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This item was submitted to Loughborough’s Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions. For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ Reconstructing the Holocene coastal development of the Laurentine Shore by Andrew Robert Bicket A Doctoral Thesis Submitted in partial fulfilment of the requirements for the award of D. Phil of Loughborough University October 2009 © by Andrew Robert Bicket 2009 Abstract The 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. Keywords Geoarchaeology, geochronology, petrology, provenance, diagenesis, Tiber Delta, coastal dune ridges, Holocene, Castelporziano, Laurentine Shore iv Acknowledgments Technical support from Mark Szegner (Lboro Geography), David Twigg (Lboro Civil Eng.), Al Daley (Lboro Chemistry), David Townrow (Wolverhampton), and David Alderton and Inga Sevastjanova (Geology RHUL) made various aspects of this thesis possible. Dave Ryves, Jon Lewis, Keely Mills and Kaarina Weckström are thanked for valuable ideas and discussion regarding all things diatom. Grateful acknowledgment is made to Chris, Tim, Peter, James, Ginny, Michele and Liz for invaluable fieldwork assistance and for making the long hours of excavation and surveying a pleasure rather than a chore. Professors Amanda Claridge and Helen Rendell are thanked for their support, encouragement and insight for instigating the project, providing me with an opportunity. Helen Rendell and Joanna Bullard are also thanked for their supervision and expertise. Many thanks are due to the excellent cohort of post-grads at Loughborough University, Dept of Geography and international colleagues I’ve come to know. Their good humour and support manifested as beer, curry (and occasionally hiking) will continue to be greatly appreciated. The support and encouragement of my parents, who are unlikely to recoup their long-term financial investment in my never-ending education, is gratefully acknowledged. They are thanked for never asking when I’m getting a ‘proper job’. Emma is humbly thanked for her support, for persevering and for keeping me laughing; cheers, hon. “The particle. Very difficult to measure the particle. To measure it you must shine light upon it, but by doing so you distort the image of the particle making it impossible to take an accurate reading. I used smaller and smaller amounts of light, but still to no avail. Eventually I used the smallest amount of light known to man – the glove box light of a 1974 Austin Maxi.” (Bailey, B., 2004) v Table of Contents Abstract ................................................................................................................................................................................. iii Keywords ............................................................................................................................................................................... iv Acknowledgments .................................................................................................................................................................. v List of Figures ........................................................................................................................................................................ xv List of Tables ....................................................................................................................................................................... xviii List of Plates .......................................................................................................................................................................... xx 1. Introduction .................................................................................................................................................................... 1 1.1. La Tenuta di Castelporziano ....................................................................................................................................... 1 1.2. Research at Castelporziano ........................................................................................................................................ 3 1.2.1. The Laurentine Shore Project ............................................................................................................................. 4 1.3. Aim .............................................................................................................................................................................. 5 1.4. Objectives ................................................................................................................................................................... 5 1.4.1. To examine the processes affecting the coastal development of the site during the Holocene ....................... 5 1.4.2. To examine the chronological development of the landscape, principally by dating coastal dune ridges, sand sheets and archaeological sites .......................................................................................................................................... 6 1.4.3. To examine how the geoarchaeology of the Laurentine Shore is driven by macro-, and meso-scale processes of relative sea level change, delta progradation and key anthropogenic factors .............................................................. 6 1.5. Research Questions .................................................................................................................................................... 6 1.5.1. How has the coastline of the Laurentine Shore developed during the Holocene? ............................................ 6 1.5.2. What are the processes of coastal development acting on the Laurentine Shore? .......................................... 6 1.5.3. What is the chronology of these coastal changes? ............................................................................................ 6 1.5.4. What are the key interactions between anthropogenic and geomorphological processes? ............................ 6 1.5.5. What are the benefits of a multi-scale geoarchaeological approach and the implications for future research? 6 1.6. Theoretical models ..................................................................................................................................................... 6 1.6.1. Geomorphological model ................................................................................................................................... 7 1.6.1.1. The study of sand dunes ............................................................................................................................