New laboratory experiments exploring likely subglacial conditions reveal controls on the transition between stable sliding and stick-slip motion of debris-laden ice over rock, with implications for glacier behavior. Friction between a rock substrate and clasts in ice generates heat, which melts nearby ice to produce lubricating water. An increase in sliding speed or an increase in entrained debris raises heat generation and thus meltwater production. Unstable sliding is favored by low initial lubrication followed by rapid meltwater production in response to a velocity increase. Low initial lubrication can result from cold or drained conditions, whereas rapid increase in meltwater generation results from strong frictional heating caused by high sliding velocity or high debris loads. Strengthening of the interface (healing) during “stick” intervals between slip events occurs primarily through meltwater refreezing. When healing and unstable sliding are taken together, the experiments reported here suggest that stick-slip behavior is common from motion of debris-laden glacier ice over bedrock.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.