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5th International Conference, Portugal, 2008 – Conference Report


5th International Conference, Portugal, 2008 – Conference Report

A joint INQUA – IGCP 495 Meeting

Joint INQUA – IGCP 495 Meeting

International Geoscience Programme Project 495

Quaternary Land-Ocean Interactions: Driving Mechanisms and Coastal Responses
INQUA Commission on Coastal and Marine Processes

Faro, Portugal

27th October – 1st November, 2008

Conference organiser Tomasz Boski discusses with delegates Holocene environmental changes in the Guadiana estuary

Conference Report

This report describes the fifth annual IGCP Project 495 conference and field meeting, held in Faro and the Algarve region of Portugal in October/November 2008. The meeting was hosted by Dr Tomasz Boski and colleagues at the Centro de Investigação Marinha e Ambiental, Universidade do Algarve. The conference was attended by 59 delegates from 12 countries, and comprised three days of oral presentations, a poster session and three days of field visits to sites on the Algarve and Alentejo coasts.

On the morning of day one Claude Hillaire-Marchel presented a critical review of the widely assumed relationship between the oxygen isotope composition of foraminifera and ocean salinity, Rodolpho Angulo presented preliminary evidence for high wave energy events on the southern Brazilian coast which some of us visited on the 3rd International meeting fieldtrip of IGCP495 in 2005, and Peter Vos detailed a series of very detailed palaeogeographic maps of the Dutch coast over the Holocene which showed dramatic changes in coastline position driven by sea-level changes, sediment supply and human activity. Also in this first morning was a discussion of the affects of future sea-level rise on the coasts of Indonesia, a tectonically active tropical island archipelago likely to be hard hit by the effects of projected future sea-level rise (Wahyoe Hantoro). The afternoon papers focussed on coastal evolution in response to various driving mechanisms, including the development of valley fills in lowstand incised valley systems in SE Australia (Craig Sloss) and the Holocene evolution of part of the Belgian coast (Cecile Baeteman). Antony Long also presented the first sea-level record from West Greenland in the last millennia and discussed implications for the mass balance of the Greenland Ice Sheet during this period.

The second day of papers kicked off with an entertaining retrospective on sea-level research over the past 50 years by Nils-Axel Morner and Dorit Sivan then took us to the Levant Mediterranean coast, showing how archaeological remains can make excellent proxy sea-level indicators. Roland Gehrels gave a stimulating paper that suggested, for the first time, that he can detect a “sea-level fingerprint” from Greenland in salt marsh sea-level records from the last two centuries from around the world. Simon Connor talked about the Holocene evolution of the eastern Black Sea coast and I reinvigorated the flagging crowd with a talk on issues of precision and reliability in the transfer function reconstruction approach.

After lunch on day two we boarded the bus for the first of our field excursions, to the coast between Quarteira and Vale do Lobo to look at the effects of human intervention on the coastline in this area. Groins and jetties built at Quarteira during the 1960s and 1970s have increased coastal erosion at the down-coast Vale do Lobo resort. This stop illustrated the ongoing tensions between retaining economic assets in specific locations (e.g., sandy beaches for tourists) whilst appreciating the need to retain the natural balance of inputs and outputs of the coastline as a whole.

Papers of note on day three included two talks on the sea-level history of the Bay of Biscay, describing recent sea-level changes (Alejandro Cearreta) and the longer term, Holocene history of this area (Eduardo Leorri). Marc Hijma discussed evidence for barrier overstepping during the mid-Holocene on the western Netherlands coast and Geertjan Vis addressing the Holocene evolution of the Tagus estuary, central Portugal.

After lunch the poster session, run by Roland Gehrels and Delminda Moura was a great success, with each presenter allowed 2 minutes to summarise their poster to the assembled throng.

With the formal science part of the meeting over on Day 3, we all looked forward to the field trips, which would take in many of the sites described by presenters over the past 3 days. At the crack of dawn on Thursday morning we were taken to Olhão, close to Faro where a boat took us out into the barrier island system of the Ria Formosa. The weather was clear and bright and we had an excellent view over the salt marsh and sand flat systems within the extensive back barrier environment of the Rio Formosa, which is one of the few cape-shaped back barrier systems in the world. We saw the main navigable entrance to the system, which was artificially opened between 1929 and 1955. The artificial management of this opening has had knock on effects for down-drift barrier islands, such as Cultrata Island, which we visited next. It was really remarkable to see the solidity of the buildings in the village of Cultrata, built on the shifting sands of a barrier island and to consider the potentially transient nature of these coastal features in the face of human interventions. After a visit to the beach at Cultrata we headed back to the boat and some lunch, then took the bus to the second stop of the day, Cacela Velha. This was another barrier lagoon location east of Faro, occupied since Roman times with a defensive fortress overlooking the coast. Historical maps show shifts in the sand islands fronting this coast over time, with the greatest impact caused by the 1755 Lisbon tsunami, which caused the closing of the river-mouth lagoon entrance by sand.

