Muck from the bottom of an Irish lake has captured the interest of 15 European research laboratories which are using it to read the details of 11,000 years of environmental history.
The otherwise unpromising-loo king sludge is like gold for the scientists, who are gaining information about climate, local plant growth and evidence of early farming on the Atlantic seaboard.
The two-year EU-funded project, now in its second year, is being co-ordinated at NUI Galway by Prof Michael O'Connell of the palaeo-environmental research unit in the Department of Botany. It involves researchers in Finland, Germany and Switzerland, with seven main contractor laboratories, explains Prof O'Connell.
The focus of all the attention is a sediment core extracted from An Loch Mor, a 23m-deep lake on the smallest of the Aran Islands, Inishere. Part of the lake bed sediments in An Loch Mor, which reach down 14 metres, are known as being "varved", Prof O'Connell says. "It is like tree rings in the sediment."
A varved sediment shows distinct physical and chemical layering which mark the passage of summer and winter. Varving is common in Scandinavian lakes because of the strong seasonality but doesn't happen so much here.
An Loch Mor is particularly deep, however, which has meant that there was little lake bed disturbance over the years and the sediments laid down by centuries of lake-dwelling plants and microscopic organisms remained relatively untouched. "We have material back to 15,000 years ago but that is referred to as the late glacial. This project is on the Holocene, the present warm period." The top 12 metres of sediment taken in the core offer this 11,000-year window on the past, from the time that the great glaciers which blanketed Europe were in retreat.
There is a wealth of information in the sediment if you know what to look for. Fossil pollen, NUI Galway's particular speciality, tells us what was growing on Inishere; precipitated calcium carbonate, produced by the growth of algae, tells us about temperatures and growth conditions.
The shells of a tiny bivalve, ostracod, tell us about water temperature and water conditions. There is also exotic micro-chemical analysis of oxygen isotope ratios that gives information about temperature.
Those familiar with the treeless topography of the Aran Islands might be surprised to know that only a few thousand years ago, Inishere was covered with trees, particularly oak, pine, elm, hazel, alder, birch and willow and then, later on, yew. "We have sketched out an 11,000-year record of pollen" Prof O'Connell says.
Most of the pollen recovered during the first half of the Holocene was from trees. "We not only counted the pollen but in the sediments as well are pine stomata. These are remnant parts of pine needles which would have blown or dropped into the lake. We can be absolutely certain that pine was growing up to about 2,000 years ago."
The top two metres of sediment includes rye pollen, an indication of early farming on Inishere and a crop grown to this day. "We have clear evidence of Neolithic farming activity on the island," Prof O'Connell said.
The idea for the project arose from work being done by NUI Galway pollen expert Dr Karen Molloy, who was studying sediments in east Clare. She has been identifying and counting pollen and other microfossils in the Aran sediment including fungi, algae and microscopic animals.
University College Dublin's Department of Geology is also involved in the work. Dr Frank Mc Dermott is using advanced uranium thorium dating techniques to date the plant-derived calcite in the sediment.
The chemistry of the sediments is being studied in Potsdam and the Department of Physics in the University of Bern is investigating the oxygen and carbon isotope ratios. The Finnish Geological Survey in Helsinki is examining the varve structure and pattern.
"In this project, present-day ecological conditions are also being studied in NUI Galway using resources drawn from the departments of botany, applied geophysics and zoology," Prof O'Connell says.