Asked by Yve
Question:
Hi Bethan,
I work as a natural history presenter on expeditions ships in Antarctica. I talk a lot about the ice but I am having difficulty finding answers to a couple of questions. Can you please help?
In some parts of NW Antarctic Peninsula, the surface of many large glaciers draining the ice cap is changing visually (quite quickly and very dramatically) as the more brittle ice at the surface of the glacier appears to be collapsing. This means the previously highly crevassed surface is being replaced by an extensive and ever expanding layer of glacial rubble. Is this something to do with a changing rate of flow, or some other glacial dynamics? Something to do with a brittle-ductile transition within the glacier?? I would love to know the mechanism involved as it really stands out when looking at the landscape.
Also:
Along much of the coastline we visit, the ice has retreated so it now sits ‘flush’ with the shore and the terminal steep cliff remains. Just off the shore, along several coastlines, and particularly where there is small glacier just reaching in to the water, there is a prominent terminal moraine. This moraine is usually a several tens of metres out from the shore. Do you have any idea how long ago the ice extended to these moraines?
I really hope you can help point me in the right direction for finding answers to thess questions – this has been bugging me for a while.
Many thanks,
YveDear Yve,
Thank you for this interesting question. I consulted with some colleagues on this.
With regards to the rapidly changing glaciers on the Antarctic Peninsula, this is very interesting – could be more fracturing caused by glacier speed up and perhaps also increased steepening of the ice surface.
The moraines are likely dating to the last 1000 years.
Alex Simms published a paper a few years ago about LIA glacial advances on the peninsula (https://www.sciencedirect.com/science/article/pii/S0277379121004029) so that would fit with the last 1000yrs.
There is also a paper from King George island that argues for some late Holocene readvances (https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.1073075/full).
Best wishes
Bethan