1Sybaris was, for a time, the largest and most powerful Archaic Greek settlement of Magna Graecia in southern peninsular Italy. Early archaeological exploration to discover its location in the NE sector of Calabria began during the last quarter of the 19th century. Searches concentrated along the northwestern Gulf of Taranto, at the base of Calabrian highlands (Pollino Chain to north, and Sila Massif to south) and on the contiguous Sybaris plain of the Crati Delta (fig1).
Fig.1 - Maps showing the Casa Bianca study area on Sybaris plain of the Crati Delta, ~2.5 km west of the modern Crati River mouth.
Settlements of Sybaris, Thuri, and Copia are superimposed (upper left inset, modified after Cerchiai et al. 2004). Lower map reveals Casa Bianca excavation, core sites CB1 and CB2, and other features; numbers in and surrounding excavation indicate elevations relative to msl (data after Sybaris Museum survey).
2However, the delta plain surface revealed only limited amounts of ancient archaeological material and no obvious relief manifestations indicating presence of early underlying settlement structures. What proved most daunting was the more than 4 m of Crati Delta alluvial sediment that had buried the late Holocene coastal sedimentary sequences on which Sybaris had been constructed. It became readily apparent that more than standard archaeological approaches were needed to explore such a large area.Sybaris’ exact location and regional configuration in subsurface would remain poorly defined until well into the 20th century. Sybaris (Archaic Greek) and two younger sites partially superimposed above it, Thuri (Classical Greek) and Copia (Roman), owe their discovery largely to intense geoarchaeological exploration efforts. Mapping of Sybaris’ locality and that of the two overlying sites beneath the thick sequence of deltaic deposits on the lower Sybaris plain was achieved only after a massive exploratory core drilling project in the early to mid-1960s. This entailed recovery of more than 1529 sediment borings throughout an area exceeding 140 km2, with drill cores that ranged from 1 to 27 m (most 6 to 9 m) in length (Rainey and Lerici,1967). The drilling program was complemented locally by subsurface geophysical surveys. Defining the location of Sybaris and two overlying sites buried beneath the thick cover of deltaic sediment was made primarily by defining the distribution of archaeological material in borings, mostly sherds and small construction fragments (Rainey and Lerici,1967).
3The three buried sites trend toward east-southeast and southeast, with successive population centers positioned about 2.5 km west of the present Gulf of Taranto coast and landward of the two-winged, cuspate-shaped delta margin (figs.1, 2A).
Fig.2 - Photographs of study area.
A, satellite image (May 17, 2006; Google Earth 2008 Tele Atlas) shows Crati River channel (Ch), sand beach ridges (Br) northwest and south of Crati mouth, sandbar (Ba) off mouth, wetlands (We) west of mouth, and Laghi di Sibari marina and residence construction in former wetland area.
B, view of Sybaris plain from south of Crati River.
C, sandbar (Ba) seaward of Crati mouth (June 2007); note beach formed of coarse sand and pebbles, with abundant plant matter.
D, wetland landward of the Crati coastal beach ridge, including brackish to fresh water marsh and swamp environments.
E, Casa Bianca excavation viewed toward west from core site CB2. Beneath excavated delta alluvial sequence (DAS) are Thuri port facilities that, in foreground, include a ship slip (SSl).
F, dark organic-rich sediment (Os) mixed with archaeological material in Copia horizon, at base of Casa Bianca excavation.
4After abandonment, they were buried for about 2100 years by thickening sequences of late Holocene deposits of the Crati and Sybaris (now called Coscile) rivers. Once identification of artifacts in cores was complete, the task of excavating settlements and defining the pre-burial geography of the area in Greek and Roman time awaited archaeologists. This involved arduous and costly processes to overcome effects of flooding in each excavated depression due to the shallow ground water level lying at only ~2 m beneath the present plain surface of the lower Crati Delta. The problem was compounded in that tops of ancient human structures are positioned below ground water level, at elevations of 1.5 m or more beneath present mean sea level (msl). Excavation of subsurface horizons to expose human levels in archaeological pits became feasible only after emplacement of an extensive well-point system and continuous pumping of water away from each of the large, deeply excavated areas (Cotecchia and Pagliarulo, 1996).
