Rock creeps… very slowly. Dave Prior describes the motion as gloopy … He’s had his 200 and 300 level students experimenting, using ice as a proxy for rock and the ice creep experiments ran over two weeks.
“ We put together 10 sets of low cost equipment, taking cylinders of ice and putting them under constant load then measuring the deformations in the structure. Students worked in groups, coming in through the night to take readings and we ran the experiments over two weeks. While this experiment is not novel in ice research, doing so many at once provides a large data set for this particular research area.”
The students really appreciated that this work had never been done as a class experiment before, and an international expert said the results were excellent. Professor Prior says this experimental approach delivered much better learning about rock and ice flow, than theoretical coverage alone would achieve. It’s a class experiment he will definitely repeat.
So what did the students see in their squeezed ice? Crystal images show how the structures started off with crystals of uniform shape, but all over the place in terms of orientation. After the experiment, the crystals were non-uniform in size, and were much more strongly aligned. The ice at the bottom of an ice sheet will be deformed, in the same way their cylinders of ice were.
These deformations demonstrate what happens with rocks too – creeping slowly in a gloopy kind of way …