68 155.68 164 223.54 213.54 234 299.38 266.38 295 356.37 338.37 366 422.11 387.11 385 444.32 420.32 434 473.57 459.57

T1/sea level

Scheme 2 1107/1.97 1.12/2.05 1.09/2 0.41/0.13 0.79/0.06 0.12/0.27 0.98 1.86 1.63 0.91 0.56 0.87 0.31 0.44 0.32 1.33 2.66 3.33 1.41 1.51 1.06 1.99 1.85 2.39 0.50 0.45 0.26 0.54 0.56 0.65 0.63 0.41 0.52

19

21

6

10

4

9

16

17

4

6

S ¼ Southern. C ¼ Central. N ¼ Northern. a Age and eustatic correction for T1–T9 after Waelbroeck et al. (2002): age and eustatic correction or T10 to T11 after Lisiecki and Raymo (2005) and lmbrie et al. (1984), respectively. b Sequential markers couplets for calculation of the time partitioned uplift rates.

1.07/1.97 1.12/2.05 1.09/2 0.41/0.13 0.79/0.06 0.12/0.27 0.98 1.86 1.63 0.91 0.56 0.87 0.46 0.63 0.49 0.88 2.44 3.21 3.37 3.61 2.62 1.20 1.12 1.14 2.62 2.43 1.81 1.16 1.35 2.01 0.63 0.38 0.51

T2/T1

T3/T2

T4/T3

T5/T4

T6/T5

T7/T6

T8/T7

T9/T8

T10/T9

T11/T10

E. Santoro et al. / Quaternary International 206 (2009) 78–101

Continental Terraceb Morphologic inner Erosion margin elevation (m) cover correction correction (m) (m)

E. Santoro et al. / Quaternary International 206 (2009) 78–101

99

Fig. 12. Coast-parallel profiles of the inner edge elevation of Middle–Late Pleistocene marine terraces in northeastern Calabria. Note that the profile runs NE–SW and NW–SE to the north and the south of the Coscile stream, respectively. Vertical boxes show the elevation transects used to compile the uplift rate history in Fig. 13.

et al. (2002) for terraces T1–T9, and from Imbrie et al. (1984) for terraces T10–T11 (age of these highest terraces drawn from the LR04 stack, Lisiecki and Raymo, 2005). Shown in Table 3 are two schemes that differ in specific MIS attribution of the Middle Pleistocene terraces, which lack adequate chronological constraints (see Section 7.1). The time-partitioned uplift rates were computed as the vertical displacement rate operating between the formation of two sequential terraces for each of the schemes (last column in Table 3). Significant differences between the two schemes are only recorded for some of the highest terraces (T7, T9 and T11). As the analysis chiefly deals with the more recent uplift pattern, which shows little differences in the two schemes for the last w250 ka, only results of this analysis using time and eustatic correction of Scheme 2 for the southern, central and northern transect are shown (Fig. 13). The time-integrated uplift rate history for the three transects during the last w400 ka provide two critical observations concerning the pattern of deformation accumulation. Primarily, uplift was not constant during time, but occurred as an alternation of more rapid (up to w3.5 mm/a) and slower (down to w0.5 mm/a) periods of displacement (Fig. 13). Large displacements were sustained for intervals lasting only few ten thousand years, as occurred

Fig. 13. Uplift rate history from w400 ka to the Holocene for three different transects along the coast of northeastern Calabria (location in Fig. 12). Incremental uplift values between pairs of terraces are listed in Table 3. The dashed line from w60 ka to the present illustrates the possibility that terrace T1 represents only the shallowest MIS 3.3 interstadial. Alternatively, terrace T1 probably embeds the whole duration of MIS 3 from w60 to w40 ka, as listed in Table 3.

