Holocene evolution of Portus Pisanus, the lost harbour of Pisa

Abstract

The ancient harbour of Pisa, Portus Pisanus, was one of Italy’s most influential seaports for many centuries. Nonetheless, very little is known about its oldest harbour and the relationships between environmental evolution and the main stages of harbour history. The port complex that ensured Pisa’s position as an economic and maritime power progressively shifted westwards by coastal progradation, before the maritime port of Livorno was built in the late 16th century AD. The lost port is, however, described in the early 5th century AD as being “a large, naturally sheltered embayment” that hosted merchant vessels, suggesting an important maritime structure with significant artificial infrastructure to reach the city. Despite its importance, the geographical location of the harbour complex remains controversial and its environmental evolution is unclear. To fill this knowledge gap and furnish accurate palaeoenvironmental information on Portus Pisanus, we used bio- and geosciences. Based on stratigraphic data, the area’s relative sea-level history, and long-term environmental dynamics, we established that at ~200 BC, a naturally protected lagoon developed and hosted Portus Pisanus until the 5th century AD. The decline of the protected lagoon started at ~1350 AD and culminated ~1500 AD, after which time the basin was a coastal lake.

Anthropogenic Impact on Beach Heterogeneity within a Littoral Cell (Northern Tuscany, Italy)

“…Significant modifications of the coastal area related to anthropogenic activities occurred since the bronze age about 3000 years ago, when widespread inland deforestation commenced [80][81][82]. The drastic increase of sedimentary supply and the stabilization of the sea level rise [83,84] caused a strong acceleration in the rate of coastal progradation, which resulted in the development of a wide coastal plain. This seaward shift of the coastal system is recorded by the juxtaposition of several outcropping beach ridges roughly oriented parallel to the coastline and, in the subsurface, by the sharp transition from a lagoon to shallow marine deposits [85].…”

Halmyris: Geoarchaeology of a fluvial harbour on the Danube Delta (Dobrogea, Romania)

“…These lowlands at the land–sea interface were particularly attractive, since the stabilisation of sea-level around 6000 yr BP, because they provided fertile lands for agriculture and a permanent freshwater supply, as well as access to the hinterland by fluvial routes. A multi-proxy approach allows to clearly identify the environmental pressures that affected deltaic harbour cities and to highlight the adaptation of populations, including, for instance, Alexandria (Nile delta: Flaux et al, 2017; Goiran et al, 2005), Miletos (Büyük Menderes delta: Brückner et al, 2006, 2014), Ephesos (Küçük Menderes delta: Stock et al, 2013, 2016), Ainos (Maritsa delta: Seeliger et al, 2018), Pisa (Arno and Serchio delta: Allinne et al, 2016; Benvenuti et al, 2006; Kaniewski et al, 2018), the Greek colonies of the Taman Peninsula (Kuban delta: Giaime et al, 2016; Kelterbaum et al, 2011); Aigues-Mortes (Rhône delta: Rey et al, 2016), Ostia (Tiber delta: Goiran et al, 2014; Salomon et al, 2017, 2018) or Utrecht (Rhine delta: Van Dinter et al, 2017).…”

Litho-sedimentological and morphodynamic characterization of the Pisa Province coastal area (northern Tuscany, Italy)

“…In the study area this sandy complex constitutes the outcropping depositional portion of the late Holocene progradational system forming after mid Holocene sea-level stabilization (Kaniewski et al, 2018). Since about 3000 BP, subsurface (Aguzzi et al, 2007;Amorosi et al, 2013) and surface (Carratori et al, 1994) data show the acceleration of coastline seaward migration due to increased sediment supply related to widespread deforestation inland (Kaniewski et al, 2018;Pranzini, 2001) as well as the reduction in the rate of accommodation space creation. This increase seems to occur at the same time in the whole Mediterranean area (Amorosi & Milli, 2001;Anthony, Marriner, & Morhange, 2014).…”

“…Three other streams flow into the sea along the Pisa shoreline (namely Serchio River, Morto Nuovo River, and Scolmatore channel), but they are subordinate to the Arno River's catchment area and its high annual sediment load (Cavazza, 1984). The recent evolution of the Arno River delta is strongly related to increasing human pressure reported in the area during the last millennium (Kaniewski et al, 2018). Progradation of the delta was recorded since 1606, as soon as the mouth was artificially offset to the west to avert major floods inland (Pranzini, 2001).…”