5The drilling program in the 1960’s indicated that, in general, light colored mud-rich alluvial sediment of Crati and Coscile rivers covers the three sites, while darker sandy and silty units form substrates beneath Sybaris and the two overlying settlements. A sand body beneath Sybaris was interpreted as dune and/or beach material formed as a north-south oriented coastal ridge (Rainey and Lerici, 1967). Its orientation is similar to those of younger linear N-S surface relief features on the lower Sybaris plain near the present Crati Delta coast (Guerrichio and Ronconi, 1997, Bellotti et al, 2003-4). The presence of occupied sites in close proximity to coastal wetland settings was also recognized by Rainey and Lerici (1967), and subsequently by Guerrichio and Ronconi (1997), Hofman (2002) and Bellotti et al.(2003).
6The Crati Delta is an active eastward-migrating depositional system whose evolution directly impacted Greek and Roman populations during the time of settlement along the coast (Bellotti et al., 2007). Our study focuses on progressive change of natural events that affected the three settlements from the 8th to 1st centuries BC as the delta prograded seaward. For the investigation, two continuous sediment cores were collected in the Casa Bianca area at the easternmost sector of the Sibari archaeological park (fig.1). Herein, focus is on temporal and geographical attributes of environmental settings in this sector so as to more precisely identify changes in time and space that affected the three sites before, during and following the delta’s eastward seaward progradation into the northwestern Gulf of Taranto. It is useful to evaluate how Sybaris, Thuri and Copia, each at one time positioned in the immediate vicinity of the Gulf of Taranto coast, eventually became separated from the migrating shoreline.
7Sybaris (720-510 BC) was a city renowned for its fertile soil, rich trade and agricultural bounty. Founded by settlers from Achaea in the northern Peloponnesus, it was a coastal agricultural and trading center that reached its height during the 6th century BC (Cerchiai et al, 2004). Early writers provided few details about Sybaris, and even Herodotus (c. 484‑425 BC), in The History, does little more than vaguely allude to its geographic position in an area between courses of the Crati and Sybaris (known today as Coscile) rivers (fig.1, inset). The wealth and excesses of this center over time are believed to have lead to its downfall and ruin. Following a period of serious internal civil political discord, the city was overthrown in 510 BC by Crotone, a powerful colony positioned to the south on the Ionian coast.
8After a period of abandonment, Sybaris was reconstructed in 444-443 BC by Athenians and renamed Thuri, before being subject once again to wars and periodic destruction (390-285 BC). Following this, a center known as Copia was reestablished (~282 BC) and then occupied in 194 BC by Romans. The town declined from the 1st century BC to the 3rd century AD, and final abandonment of this sector on the deltaic plain occurred in the 9th century AD. An excellent review of early quotations pertaining to Sybaris and Thuri, dating from Scylax (521-485 BC) to Photius (about the 9th century AD), is presented by Rainey and Lerici (1967, p.1-36). Although question remained as to Sybaris’ location at Parco del Cavallo (fig.1) after the 1960’s exploration results were published (Tricoci, 1972), most subsequent archaeological studies now support this lower Crati Delta plain sector as the Sybaris site (Guzzo, 1973, 1981).