during MIS 9, 7 and the second half of MIS 5. This coast probably entered a period of rapid uplift since w50 ka, which continues today. In contrast, slower displacements have a larger duration of between w40 and 60 ka. It is possible, however, that the duration of these intervals be different because the information from cold stages into the rates history cannot be incorporated. Nonetheless, the temporally non-uniform evolution of uplift rates is evident. This finding is consistent with the well established pattern of clustered activity along crustal faults (e.g. Friedrich et al., 2003; Ferranti et al., 2007; Oldow and Singleton, 2008). This analysis differs from previous interpretations (Cucci and Cinti, 1998; Bordoni and Valensise, 1998; Cucci, 2004) that argued for constancy in uplift rates at 1 mm/a since the Middle Pleistocene. Although these workers regarded the MIS 5.5 marker – the starting assumption of their analysis – to have experienced the same uplift as found in the present work, the finding of more terraces beneath the Last Interglacial marker documented by this analysis suggests that a more complex temporal behavior is feasible, and might be exported to pre-Late Pleistocene terraces as well. Similar perplexities in averaging the Last Interglacial tectonic rates over different time intervals were previously raised at different locales of the Calabrian arc (Miyauchi et al., 1994; Antonioli et al., 2006). The second important issue highlighted by this analysis concerns the spatial variability in uplift rates discussed in the previous section, but with the addition of a clear understanding on how this variability was partitioned through time. A closer inspection at Fig. 13 reveals that the different magnitude of cumulative uplift in the three sectors was accrued neither abruptly nor progressively, but during discrete episodes of differential displacement. It appears that a differential displacement of w40 m between southern Pollino and Sila (central and southern transects, respectively) occurred around w220–200 ka. A second increment of w30 m differential displacement between the two sectors was accrued shortly after w100 ka (Fig. 13). The fact that the three coastal transects experienced simultaneous periods of rapid and weak uplifts suggests that the sources of these variations had a broad, regional extension, and must be probably searched within the deep processes controlling the dynamics of the Calabrian arc (Westaway, 1993; Wortel and Spakman, 2000; Gvirtzman and Nur, 2001; Ferranti et al., 2006; Westaway and Bridgland, 2007; Ferranti et al., 2007). However, it is also apparent

100

E. Santoro et al. / Quaternary International 206 (2009) 78–101

that occurrence of local displacement was temporally tuned with intervals of rapid regional uplift (Fig. 13). This fact strongly points to the coupled behavior between shallow and deep deformation processes in the Calabrian arc (Ferranti et al., 2007, in press). 8. Conclusions Raised Middle to Late Pleistocene marine terraces on the eastern side of northern Calabria were used to investigate how vertical displacements occurred in a non-steady state fashion both in space and time. Although significant uncertainties still surround an accurate age assignment of the whole terrace flight, detailed mapping and correlation of terrace inner margins, and precise correction for paleo-shoreline elevation position indicates that uplift occurred as a sequence of more rapid and slower displacement episodes along the whole coastal transect. Rapid displacements at over w3.5 mm/a were sustained for few ten thousand years, and, in contrast, slower displacements at rates of w0.5 mm/a might have had a larger duration of around w50 ka. Whether this reflects a change in regional uplift processes, controlled by lithospheric slab dynamics or lower-crustal flows, or variation in the activity of upper crustal structures represented by transpressional folds, is not resolved. Local structures, however, exerted a strong control during regional uplift, since they modulated the differential growth of closely spaced highs and lows as recorded in the deformation profile of terraces parallel to the coast. At a larger scale, the coastal Pollino Range in the northern side of the Sibari Plain was uplifted faster than the hillslope of Sila Massif on the southern side of the plain during the Late Middle Pleistocene. During the second half of Late Pleistocene, the coastal sectors of both ranges were uplifted at a broadly comparable rate. The differential deformation during construction of the coastal flight is reflected in the spatial degree of development and preservation of terraces and overlying depositional sequences. Notwithstanding, depositional sequences were fully developed also in the sectors of higher uplift rates, like at the Pollino coast, indicating that creation of accommodation space during fast sea-level rise coupled to huge sedimentary supply from the rising land overwhelmed the tectonic uplift rate during Interglacial highstands. Based on this, the recognition of two regressive marine cycles separated by a continental layer in the depositional sequence of MIS 5.5 and 7 supports global inferences of minor sub-orbital sea-level changes during interstadial highstands. Acknowledgments This work was supported by PRIN 2005 and INGV-DPC 2007– 2009 grants to L. Ferranti. Work in the Sibari Plain was funded by Doctorate Programs on Scienze della Terra (M.E. Mazzella) and Scienza e Ingegneria del Mare (A. Randisi) at the University of Naples, and Geodinamica and Sismotettonica at the University of Catania (E. Santoro). We thank V. Di Donato and P. Esposito for foram and nannofossil analysis, and P. Cappelletti for calcitearagonite determination on Cladocora samples. We are also grateful to Norm Catto for his Editorial guidance and to two anonymous reviewers for their comments. References Antonioli, F., Ferranti, L., Lambeck, K., Kershaw, S., Verrubbi, V., Dai Pra, G., 2006. Late Pleistocene to Holocene record of changing uplift rates in southern Calabria and northeastern Sicily (southern Italy, central Mediterranean Sea). Tectonophysics 422, 23–40. Amato, A., 2000. Estimating Pleistocene tectonic uplift rates in the South-Eastern Apennines (Italy) from erosional landsurfaces and marine terraces. In: Slaymaker, O. (Ed.), Geomorphology, Human Activity and Global Environmental Change. John Wiley and Sons, London, pp. 67–87.

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