Are we heading for an Ice Age

[Baron von Richthofen (Vaclav)]

Are we heading for an Ice Age, earth gets one about every 40,000 years and we are over due and we are supposed to be in global cooling mode
When there is an Ice Age the northern hemisphere freezes and the southern hemisphere gets hot and dry

[Kal (Andrew)]

I don't think the southern hemisphere gets hot and dry. During the last ice age the Australian mainland had glaciation at Kosciusko, and both tasmania and New Zealand had glaciation.

[erick (Eric)]

Not in the immediate (some centuries) future.

[AstroJunk (Jonathan)]

If we are, I bet the government will find a way of taxing us for it as if it were our fault.

There will be glacial duty on icecream ...

[AstralTraveller (David)]

Originally Posted by Kal

I don't think the southern hemisphere gets hot and dry. During the last ice age the Australian mainland had glaciation at Kosciusko, and both tasmania and New Zealand had glaciation.

Yep, cold and dry with many more dust storms. Sand dunes developed in places like northern Tasmania and the Blue Mountains. Yet the inland rivers carried a larger load and, at times, there was lots of water around Lake Eyre and the northern Flinders Ranges. All very confusing but don't worry, people are merrily spending your taxes to work it all out.

[Enchilada]

Originally Posted by Kal

I don't think the southern hemisphere gets hot and dry. During the last ice age the Australian mainland had glaciation at Kosciusko, and both tasmania and New Zealand had glaciation.

Actually, there is a general dispute over the amount Pliocene glaciation of Mt. Kosciusko, whose claims go back to Galloway, RW, "Glaciation in the Snowy Mountains: A Re-appraisal" (1963) - I think damage of the landscape from hot and cold (frost can slowly break up rocks ) was more of the cause of the appearance than glaciation. Also several million years ago, Australia, New Zealand and Tasmania was all much further south, so that it is thought that most of the evidence of glaciation would have occurred much earlier than the last Ice Age. (it also explains the geological differences from the Ice Ages between Australia and South America, as South America was closer to the equator - moving presently southwards.
The Snowy mountains is also an interesting point, as in the past, the volcanism of the whole Great Dividing Range some 20-25 million years ago. Many of the geological features, I think, were created by variances in the terrain by erosion and not necessarily glaciation. I.e. Most of the valleys haven't got the familiar "V" shape of glaciers but are in fact more flatter "U" shaped.
However, it is a good point you are making here.

[Omaroo (Chris Malikoff)]

Originally Posted by Enchilada

Many of the geological features, I think, were created by variances in the terrain by erosion and not necessarily glaciation. I.e. Most of the valleys haven't got the familiar "V" shape of glaciers but are in fact more flatter "U" shaped.

V-shaped, glacier-hewn features normally end in huge moraine fields, making it easy to discern what type of erosion has occurred.

Moraines on Schnells Ridge, southwest Tasmania, have been dated using in situ 10Be. An age of 19,400 ± 600 yr is indicated for the well-preserved innermost moraine from consistent measurements on four large quartzite boulders. This corresponds closely with exposure ages reported by T.T. Barrows et al. (2002, Quaternary Science Reviews 21, 159–173) for Last Glacial Maximum glacial features farther north in Tasmania and southeast Australia. In contrast, ages between 39,000 and 141,000 yr were obtained from a series of boulders on a more extensive outer moraine, indicating that this has had a more complex history.

Author Keywords: Glaciation; Tasmania; Cosmogenic nuclide dating

http://www.sciencedirect.com/science...d155c5efea9b97

[Enchilada]

Originally Posted by Omaroo

V-shaped, glacier-hewn features normally end in huge moraine fields, making it easy to discern what type of erosion has occurred.

I don't think I disagree with you at all. I was thinking more of the region surrounding the Snowy Mountains. My point is the geology of this region just isn't as clear-cut - just as your reference says.

[Omaroo (Chris Malikoff)]

Originally Posted by Enchilada

...the geology of this region just isn't as clear-cut.

..as such.

Very droll... LOL!

[Enchilada]

Originally Posted by Omaroo

..as such.

Very droll... LOL!

Sorry. Not intended.

[Enchilada]

Baron

You might like to read the following interesting links regarding this…

Paleoclimatology : Explaining the Evidence
http://earthobservatory.nasa.gov/Fea...logy_Evidence/

Southern hemisphere glacial and estimated sea ice coverage (see map)
http://www.ncdc.noaa.gov/paleo/slide...178_slide.html

Note ice formations in South America and not Australia

… and the Northern Hemisphere;
http://www.ncdc.noaa.gov/paleo/slide...177_slide.html

You might also like to look at some of the graphs;

Glacial and interglacial Scale
http://www.ncdc.noaa.gov/paleo/ctl/clisci100k.html

(especially a. and b. at the bottom of this page)

[ngcles]

Hi All,

Originally Posted by Enchilada

The Snowy mountains is also an interesting point, as in the past, the volcanism of the whole Great Dividing Range some 20-25 million years ago. Many of the geological features, I think, were created by variances in the terrain by erosion and not necessarily glaciation. I.e. Most of the valleys haven't got the familiar "V" shape of glaciers but are in fact more flatter "U" shaped.
However, it is a good point you are making here.

