[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Australian Dropstones & misc.refs



"Tracy L. Ford" wrote:
> 
> Ok, explain to me how this works? For an iceberg to move in the ocean it has
> to be from a deep or deeper shallow water to move. How much do you see above
> the water? Is it 10% or more? Then the sea water has to cover the 'mud' area
> right, or else how else can the iceberg move over the mud? Did if flow up
> river? Is the mud from freshwater or salt?

Since I haven't looked at the paper myself (or the 1995 updated
version), I can't really comment. That said...

The term "iceberg" may not refer to the massive "90% under water"
variety. If glaciers were reaching the ocean and calving, I imagine
dropstones could have been carried for at least some distance by
relatively small bergs (say, the size of a car or less). For all we know
they may have been well on the way to melting by the time they reached
sea level.

As for the mud: since the inland sea was fairly shallow, and rivers
probably drained into it from most sides, perhaps there was a lot of
river-bourne sediment entering the sea (perhaps contributing to its
shallowness?). Or perhaps some of the mud was contributed by slushy,
melting glacial ice calving off into the shallow reaches of the sea. All
speculation on my part of course.

On a related topic, I've found that the figures in the PDF version of
Gurnis et al 1998 "Cretaceous Vertical Motion of Australia and the
Australian-Antarctic Discordance" Science 279:1499-1504 seem to be
encoded into the document using some sort of vector image format, since
magnifying the images doesn't seem to cause much pixelation. Here's a
link to some of the pics I captured from it:

http://www.alphalink.com.au/~dannj/temp/oz-083-070.gif
http://www.alphalink.com.au/~dannj/temp/oz-099-091.gif
http://www.alphalink.com.au/~dannj/temp/oz-104-099.gif
http://www.alphalink.com.au/~dannj/temp/oz-110-104.gif (Approx. Dinosaur
Cove time)
http://www.alphalink.com.au/~dannj/temp/oz-119-114.gif (Approx. Flat
Rocks / Koonwarra time)


-- 
________________________________________________________________

Dann Pigdon                   Australian Dinosaurs:
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
________________________________________________________________