How cold was it? Glaciers in New England?

I was very, very pleased to receive this comment by Bob (a physical geographer by ‘trade’) a bit more than a week ago. Bob posted the comment on my blog about Point Lookout and has been reproduced below:

"Rod,

You and your readers might be interested in a discovery made around Ebor and Guyra just last week, when I was working with a team of glacial buffs from UQ and UT. We found definite evidence of periglacial activity, presumably from the Last Glacial Maximum, ~20 000 years ago. The best examples were at Guyra on the slopes around Malpas Dam -- clear evidence of solifluction lobes, rock glaciers, snow hollows, and other freeze-thaw features, and what could only be described as incipient cirques -- ponds and bogs sapping back into the escarpment and probably still holding some snow in the frigid Guyra winters. The curious point is that they were between 1200 and 1300 metres, not at the highest points above 1500m where we were expecting them, but all on steep south facing escarpments.

One intriguing feature near Point Lookout, on the road up where it crosses the Little Styx River and at 1450m, was what looked very like a terminal moraine. This of course is a glacial, not a periglacial feature, so it is very hard to believe-but have a look at it, and see what you can make of it. There were at least 16 glacial cycles in the Pleistocene, so maybe one of them at least was really severe, and glaciated this far north. Otherwise, you have to go back to the Permian...

Bob H."


probable solifluction lobes and terraces on hill slope at Malpas Dam

This is exciting stuff to hear about because to my knowledge there is little or no evidence of cold climate landforms in the region. In fact I think the areas of the Tasmania are probably the only areas in Australia were these are frequent, though they have also been possibly identified in the Southern Alps and areas of Victoria. Certainly authors such as Petherick et al. (2011) and Hope (2005) did not identify such equivalent indicators of how far north such extreme cold could be detected. I understand that the cold climate landforms that Bob mentions have been found by researchers various universities such as from the University of Queensland, University of Technology, Sydney and the University of Tasmania. Acting on the tip off from Bob, I found an example of solifluction right on the northern side of Malpas Dam using Google Maps, this one is actually visible from the lookout on the southern side of the dam too (sorry about the quality of the photos, it was a long time since I took them and I didn’t realise what I was looking at that time). Get on Google maps and visit the dam yourself and have a look.


Same solifluction lobes visible south of the hill (same hill as picture above)

Solifluction is caused from the thawing of surface layers of permafrost during the summer leading to the thawed part of the soil profile slipping over the un-thawed permafrost and creating ‘lobes’ of soil. The cold climate structures that have been identified near Guyra are present on the southern side of the hill slopes where the sun was unable to melt much of the ice in the soil and therefore creates conditions of permafrost. Permafrost is not present anywhere on the Australian mainland today and demonstrates a significant change in climate has occurred (though those that know Guyra will still argue it is still uncomfortably cold there!).

What Bob appears to have found near point lookout is even more incredible, as a moraine is formed through the action of glaciers which are accumulations of ice on the surface that slowly moves through a landscape under the action of their own weight. Glaciers in Australia were thought to be limited to Tasmania and the Snowy Mountains. No doubt we will expect to see some published papers on the structure and context of these cold climate features in the region some time in the near future. I can't wait to read the published work that comes from this discovery. 

For further information on the individual cold climate features described above by Bob  visit the glossary, an online encyclopeadia or a good physical geography book such as Geosystems by Christopherson. If you are a little unclear about the locations of these sites and how they fit into a ‘Northern Rivers’ blog then it is worth mentioning this part of the New England, at Guyra and Malpas Dam are right at the head waters of the Gara River which is a tributary of the Macleay River that runs through Kempsey. The New England Highway in the Guyra area is pretty close to the actual crest of the catchments of the northern rivers, with the rivers to the west of it flowing into the Murray-Darling Basin and those to the east to the Pacific Ocean. Point Lookout is in the headwaters of the Bellinger River which runs trough Bellingen and is also part of the headwaters of the Macleay too.

References/Bibliography:

*Christopherson, R.W., 1997. Geosystems Wiley.
*Hope, P. 2005. The Weather and Climate of Australia During the Last Glacial Maximum. University of Melbourne, PhD Thesis, unpubl.
*Petherick, L.M., Moss, P.T & McGowan, H.A., 2011. Climatic and Environmental Variability During the Termination of the Last Glacial Stage in Coastal Eastern Australia: A Review. Australian Journal of Earth Science V.58.