Monday, January 29, 2007

Breaking: Revolution in Drumlin formation theory!

Of interest only to those fascinated by all things glacial, which means you, dear reader, the theory of how drumlins form is undergoing radical revision.

Here's your chance to be on the cutting edge of science and the guaranteed life of the next party (if you live in Canada, that is):
A new study threatens to overturn our understanding of how glaciers deposit whale-shaped hills known as drumlins. The findings could have implications for the computer models used to predict glacier flow and subsequent changes in sea-level.

Andy Smith of the British Antarctic Survey and his colleagues are the first to see a drumlin during formation. They have visited the same spot of the Rutford Ice Stream in Antarctica three times since 1991. Each time, they have mapped the shape of the glacier bed, which lies 2000 metres under the surface of the ice. [...]
Using seismic mapping, they found:
[Researcher Vaughan says] "What is surprising is that big lumps of sediment are being moved around wholesale rather than being slowly accumulated."

He says the mass of sediment seems like it is encased in the underside of the ice sheet and being dragged along as the glacier moves towards the sea. [....]
What does this mean? Who knows. My guess, though, is that it means nothing more than drumlins can be formed in more than one way. The old theory holds that drumlins accumulate and grow thanks to large meltwater rivers running under the glacier.

I think a look (impossible at the moment) at the provenance of the rocks making up the drumlin would be instructive. (the Wiki article on drumlins is here)