I'm no geologist by any means but I thought alpine glaciers produced "U" shaped valleys out of "V" shaped ones? Thats not to say the valleys in the Dividing Range are Glacial (they're not) -- but I thought a glacier converted the valley they were in from "V" to "U" via erosion?

Obviously we're talking about alpine glaciers here -- not the ice sheet variety (like Greenland) that cover a continent.


Best,

Les D

[renormalised (Carl)]

Originally Posted by ngcles

Hi All,



I'm no geologist by any means but I thought alpine glaciers produced "U" shaped valleys out of "V" shaped ones? Thats not to say the valleys in the Dividing Range are Glacial (they're not) -- but I thought a glacier converted the valley they were in from "V" to "U" via erosion?

Obviously we're talking about alpine glaciers here -- not the ice sheet variety (like Greenland) that cover a continent.


Best,

Les D

You're correct, Les. Glacial valleys have a characteristic "U" shape and not a "V" shape.

[Omaroo (Chris Malikoff)]

Wood for the trees! Yep - U-, not V. My bad for quickly answering without thinking!

[renormalised (Carl)]

Originally Posted by Omaroo

Wood for the trees! Yep - U-, not V. My bad for quickly answering without thinking!

Don't you mean scree for the eskers....too cold for trees

[JimmyH155]

40,000 years???? I thought it was more like 12,000 years ago the last one, and on average one occurs ev 10,000 years so we are 2,000 years overdue
I hope so because I want to sell up here in Brissie - should get lots of refugees from the southern states, and I can double my asking price

[Rod66 (Rod)]

I saw some media articles from Kevin Rudd. He assures us global warming is on its way. Surely you don't doubt him?

[Enchilada]

Originally Posted by ngcles

I'm no geologist by any means but I thought alpine glaciers produced "U" shaped valleys out of "V" shaped ones? Thats not to say the valleys in the Dividing Range are Glacial (they're not) -- but I thought a glacier converted the valley they were in from "V" to "U" via erosion?
Les D

What was I thinking! (Better to stay with the astronomy, methinks.)

I said; "Many of the geological features, I think, were created by variances in the terrain by erosion and not necessarily glaciation. I.e. Most of the valleys haven't got the familiar "V" shape of glaciers but are in fact more flatter "U" shaped. "

Of course this is the case. I just getting my u's and v's mixed up. * The truth is that the variances in the terrain are due to various geological processes, including erosion and volcanism.

I should have said;

"Most of the valleys (in the Snowy Mountains) have got the familiar "V" shape, where glaciers but are in fact more flatter "U" shaped."

It is very interesting that the geologists list only three glacial regions here. There nature seem interesting, as the mountains are not overly high, so the glacier don't flow down hill but are so-called stationary glaciers. Movement from entrainment - material from the bottom surface or the valley sides. (Note: The wiki article on Glaciers seems reasonably informative on the subject (for a change.))

* It is like the general confusion with the Greek letters of ν nu and υ upsilon. In shape of the letter mean v comes before u , which is opposite the normal alphabet! nu and upsilon for star names is always confusing.

[ving (David)]

in short yes...

... in long yes we are, or at least i believe so.

[renormalised (Carl)]

Originally Posted by Enchilada

What was I thinking! (Better to stay with the astronomy, methinks.)

I said; "Many of the geological features, I think, were created by variances in the terrain by erosion and not necessarily glaciation. I.e. Most of the valleys haven't got the familiar "V" shape of glaciers but are in fact more flatter "U" shaped. "

Of course this is the case. I just getting my u's and v's mixed up. * The truth is that the variances in the terrain are due to various geological processes, including erosion and volcanism.

I should have said;

"Most of the valleys (in the Snowy Mountains) have got the familiar "V" shape, where glaciers but are in fact more flatter "U" shaped."

It is very interesting that the geologists list only three glacial regions here. There nature seem interesting, as the mountains are not overly high, so the glacier don't flow down hill but are so-called stationary glaciers. Movement from entrainment - material from the bottom surface or the valley sides. (Note: The wiki article on Glaciers seems reasonably informative on the subject (for a change.))

* It is like the general confusion with the Greek letters of ν nu and υ upsilon. In shape of the letter mean v comes before u , which is opposite the normal alphabet! nu and upsilon for star names is always confusing.

Yes...better leave this to us Geologists ( who are also astronomers )