9Historians and archaeologists have generally interpreted the repeated construction-destruction-abandonment-reconstruction cycles of the ancient cities on the Sybaris plain in terms of human intervention, mostly political unrest and battles. While these events are not to be minimized, it has also become apparent, especially to geologists and geographers, that natural factors prevailing in this region during the late Holocene also played a significant role in the history and evolution of the three successive cities. Among critical factors that affect this geologically active sector are structural mobility and consequent land uplift and subsidence (Lanzafame and Tortorici, 1981; Colella, 1988; Cherubini et al., 1994, 2000; Cotecchia and Pagliarulo 1996; Carobeneet al., 1997; Cucci and Cinti 1998; Bentivenga et al., 2004; Ferranti et al., 2006). Concurrent sea-level rise (Lambeck et al., 2004) would also have impacted population sites once positioned on the mostly flat, low-lying (Istituto Geografico Militari, 1967), and thus vulnerable, lower delta surface once positioned at the coast (fig.2A, B). To these two factors should be added the importance of climate, and especially fluctuating seasonal and storm-associated rainfall (Frazzetta et al., 1977), that had a direct effect on sediment discharge on the delta plain and coastal development. The Crati Delta coastline records long-term seaward sediment accretion and build-out into the Gulf of Taranto, indicating that over time, deposition has had a stronger role than erosion by near-shore currents at the delta margin. Much Crati fluvial sediment reaches the river mouth, and what is not deposited there or displaced laterally by coastal currents by-passes the shore and reaches marine settings deeper in the Gulf of Taranto (Colella et al., 1981, 1984; Ricci Lucchi et al., 1983-4).
10Finally, information is available on petrologic attributes of sediment units on which the cities were built. For example, textural and mineralogical data (cf. Dell’Anna and Rizzo, 1982-3, Dell’Anna and Laviano 1988, Bellotti et al.,2003-4) provide a means to gauge sediment provenance and dispersal transport paths via the Crati and Sybaris rivers before, during, and after time of settlement of the three cities. Grain size parameters and physical and geotechnical properties of the sediment substrate have also been used to elucidate the role compaction has played in delta plain subsidence (Cherubini et al., 1994, 2000; Cotecchia et al., 1994; Pagliarulo et al., 1995).
11Integration of the above diverse natural factors provides a reasonable means to explain how the Crati Delta margin-marine boundary has migrated eastward of into the Gulf of Taranto. Additional interpretations of Holocene evolution of the Crati Delta, especially those that use the modern Crati Delta coastal margin as model (fig.2A), are discussed in syntheses by Bellotti et al., (2003-4) and Cucci (2005).
12Elevation of the current delta plain in the archaeological park ranges from ~2.5 to 4.0 m above msl. Three archaeological levels at the Parco del Cavallo excavation ~700 m west-southwest of the Casa Bianca study area (fig.1, inset) are, core-upward, at the following approximate elevations relative to msl (Pagliarulo, 2006): Sybaris, -3.5 m; Thuri, -1.26 m; and Copia, +0.5 m. The water table in that area lies at about +2.0 m. The present study concentrates on the easternmost part of the Sibari archaeological park, in the deeply buried (~ 4 m beneath the Sybaris plain), elongate (235 m long), pentagonal-shaped Casa Bianca excavation (fig.1). This sector is known to comprise Thuri and Copia, the two superimposed population centers that succeeded Sybaris. From previously existing core and exploratory data, it does not appear that the towns extended much to the east beyond this Casa Bianca sector. The surface elevation of the delta plain surrounding the depression is about +2.5 m. The eastern part of this excavation reveals remains of port facilities, including what has been attributed as a ship slip positioned within the walled eastern end of Thuri (figs.1, 2E; Zancani Montuoro, 1972-3; Blackman, 1977).
13The numerous published 1960’s core logs (Rainey and Lerici, 1967, p.136-250) are a valuable archaeological database, but are insufficiently detailed for thorough lithofacies analyses. Also available are generalized lithologic logs of more recently recovered long sediment cores (some to c. 100 m in length) that have served primarily for geotechnical purposes (Cherubini et al., 1994, Cotecchia et al., 1994, Pagliarulo et al., 1995; Guerricchio and Ronconi, 1997; Cucci, 2005; Pagliarulo, 2006). Some of these core sections have been radiocarbon dated and provide a valuable stratigraphic base for late Pleistocene to Holocene sediment sections in the Sybaris archaeological park, including the Casa Bianca study area. Dates show that the Pleistocene-Holocene boundary (roughly 10,000 years before present) in this sector lies at depths of ~ 50 m (Pagliarulo 2006). However, for this study that focuses on the late Holocene, particularly the upper 8 m or so of section that comprise Greco-Roman archaeological material, we required fresh continuous core sections for detailed decimeter-by-decimeter analyses.