Cliff retreat at Olhos de Água, near Albufeira

The final stop of the day took us to the Guadiana estuary, which forms the border between Portugal and Spain. The estuary is now wide and shallow, although the river palaeovalley is narrow and deep (600m wide and 80m deep at 7km inland). Several deep boreholes have been drilled in the intertidal sediments, showing the evolution of the estuary during the early-mid Holocene transgression and allowing foraminifera-based environmental reconstructions. Interestingly, the morphology of the Guadiana estuary is currently being modified by dams upstream, which prevent almost all fluvial sediment supply from reaching the estuary – a further example of how human intervention is now changing coastal morphology which was previously in equilibrium. A visit to the Castle at Castro Marim gave a great overview of the lower estuary and sunset at the end of the day.

After an excellent meal and night in Faro the following day we headed west along the coast towards Albufeira, with a first stop at Olhos de Água. These red, orange and yellow sandy cliffs are Pliocene and Pleistocene in age, eroded by fresh water springs and fault-driven percolation of rainwater into the dramatic and photogenic gullied and indented coastal scenery of this area. The next stop was Praia do Evaristo close to Galé on the south Algarve coast, where we walked across a raised shore platform dated to older than ~400ka BP, capped by a coarse shelly calcarenite. It is not clear whether the shore platform records a former sea level high stand position. After a swift espresso we headed back onto the bus for the journey to Boca do Rio in the western Algarve. This famous site is a filled estuary with an excellent sedimentary record of the 1755 Lisbon tsunami. Here it is hypothesised that the tsunami wave was c. 11m high and travelled 1km inland. César Andrade lead discussion about the nature of the tsunami deposits, and despite the lack of a JCB to help with excavations, the Dutch crew (Geertjan Vis and Marc Hijma) showed us all how to core the central basin to see the tsunami sediments for ourselves. As a memento of the occasion we were all presented with a small capsule of tsunami sand for our desks at work (“Essence of Tsunami”) to remind us of our visit to the famous site of Boca do Rio.

The final stop of the day was at Cape Sagres, the most westerly point on the southern Algarve coast, where we first saw aeolianite dunes preserved in the cliffs which formed during the late glacial and early Holocene periods, then took a tour of the Cape St. Vincent fortress which afforded great views of the cliffs of the Sagres peninsula, and of fishermen and surfers enjoying the last sunshine of the day. We stayed overnight in Lagos, enjoying the second ‘Gala dinner’ of the trip and a good nights sleep ahead of our journey up the western Portuguese coast on day three.

The final day of the field trip started at the mouth of the Mira estuary in Vila Nova de Milfontes where Maria Conceição Freitas showed us borehole records from the Mira estuary which record changing environmental conditions as rising sea-levels flooded the continental shelf during the Holocene. At the second stop at Ilha do Pessegueiro, Ana Ramos Pereira described the long term evolution of the littoral platform in this area, in particular showing us eolianites and beach facies relating to early and mid Pleistocene high stand conditions on this part of the western Portuguese coast. After lunch we drove north to the Santo André lagoon region, which has been extensively studied by scientists from the Centro de Geologica, Faculdade de Ciências, Universidade de Lisboa to reveal the Holocene history of this marine lagoonal system. We first visited Poços do Barbaroxa where cores from the extensive dune slack environment extend into the Pleistocene, potentially the Eemian interglacial. At the last stop of the day, the Santo André ICN (Instituto da Conservação da Natureza) facility, we saw and touched core material collected from the lagoon region. Maria Conceição Freitas and her students showed detailed and extensive proxy evidence for the infilling of the lagoon during first rising then stable relative sea-level between the early Holocene and present.

The dune slack environment at Poços do Barbaroxa

After a long day of interesting science we returned to Vila Nova de Milfontes for third, but most exceptional Gala dinner hosted by the municipality of Odemira. A late return to Faro concluded our field excursions, and we all fell into bed before heading home on Sunday morning.

Finally on behalf of all the delegates who attended this meeting I would like to thank the conference organisers, Tomasz Boski, Delminda Moura, Duarte Nuno Duarte and colleagues at the Centro de Investigação Marinha e Ambiental, Universidade do Algarve, and colleagues from the Universidade de Lisboa for organising an excellent meeting which combined excellent science with interesting field visits, good food and wine and an superb atmosphere throughout.

This conference was a joint meeting with the INQUA Commission on Coastal and Marine Processes. Further information on IGCP495 “Quaternary Land-Ocean Interactions: Driving Mechanisms and Coastal Responses” can be obtained from the UK National Correspondent, Professor Roland Gehrels (University of Plymouth, e-mail: [email protected])

Dr Sarah A. Woodroffe
Durham University