Nick Marriner

Rapid sea-level movements and noneruptive crustal deformations in the Phlegrean Fields caldera, Italy

The importance of Pozzuoli9s archaeological ruins in linking sea-level change and Earth deformation with volcanic activity has been recognized since the nineteenth century. The pillars of the Roman market were used as a paleotide gauge by pioneer geologists such as Lyell. For the first time, we have radiocarbon dated biological indicators on these remains, showing three 7 m relative sea-level highstands during the fifth century A.D., the early Middle Ages, and before the 1538 eruption of Monte Nuovo. These repeated uplift and subsidence cycles, not always followed by volcanic activity, have important implications for the evaluation of volcanic hazard.

Nile Delta’s sinking past: Quantifiable links with Holocene compaction and climate-driven changes in sediment supply?

The Nile Delta is a subsiding sedimentary basin that hosts ~66% of Egypt’s population and 60% of the country’s food production. Projected sea-level-rise scenarios for the coming decades have sharpened focus on the delta’s potential resilience to rapid changes in accommodation space. We use chronostratigraphic data from 194 organic-rich peat and lagoon points to quantitatively reevaluate the drivers of Nile Delta surface dynamics during the Holocene. Reconstructed subsidence rates range from 0.03 to 4.5 mm/yr, and are highest in the Manzala, Burullus, Idku, and Maryut lagoons, areas that correspond to deep late Pleistocene topography infi lled with compressible Holocene strata; 88% of the subsidence values are <2 mm/ yr. We suggest that during the Holocene two signifi cant but previously underestimated contributors to changes in Nile Delta mass balance have been sediment compaction and orbitally forced changes in sediment supply. Between 8000 and 4000 calibrated (cal) 14 C yr B.P., spatially averaged sedimentation rates were greater than subsidence, meaning that delta aggradation was the dominant geomorphological process at the regional scale. Since ca. 4000 cal yr B.P., a sharp climate-driven fall in Nile sediment supply, coupled with the human-induced drainage of deltaic wetlands, has rendered the depocenter more sensitive to degradation by sea-level rise and extreme fl ood events.

Geoscience rediscovers Phoenicia's buried harbors

After centuries of archaeological debate, the harbors of Phoenicia9s two most important city states, Tyre and Sidon, have been rediscovered, and including new geoarcheological results reveal how, where, and when they evolved after their Bronze Age foundations. The early ports lie beneath their present urban centers, and we have indentified four harbor phases. (1) During the Bronze Age, Tyre and Sidon were characterized by semi-open marine coves that served as protoharbors. (2) Biostratigraphic and lithostratigraphic data indicate the presence of early artificial basins after the first millennium B.C. (3) The harbors reached their apogees during the Greco-Roman and Byzantine periods. (4) Silting up and coastal progradation led to burial of the medieval basins, lost until now.

Tracking Nile Delta vulnerability to Holocene change.

Understanding deltaic resilience in the face of Holocene climate change and human impacts is an important challenge for the earth sciences in characterizing the full range of present and future wetland responses to global warming. Here, we report an 8000-year mass balance record from the Nile Delta to reconstruct when and how this sedimentary basin has responded to past hydrological shifts. In a global Holocene context, the long-term decrease in Nile Delta accretion rates is consistent with insolation-driven changes in the ‘monsoon pacemaker’, attested throughout the mid-latitude tropics. Following the early to mid-Holocene growth of the Nile’s deltaic plain, sediment losses and pronounced erosion are first recorded after ~4000 years ago, the corollaries of falling sediment supply and an intensification of anthropogenic impacts from the Pharaonic period onwards. Against the backcloth of the Saharan ‘depeopling’, reduced river flow underpinned by a weakening of monsoonal precipitation appears to have been particularly conducive to the expansion of human activities on the delta by exposing productive floodplain lands for occupation and irrigation agriculture. The reconstruction suggests that the Nile Delta has a particularly long history of vulnerability to extreme events (e.g. floods and storms) and sea-level rise, although the present sediment-starved system does not have a direct Holocene analogue. This study highlights the importance of the world’s deltas as sensitive archives to investigate Holocene geosystem responses to climate change, risks and hazards, and societal interaction.

Ancient harbour infrastructure in the Levant: tracking the birth and rise of new forms of anthropogenic pressure.

Beirut, Sidon and Tyre were major centres of maritime trade from the Bronze Age onwards. This economic prosperity generated increased pressures on the local environment, through urbanization and harbour development. Until now, however, the impact of expanding seaport infrastructure has largely been neglected and there is a paucity of data concerning the environmental stresses caused by these new forms of anthropogenic impacts. Sediment archives from Beirut, Sidon and Tyre are key to understanding human impacts in harbour areas because: (i) they lie at the heart of ancient trade networks; (ii) they encompass the emergence of early maritime infrastructure; and (iii) they enable human alterations of coastal areas to be characterized over long timescales. Here we report multivariate analyses of litho- and biostratigraphic data to probe human stressors in the context of their evolving seaport technologies. The statistical outcomes show a notable break between natural and artificial sedimentation that began during the Iron Age. Three anchorage phases can be distinguished: (i) Bronze Age proto-harbours that correspond to natural anchorages, with minor human impacts; (ii) semi-artificial Iron Age harbours, with stratigraphic evidence for artificial reinforcement of the natural endowments; and (iii) heavy human impacts leading to completely artificial Roman and Byzantine harbours.