14Two new drill cores, CB1 and CB2 (fig.1), were thus recovered at the Casa Bianca locality to detail the sedimentary petrology (figs. 3, 4), fauna and biofacies (data in Bernasconi and Stanley, study in preparation), and lithostratigraphy (fig. 5) of the substrate.
Fig.3 - Selected sediment sections from core CB1 within Casa Bianca excavation site (core log in fig.5).
A, rock fragments, brick material, and ceramics including a piece of tile (arrow) from Copia horizon (unit 1c, elevation -2.0 m); this was buried by now-excavated tan and mottled silt-rich delta plain sediment.
B, brick fragments (arrows) in sandy facies from Thuri horizon (unit 1b, ele. -3.0 m).
C, dark grey organic-rich sand and silt facies (unit 3, ele. -3.5 m) beneath Thuri horizon.
D, Sand with fragments of brick and small rock (arrows) from Sybaris level (unit 1a, ele. -4.5 m).
E, alternating coarse sand and silt facies (unit 4, ele. -6.0 m).
F, coastal ridge facies (unit 5, ele. -7.2 m) comprises coarse sand with small pebbles (long diameter of one shown by arrow = 1 cm). Bar scale on each image = 2 cm.
15These attributes serve to define Crati Delta migration in Greek and Roman times relative to the locality of ancient sites and help determine the sequence of environmental settings which enabled ships to approach and land at the cities. Continuous core sections were obtained using a CMV MK600 drill system. Sediment borings had a 10 cm diameter. The top of core CB1 was drilled in the Casa Bianca excavation proper, at the level of Copia. Here, the upper delta plain (DAS) sequence had been removed by excavation to an elevation of -1.6 m beneath msl (fig.5), and the base of the 20 m core section reached an elevation depth of -21.6 m beneath msl. Core CB2 was drilled 130 m east of core CB1 on the delta plain surface at an elevation of about +2.4 m; that 22 m-long core section reached an elevation depth of -19.6 m.
16Core CB1 (fig.5) recovered 3 archaeological horizons between core top at -1.6 and -4.6 m. These range in thickness, from top to bottom: unit 1c, ~0.9 m; 1b, ~0.2 m; and 1a, ~0.25 m. These sections included orange brick and light grey lithic-rich fragments embedded in dark grey to olive-grey, medium and fine sand and silt (units 2 and 3, total of ~2.5 m thick). Encountered deeper down-core beneath anthropogenic levels are the following facies: alternating coarse sand, sand and silt strata (fig.3E; unit 4, ~1.9 m thick); coarse sand with small pebbles (fig.3F; unit 5, ~1.6 m thick); alternating sand and silt laminae (unit 6, ~2.0 m thick); micaceous-rich sand and silt (unit 7, ~1.5 m thick); and organic-rich sediment (unit 8, > 1.5 m thick).
17Core CB2 (fig.5) collected just east of the excavation obtained the following sequence from its top to an elevation of -13.5 m beneath msl: silty mud of delta alluvial origin (DAS, ~4.4 m thick); a section of dark olive-grey organic-rich sand and silt (unit 8b in fig.4F, ~3.0 m thick) that includes two distinct layers of archaeological material, including orange brick and grey lithic fragments (upper unit, 1c in fig. 4B, is ~0.15 m thick; lower one, unit 1b in fig.4E, is ~0.2 m thick). The sequence of sediment facies beneath the lower archaeological horizon is similar to those at core CB1 to the west, but each facies lies at shallower depths (~1.0-1.5 m higher elevations) than equivalent ones in CB1: a horizon of alternating coarse sand, medium to fine sand, and silt (unit 4, ~0.8 m thick); coarse sand with small pebbles, some with a diameter to 2 cm (unit 5, ~1.40 m thick); an alternating sand and silt sequence with shallow marine fauna (unit 6, ~0.9 m thick); and a thick micaceous-rich sand unit in which a dark organic-rich sandy and muddy silt is inter-bedded (units 7 and 8, > 5.0 m thick).
