Palaeo-Caribbean

July 30, 2013
WDG

Earlier this month Rachel Gwynn (Geography, UCL) visited the PCRG to use our core splitter to reveal what was contained within two cores collected from the Carribean. She has also been kind enough to provide photos of the sediments and an insight into the story so far:

Sediments from Fresh Water Pond Barbuda (Photograph Rachel Gwynn)

Sediments from Fresh Water Pond Barbuda (Photograph Rachel Gwynn)

Lake sediment cores covering the past few hundred to thousand years have been taken from two lakes, Wallywash Great Pond in Jamaica and Freshwater Pond in Barbuda. The sediments form part of the NERC-funded project Neotropics1k (PI Prof. Jonathan Holmes), which is concerned with climate variability in the northern Neotropics over the past millennium. The sediment cores show marked changes in composition and colour, from pale marl to dark organic mud. These colour changes, which are clearly visible in the photographs, represent changes in sediment composition that are in turn related to lake-level variations caused by long-term climate shifts. Deeper, open-water conditions under wetter climate are represented by the marls, whereas lowered lake levels, caused by direr climate, are associated with organic-rich sediments.

Wallywash Great Pond– core section W2

  • Thirteen separate units have been identified through the 1 m core length, varying between light coloured marl, dark organic and shelly sediments.
  • The abundance of preserved Ostracod valves increases throughout the marl and shell rich layers but drops significantly in the organic rich material.

Barbuda Freshwater Pond- core section FWP

  • This core has four distinct units. 0-23 cm is a calcareous mud with a diffused lower boundary into a shelly calcareous mud at 25-35.5 cm. 35.5-38 cm and 38-52 cm is two variations of calcareous mud.
  • These units, as with the W2 core, have been defined using a Munsel Soil Chart.
  • The Ostracod valves are thought to be abundant throughout the core due to the high marl content.
Wallywash Great Pond Jamaica (photograph Rachel Gwynn)

Wallywash Great Pond Jamaica (photograph Rachel Gwynn)

PCRG March

April 12, 2013
WDG

Rachel Gill and Encarni Montoya with sediment cores from Jamaica.

Rachel Gill and Encarni Montoya with sediment cores from Jamaica.

Quick and belated update on activity in March! Not sure where the time is going at the moment…

Early in the month we were delighted to welcome Prof. Jonathan Holmes and Rachel Gill from UCL who came to use our core splitter to open new sediment cores from Wally Wash Pond in Jamaica! A visit from Steve Brooks (Natural History Museum) early in the month to discuss midgy progress with Frazer was great. We are getting ever closer to developing a training data set… Also popping by was ex-PhD student and now Aberystwyth lecturer Joe Williams who we will hopefully be developing some new collaborations with over the summer and fingers crossed mounting an expedition back to Bolivia!

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Reconstructing environmental change in Jamaica

July 23, 2012
WDG

by Mick Burn and Suzanne Palmer (University of West Indies)

Our whistle-stop tour of the UK brought us to the PCRG on the 26-27 June. We are undertaking a multiproxy (ostracods, gastropods, forams) study of different coastal lagoons along the south coast of Jamaica in order to reconstruct coastal environmental change over the last Millennium. Jamaica lies not only within the firing line of Atlantic tropical cyclones but also forms part of the Gonave microplate, which has been responsible for a series of large earthquakes within the region, including the infamous 2010 earthquake in Port au Prince, Haiti. As a consequence, one of our main challenges is to distinguish between sediments deposited during abrupt climatic and tectonic events over the last ca. 1000 years.

Figure 1: A section of the sediment record from Albion Ponds.

Figure 1: A section of the sediment record from Albion Ponds.

The purpose of our UK visit this year was to split cores recovered from Albion Ponds in preparation for ITRAX XRF core scanning at Aberystwyth University in August. We are very grateful for the hospitality at PCRG and look forward to developing further collaboration on projects in the very near future.

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