Solar pacing of storm surges, coastal flooding and agricultural losses in the Central Mediterranean

Storm surges, leading to catastrophic coastal flooding, are amongst the most feared natural hazards due to the high population densities and economic importance of littoral areas. Using the Central Mediterranean Sea as a model system, we provide strong evidence for enhanced periods of storminess leading to coastal flooding during the last 4500 years. We show that long-term correlations can be drawn between storminess and solar activity, acting on cycles of around 2200-yr and 230-yr. We also find that phases of increased storms and coastal flooding have impacted upon mid- to late Holocene agricultural activity on the Adriatic coast. Based on the general trend observed during the second half of the 20th century, climate models are predicting a weakening of Mediterranean storminess. By contrast, our new data suggest that a decrease in solar activity will increase and intensify the risk of frequent flooding in coastal areas.

Holocene morphogenesis of Alexander the Great's isthmus at Tyre in Lebanon.

In 332 B.C., Alexander the Great constructed an ≈1,000-m-long causeway to seize the offshore island of Tyre. The logistics behind this engineering feat have long troubled archaeologists. Using the Holocene sedimentary record, we demonstrate that Alexanders engineers cleverly exploited a shallow proto-tombolo, or sublittoral sand spit, to breach the offshore citys defensive impregnability. We elucidate a three-phase geomorphological model for the spits evolution. Settled since the Bronze Age, the areas geological record manifests a long history of natural and anthropogenic forcings. (i) Leeward of the island breakwater, the maximum flooding surface (e.g., drowning of the subaerial land surfaces by seawater) is dated ≈8000 B.P. Fine-grained sediments and brackish and marine-lagoonal faunas translate shallow, low-energy water bodies at this time. Shelter was afforded by Tyres elongated sandstone reefs, which acted as a 6-km natural breakwater. (ii) By 6000 B.P., sea-level rise had reduced the dimensions of the island from 6 to 4 km. The leeward wave shadow generated by this island, allied with high sediment supply after 3000 B.P., culminated in a natural wave-dominated proto-tombolo within 1–2 m of mean sea level by the time of Alexander the Great (4th century B.C.). (iii) After 332 B.C., construction of Alexanders causeway entrained a complete anthropogenic metamorphosis of the Tyrian coastal system.

Climate change and water management in the biblical city of Dan

Past climate shifts in water-stressed areas show that stagnant water could be a health threat in the context of global change. Global climate change has sharpened focus on the social and economic challenges associated with water deficits, particularly in regions where anthropogenic demands exceed supply. This modern condition was also experienced by the people of ancient western Asia, where chronic water shortages were accentuated by recurrent droughts. However, human societies may react to climate change, particularly desiccation, in different ways depending on specific local conditions. Focusing on the biblical site of Tel Dan (present-day Israel), we show the effects of severe precipitation decline in an environment that was well watered and fertile even in times of drought. Such local niches of prosperity became attractive targets for predation when food resources became scarce in surrounding rain-fed areas. We propose that predation forced urban populations to either flee or adopt new subsistence strategies. Predation and abandonment, even if only partial, led to the poor maintenance of water networks in and around the city. Once stagnant water surrounded the area, water-borne disease proliferated. Our study shows how climate changes can disrupt social and political structures, cause water system management to collapse, and facilitate marshland expansion.

A Geomorphological Reconnaissance of Tromelin Island, Indian Ocean

Abstract Marriner, N.; Pirazzoli, P.A.; Fontugne, M.; Geérout, M.; Guillaume, M.M.M., and Reyss, J.L., 2012. A geomorphological reconnaissance of Tromelin Island, Indian Ocean. Tromelin is a small coral reef island (∼1 km2) located in the Indian Ocean, approximately 440 km E of Madagascar and 580 km N of La Réunion. Despite the presence of a permanent Météo France weather station on Tromelin since the 1950s, a detailed geomorphological study of the island has never been undertaken. In this paper, we describe the geomorphology of the atoll, detailing seven geomorphological zones from the outer reef to the atoll crown. We also discuss Holocene relative sea-level changes in the light of new radiometric datings. Uranium–thorium dating of a remnant mid-Holocene reef-flat yielded an age of 5700 ± 400 years and could be interpreted as a relative sea level approximately 1.2 m above present. Subsequent possible sea-level positions have been inferred from coral conglomerates left by high-energy waves. These conglomerates might be interpreted as a beachrock, cemented mainly in the former intertidal zone when sea level was still approximately 1.2 m above present. The radiocarbon dating of three coral fragment samples collected from these conglomerates has yielded ages spanning 4200 to 2900 calibrated years BP.

Holocene evolution of Portus Pisanus, the lost harbour of Pisa

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.