Re: Ice Sheets

David Campbell (
Mon, 1 Dec 1997 16:23:43 -0400

>At 12:08 PM 11/26/97 +1100, W. G. wrote:
>>In mainland Australia we have only very limited Quaternary ice deposits
>>which are in the Mount Kosciusko area of New South Wales but I have seen,
>>near Bacchus Marsh in Victoria, Permian tillites (glacial deposits) and
>>other evidence of glaciation. These show of a number of glacial advances
>>and retreats during the Permian Period.

There's also extensive Precambrian tillites in Australia that do
not correlate with the late Paleozoic nor the Cenozoic glacial deposits.

>You should also know that "tillites" are not only produced by glacial action.

It should not be hard to distinguish a true tillite from other ways
of generating grossly poor sorting (large rocks and mud mixed together),
based on the size of the deposit, source area of the clasts, shape of the
clasts, cold-associated fossils, presence of other glacial features,
glacial scratches on rocks, weathering of the clay minerals, etc. The
identification of many deposits as glacial rather than Noachian flood in
origin goes back to the mid-1800's, well before Darwin's publication.

David Campbell