DU researchers have been behind the effort

Sep 16, 2009 01:01 GMT  ·  By

Scientists at the Durham University have devised, for the first time, a model of the British and Irish Ice Sheet, which accounts for the sculpted landscape of northern Britain, but also holds a few surprises. The team discovered that the ice moved in unexpected patterns, and also that these movements left distinctive marks on the land the ices passed over. For instance, they say, the egg-shaped features that can be found throughout the northern parts of the country, known as drumlins, were created as glaciers reversed their flows and retreated back upland as the temperatures increased.

The model spans a period of time between 26,000 to 16,000 years ago, and offers a unique “overprinting” of British glacial landforms. Details of the new investigation, which was funded by the Natural Environment Research Council (NERC), appear in the latest issue of the respected scientific journal Quaternary Science Reviews. The research effort was led by DU Department of Geography expert Dr. David Evans. The size, extent and flow directions of the ice-sheet were carefully determined from analyzing maps of superimposed drumlins, ancient temperature records, as well as through computer models.

The timeline set forth by the model revealed that, during the last glacial minimum, some 21,500 years ago, the BIIS built in areas of the Lake District, Northern England and Scottish Southern Uplands, and then naturally overflowed into the lowlands below. It then proceeded to happily making its way to the Irish Sea. And here is the catch, the DU experts say. Rather than making its way to the water, the ices stopped at Solway Lowlands, and then moved backwards on their initial step, further carving landscape that had just been modified on one side.

“The stereotypical image of Ice-Age Britain is of ice rolling in from the Arctic but this is not an accurate description of what happened. Britain was cold enough for ice to form in the uplands, growing and coalescing to produce an elongate, triangular-shaped dome over NW England and SW Scotland around 19,500 years ago. The Ice sheet then moved downhill, as one would expect. Our findings show that the lowland ice became so thick that it began to move in unexpected ways – the ice moved back uphill from where it originally came. Recession and a series of complex ice flow directional switches took place over relatively short timescales.”

“The Durham model shows that an ice sheet can reverse its flow in a hundred or so years and when this happens, it creates unique features in our landscape. Elongated drumlins and meltwater channels in northern England and southern Scotland provide evidence of this unique phenomenon. The ice sheet had no real steady state but rather was mobile and comprised constantly migrating dispersal centers and ice divides which triggered significant flow reversals. The occurrence of Lake District material in Pennine dry-stone walls is a clear indication that during the last glaciation, ice sheet flow directions were at times reversed.”

Photo Gallery (2 Images)

Newton Stewart drumlins
Meltwater channels & streamlined terrain in Lunedale 3
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