18The three archaeological-rich levels in core CB1, from top to base (fig.5; units 1c, 1b, 1a), are attributed here to Copia, Thuri, and Sybaris, respectively (fig.3A, B, D). They occur at elevations from -1.5 to -4.7 m, and the three are spaced apart at vertical intervals similar to those recorded at Parco del Cavallo (Pagliarulo, 2006). The presence of human material (unit 1a) in CB1, attributed here to the Sybaris level that underlies the Thuri and Copia excavation farther to the west, was unexpected (Dr. Lupino, personal communication, 2008), and is a noteworthy finding (fig.5). Core CB2, on the other hand, only 130 m due east of CB1, recovered only two archaeological levels (units 1c, 1b), interpreted as Copia and Thuri (fig.4B, E).
19The above-listed five levels of human activity in the two cores are mostly interbedded with, and underlain by, sediment comprising dark (grey, olive-grey) organic-rich sandy and silty units, sometimes with mica and dark grey to black plant matter (figs. 3C, 4C, D, F). The occupation levels, and organic-rich deposits (fig.2F), were buried by an overlying sequence of approximately 4 m of distinct finer-grained, tan to light grey and mottled, delta alluvial plain deposits (fig.4A; DAS in figs. 2E, 5).
20Interpreting the late Holocene paleogeographic evolution of the Crati Delta section now buried beneath the lower Sybaris Plain surface is assisted by applying the Lyellian principle of the present as key to the past. In this respect, recent development of the Crati Delta coast provides a reasonable analog of past conditions, and suggests that the modern sea-to-land (east-to-west) sequences here are comparable in major respects to late Holocene subsurface sediment facies now buried at Casa Bianca. The modern Crati mouth is bound to the northwest and south by broad, low linear coastal ridges (fig.2A) formed of coarse sand and pebbly sand rich in plant matter (fig.2C) with, locally, heavy mineral concentrations. Sand ridges, especially those near the Crati mouth, are backed landward by wetlands (fig.2A), including small estuaries, marshes and swamps (fig.2D) and woodland remnants. Agricultural fields on the Sybaris plain extend to within 500 m of the present coastline (fig.2B).
21The two core logs in figure 5 show a similar superposition of facies, including a coarsening-upward of shallow marine sequences as defined by their biofacies (cf. Di Geronimo and Robba 1976, Bernasconi and Stanley, in preparation). Farther upward, these change to a variety of coastal sediment types (including coarse beach to dune ridge sand to organic-rich wetlands) and, finally, to delta alluvial sequences (DAS). It is of note that this older-to-younger upward temporal facies series in the two cores closely parallels the spatial landward-trending (east to west) facies sequence, from offshore shallow marine landward to Crati coast and delta plain (fig.5, upper right diagram). This latter pattern indicates (1) modern coarsening of facies from shallow marine inner shelf in the Gulf of Taranto to the beach (fig.2C), (2) then to facies extending landward as diverse sand-rich coastal beach and dune ridge (fig.2A) and, behind the ridge, as organic-rich wetland (marsh and swamp) facies (fig.2D), and (3) still farther inland to delta plain alluvial deposits (fig.2B).
22The absence of coarse sandy conglomerate and pebble-rich sand above the three buried human levels indicates that the two core sites during time of occupation in the late Holocene were positioned at some distance from direct channel flow of the Crati and/or Coscile (Sybaris) rivers that normally transport coarse sand and pebble-rich loads in their channels. This finding bears on the long-discussed account of the demise of Sybaris, related by Strabo (64 BC-21 AD). About five centuries after the event had supposedly occurred, this scholar wrote the following about the Sybarites in his Geography (VI, 1): “by reason of luxury and insolence they were deprived of all their felicity by the Crotoniates within seventy days; for on taking the city these conducted the river over it and submerged it.”
