Geology versus myth: the Holocene evolution of the Sybaris Plain

L. Cucci

Abstract


Historical accounts handed down the legend of the ancient Sybaris, defeated and submerged by the Crotoniates who
diverted the River Crati on the town. This paper deals with the reconstruction of the Holocene evolution of the
Sybaris Plain, through a number of geological and geomorphological observations. In particular, I found i) ?1 m/yr
horizontal coastal progradation rate since Greek times (2.4 kyr BP), possibly since Neolithic (7.0 kyr BP), mainly
originated by active alluvial deposition and subordinately by regional uplift; ii) evidence of striking modifications
in the surface hydrography of the plain during the last 2.5 kyr, with repeated fluvial captures of the Crati and
Coscile rivers testified by ancient historians and geographers, recent maps and archeological accounts. In addition,
datings and archeological information from 7 sites in the plain provided iii) ?0.6 mm/yr mean uplift rate during the
past 11.2 kyr, that confirms the substantial continuity of this regional process with upper Pleistocene; iv) local, high
value of subsidence (0.5÷2.0 mm/yr) affecting the Sybaris main archeological area. Subsidence is not recorded before
4000 years BP and is caused by deposition of fine, highly compressible sediments at the transition between
marine and continental environment; v) no evidence of a fault-induced contribution to the subsidence, whilst there
is the grounded possibility that man-induced subsidence prevailed in the last century; vi) widespread active continental
deposition in the area. Local rates of deposition are relatively lower (1.5 mm/yr) at sites where subsidence
is not observed, and range between 2.5 mm/yr and 3.5 mm/yr in the main archeological area. There is also evidence
of a clear decrease of the sedimentation following the Mid-Holocene flex of the fast trend of sea level rise. These
data suggest that the Holocene evolution of the Sybaris Plain is due to the progressive eastward migration of the
land-sea boundary, probably active since the Mid-Holocene (?7.0 ka). Repeated floodings, regional uplift and relative
sea-level changes produced the eastward expansion of the plain, subsidence locally slowed it down. Therefore,
geology first allowed the creation of Sybaris, then caused its destruction.

Keywords


Holocene;Sybaris;coastal progradation;uplift;subsidence

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References


DOI: https://doi.org/10.4401/ag-3251
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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X