Thesis-2009-Bicket.pdf (10.38 MB)
Reconstructing the Holocene coastal development of the Laurentine Shore
thesis
posted on 2010-04-26, 08:50 authored by Andrew R. BicketThe Laurentine Shore is the Imperial Roman palaeo-shoreline preserved up to 1km inland of the southern, distal edge of
the Tiber Delta coastline of Lazio, western Central Italy. The progradation of the delta is recorded on the site as a series
of shore-parallel relict dune ridges. High-status villas developed along the roman period coastline, with a service village
(Vicus Augustanus), and other infrastructure such as roads, aqueduct, piscinae and several baths (thermae), these
structures have been examined using a multi-scale geoarchaeological approach.
A sea level reconstruction based on multi-proxy palaeo-environmental analysis of a silt/peat sedimentary transition
from the base of a Roman piscina suggests that the sea level at ca. 2400 ± 40 BP was around 1.25 ± 0.2 m below modern
sea level. This analysis provides further context for assessing the development of the site during the late Holocene in
relation to the progradation of the Tiber delta and for the important Imperial Roman period occupation of the
Laurentine Shore and other important sites such as Portus and Ostia Antica in the central part of the Tiber delta.
At several key periods in the late Holocene, the palaeo-shoreline has been reconstructed using a geochronological
framework of optical luminescence dates and geomorphological survey of the Tiber Delta dune ridge record. In
particular, during the Imperial Roman period, ca. 2000 BP) it has been shown that the Laurentine Shore was settled
during a period of significant Tiber delta shoreline progradation. Two-major building phases at the Vicus Augustanus
occur within this progradation phase. By the abandonment of the site in the 5th century AD, the shoreline was around 70
m seaward of the shoreline during the 1st building phase of the Vicus. This rate of shoreline change could be noticeable
by the population over decadal timescales and may have driven the alteration of coastal building and property plots
during the 500 year lifetime of the settlement.
A combined methodology incorporating sedimentology, geochemistry and petrological analysis of diagenetically altered
sediments found that early vadose diagenesis may have a deleterious effect upon luminescence dating dosimetry,
inducing age underestimation, especially of reddened dune sands. Petrological analysis has also shown that a lack of
anomalous fading in luminescence behaviour observed in K-feldspars may be due to a lack of complex microstructure in
the mineral grains driven by the metamorphic, Alpine origin of these minerals.
An assessment of the geoarchaeological approach used in this thesis shows that a scale-driven context provides a useful
structure for examining the various processes and factors affecting the geomorphological and sedimentological records
improving confidence in the examination of the archaeological record.
History
School
- Social Sciences
Department
- Geography and Environment