23Subsurface stratigraphic information available for the Casa Bianca sector derived from long cores collected by others (Pagliarulo, 2006), and now from cores CB1 and CB2 in this study (figs.3-5), does not record coarse pebbly sandy mud and conglomerate deposited directly above human occupation levels in borings. Based on data collected to date, it appears that burial of Sybaris about 2500 years ago, and subsequently that of the two overlying settlements in the Casa Bianca excavation, more likely occurred as a result of natural processes such as fluvial over-bank alluviation on the delta plain from the migrating Crati-Coscile fluvial systems. Recovery of additional closely-spaced cores and detailed facies analyses will eventually confirm, or lay to rest, Strabo’s account.
24Sediment facies in CB1 and CB2 record lower elevations along a landward track, from east to west (fig.5). For example, wetland deposits presently at depths of 0.0 to -1.0 m msl landward of the modern coastal ridge are at depths from -2.0 to -5.0 m below msl in core CB2 at Casa Bianca. The beach ridge unit formed of coarse sand with small pebbles typical of the present shoreline (facies 5 in fig.5) lies at -5.8 m in CB2 and -7.0 m in CB1. Somewhat higher elevations (by about 1 m) of Holocene facies in core CB2 than in core CB1 are attributed in part to progressively increased sediment compaction landward behind the easterly prograding delta coast. This factor has caused subsidence of the Crati Delta’s lower plain behind the coastal ridge and, consequently, locally increased deltaic accumulations (DAS), especially in topographic lows.
25Using approximate ages of 2250, 2350 and 2600 BC to date archaeological levels at core sites CB1 and CB2, and taking into account their present depths beneath msl at the two core sites (fig.5), the following average rates of subsidence are obtained: in CB1, 1c, Copia, 0.9 mm/yr; 1b, Thuri, 1.3 mm/yr, 1a, Sybaris, 1.7 mm/yr; and in CB2, 1c, Copia, 1.1 mm/yr, 1b, Thuri, 1.5 mm/yr. The overall average subsidence rate averaged for all 5 human horizons positioned about 2.5 km from the present coast is 1.3 mm/yr. Moreover, an average subsidence rate of 1.7 mm/yr is calculated for this park sector based on a published radiocarbon date of 3561 years before present for a sample at -6.0 m below msl in core S18 recovered by other workers (Pagliarulo, 2006).
26That rates increase somewhat with age and depth in both cores is attributed in part to underlying substrate sediment compaction that has led to delta plain subsidence. There are marked differences of subsurface strata elevations between CB1 and CB2 over a distance of only 130 m, or a time period representing roughly 130 years. This significant difference in vertical displacement records stratigraphic offset at depth, perhaps due to sediment failure and/or faulting between the two core sites in addition to compaction effects beneath the Thuri-Copia settlement. Subsidence rates calculated here, however, should be envisioned as relative subsidence values inasmuch as they indicate lowering on a delta plain that at times may have been subject to regional uplift (cf. Cucci, 2005).
27Sediment deposits in the two cores summarized earlier (fig.5) document the changing of Crati Delta coast positions that would have directly impacted eastern sectors of still-occupied Sybaris, Thuri, and Copia. Observations here generally confirm the contention of earlier studies, i.e. that Sybaris had originally been sited on, or near, a coastal ridge setting proximal to a wetland lagoon (Rainey and Lerici, 1967; Hofman, 2002; Guerricchio and Ronconi, 1997; Bellotti et al., 2003). Documented changing lithofacies distributions record the timing and extent of dynamic seaward (eastward) accretion of the delta coast where the three settlements were successively placed from the early 8th to the 1st century BC.
