The Samoan Lakes Project
Aleni Fepuleai, Kirti Lal, Conway Pene and Stephen Gale
Time: 11-12 noon
Venue: M107 Lecture Theatre, Marine Campus
A team from the School of Geography, Earth Science and Environment recently spent several weeks in Samoa searching for sedimentary records of environmental change, volcanic history and human environmental impact. The team’s target was the volcanic crater lakes that pepper the Samoan landscape. A distinctive feature of these lakes is that they are entirely closed, with no drainage outlet. As a result, they trap and retain the depositional products of just about every event that takes place within their catchments. The resultant sediments retain a wide range of environmental signals: clues to the timing of human arrival, evidence of shifts in vegetation cover, records of changes in water chemistry, histories of the fallout of volcanic ash and much else.
To gain access to these records, we needed to be able to extract long undisturbed cores of sediment from the lakes. Working in remote locations such as this required gear light enough to pack into the site on foot, with the capacity to extract cores of up to ten metres in length from water depths of over five metres, and sufficiently robust to survive the rigours of remote area fieldwork. To meet these needs we designed and built a set of equipment entirely from scratch, deliberately making use of consumables (such as tubing for the core barrels) that are freely available around the Pacific.
The aims of the project are threefold. First, sediment cores obtained from the lake will be used to establish a reliable event chronology for Samoa during Holocene times based on tephra stratigraphy. This will provide a framework for subsequent studies of Holocene environmental changes and human impact across the islands.
Secondly, we aim to use this chronology to understand the nature and pattern of volcanism in the islands during the last several thousand years. This will yield baseline data that will be of value both to government organisations and scholarly research. It will provide a chronology of recent and past volcanic activities and will allow an assessment of volcanic hazard. This will improve the capacity of official organisations to respond to and manage natural disasters.
Thirdly, the sedimentary record provides an opportunity to investigate the human colonisation of the islands and human impacts on previously undisturbed environments. Earlier archaeological work on the islands has been confined to individual sites and may not offer continuity of record. These may miss the evidence of first contact and may provide only incomplete records of human impact. By contrast, a stratigraphic approach to the acquisition of palaeoenvironmental information provides an opportunity to establish the nature of the pre-contact environment and the timing and magnitude of human impacts.
