LA RISPOSTA AMBIENTALE ED UMANA ALLE OSCILLAZIONI CLIMATICHE SUB-ORBITALI DELL’OIS3: EVIDENZE GEOARCHEOLOGICHE DALLA PIANA DI COLFIORITO (APPENNINO CENTRALE)

Abstract

Giaccio B. (et al.), Geoenvironmental and human response to the sub-orbital climatic oscillations of the OIS3: geoarchaeological evidence from the Colfiorito Plain (central Italy). (IT ISSN 0394-3356, 2004).
The Colfiorito Plain is a Plio-Quaternary tectono-karstic intermontane basin of the Central Apennines, located at ~750 m a.s.l. A large
excavation was recently made across the Fonte delle Mattinate (FDM) saddle, an important mountain pass along one of the main natural way of the region connecting the Tyrrhenian and Adriatic side. Combined, litho-pedostatigraphic and archaeological analyses
describe a detailed geoenviromental evolution and correlated human occupation history of this strategic area in the course of the last
Bond cycle of the Oxygen Isotope Stage 3 (OIS3; ca. 38-29 GISP2 ka B.P.). The lowest part of the succession is related to a fluvial
depositional system, represented by an active channel and an adjacent floodplain which was in turn subjected to overbanking episodes
and pedogenetic processes testified by an evolved paleosol (Vertisol) dated to 31.510±860-30.970±310-28.910±390-28.300±790 14C
yr B.P. The paleosol is buried by a thick sequence of gravely silty sediments ascribable to debris-flow-dominated fan depositional
system. Radiocarbon dates from the base and top of this unit place the this environmental shift between 25,930±325 B.P. and
24,150±120 B.P. The paleosol and the two silty levels at the base of the alluvial fan sediments yielded Early Upper Palaeolithic artefacts
and associated features consistent with brief, but frequent episodes of human occupation. The available stratigraphic and radiocarbon
data indeed indicate that human occupation at FDM area was probably systematic, and lasted the whole period of the soil formation
up until the first alluvial episodes responsible for its burial. In terms of the radiocarbon chronology, this period spans at least the interval between 31,510±860, age of the oldest anthropogenic charcoals embedded in the paleosol, and 25,930±325, date of the uppermost documented archaeological layer of the sequence. The site being definitively abandoned after this latter date. Based on lithostratigraphic data and chronology the FDM paleosol has been correlated with a pedomarker well documented throughout Central Apennine.
Furthermore, regional pollen information and tephrochronological data suggest that the formation of both FDM and Central Apennine
paleosol(s) occurred during a mild and wet climatic phase corresponding to the firsts millennial of the last Bond cycle of the OIS3
(Greenland interstadial 8-7; ca. 38-34 GISP ka B.P. The subsequent co-occurrence of geoenvironmental change and human abandonment can be correlated with the Heinrich event 3 (HE3; ca. 30-29 GISP2 ka B.P.), the last coldest episode of the above mentioned Bond cycle. Such site evidence for synchronous geoenvironmental and human responses to the HE3, suggests that during the OIS3 the environmental changes related to the HEs had a significant impact on Palaeolithic communities, probably limiting or modifying their mobility in the Central Apennine mountains.