28The major center of Sybaris was located close to Parco del Cavallo, ~700 m west of Casa Bianca. Core CB1, however, unexpectedly recovered anthropogenic material ~1.5m beneath that of the Thuri level (fig.3D), as at Parco del Cavallo. Core analysis suggests that the coastal sand ridge setting of the type on which Sybaris had been built to the west (Liguori 2005) had likely migrated east of the CB1 site location by the 6th century BC (fig.6A). From the time of Thuri (fig.6B) to that of Copia (fig.6C), the area between core CB1 and CB2 became a wetland environment, one that appears to have included a dredged channel or canal setting. That feature is identified by a heterogeneous mix of anthropogenic material (mostly brick and lithic fragments) dispersed in unstratified, dark organic-rich silty and sandy muds (fig.4C, D). It is assumed to have been associated with the ship slip (Zancani Montuoro, 1972-3, Blackman, 1977) identified at the easternmost end of Thuri (figs.1, 2E). Such a channel would have facilitated passage of boats closer to the settlement via a wetland that was then positioned already landward of the coast proper (fig.6B). To better define the configuration of the lagoon and possible relation of the artificially modified waterway to the ship slip at Thuri would require collecting
a series of closely-spaced cores in this area.
29By the 1st century BC, or less than 700 years after founding of Sybaris, wetland settings landward of the coastal ridge had shifted considerably east of core site CB2 (fig. 6D). Moreover, remnants of the three settlements became increasingly separated from the Gulf of Taranto shoreline during the past ~2100 years. The 2.5 km distance between the Casa Bianca area and present Crati Delta coastline indicates an average annual rate of seaward coastal advance of ~1.0 m per year since time of Sybaris. Coastal advance rates periodically increased to as much as 2.0 m per year (Cucci, 2005). Shoreline accretion at times also stopped and reversed direction, with the coast retreating landward, when the Crati River channel shifted north and south of its present trace, and/or at times of increased shoreline erosion relative to flood discharge and coastal accretion (cf. Wright and Coleman, 1973). Examples of such short-term Crati River mouth position changes and coastline fluctuations in recent time are illustrated by Bellotti et al.(2003-4). Overall, however, a long-term average 1.0 m/year seaward accretion rate of the delta coast has prevailed as recorded by various observations. One, for example, calls attention to the present position of two observation towers built for warning and defense purposes and originally placed near to the shoreline during the first half of the 16th century (Cucci, 2005). These structures, now positioned ~ 400 m landward from the beach, record an eastward coastal progradational rate of 0.8-0.9 m/year.
30It is noted that evolution of ancient sites on the Crati Delta is significantly different from those of Greek settlements positioned on the southern Calabrian coast, such as at Kaulonia and Locri (Stanley, 2007; Tennent et al., 2009). There, the shoreline along the Ionian coast at times during the late Holocene also migrated seaward separating settlements modest distances from the sea, but not because of excess alluvial sedimentation at the coast by reason of delta margin progradation. Rather, distancing of settlements from their Ionian shore resulted from coastal uplift in highly active sectors of the Calabrian arc where rapid tectonically-induced shifts of land displaced the shoreline in a seaward direction.
31In summary, continued net seaward shoreline shift to the east of the Casa Bianca area was a function of important Crati River sediment accretion rates that successively land-locked Sybaris, Thuri and Copia away from the coast. This distancing from the shore, in turn, altered navigational patterns that were of direct importance to the economic well-being of the three settlements. The decreased access to proximal ship landing on beaches and at port facilities at the sites associated with the seaward migrating delta margin ultimately became the major factor responsible for altering their navigation, and thus their trade patterns, in this sector of the ancient world.
We thank Dr. S. Luppino, Director of the Sybaris Museum and Archaeological Park, for her kind support and that of the Soprintendenza per i Beni Archeologici della Calabria that made it possible for us to carry out research at the Casa Bianca archaeological excavation. We also acknowledge Ms. A. Kreuzer for her technical assistance with the figures and typescript preparation. Funding for fieldwork was provided by the National Museum of Natural History, Smithsonian Institution.