Thread: Has there ever been the ice age?

This theory gained a footing only in the 1840s, when two researchers, Charpentier and Agassiz tried to explain the landscape forms of the Alps by using it and later it concerned the whole of Northern Europe. It is indeed surprising that this theory came to light almost at the same time as the thoughts of Darwin about the birth of animal species. Both these theories gained simultaneous attention in the society of the day.

In any case it has been thought that there have been several ice ages on the earth. It has even been said that such tropical and hot areas as The Sahara, Africa, Saudi Arabia, Yemen, Australia, India, Madagascar and also South America (as has been presented for instance in the books "Jääkausi� (Ice age) / Björn Kurten and "Muuttuva maa" / Pentti Eskola) would have been covered with a large continental glacier, tens of millions years ago. The latest ice age is assumed to have started "just" about 500,000 years ago and come to an end 10,000 years ago. Then ice sheets were supposed to have covered at their widest point 55 million km2 and the thickness of the ice would have been at its best over 3 kilometres (about 3,3 yards).

Why have we to think about the ice age? Have we any reason to believe in it? Perhaps those marks, which have been interpreted as those of an ice age, have been caused by something other than an ice age? We will now ponder the enigma of the ice age.

http://koti.phnet.fi/petripaavola/Ha...e_ice_age.html

Should you care to examine the southern and northern extremities of the planet you will observe that we are still in an ice age.

we are
since when is 3km the same as 3,3 yards, i am not so good on imperial units, basacly cause i hate them, but aint 1 yard about 0,9somethingmore meters?

the evidence of an ice age is simply to much to be ignored, thats the reason we "know" it have been.
the same with evolution
bigbang
earth creation
etc, when the evidence are to great to be ignored science "know" it have happened

Obviously this is *not* a religious question and one for Earth Sciences. Topic moved.

Ice is not motionless. Glaciers are not weightless. Ice builds glaciers and glaciers move. Glaciers on the move leave footprints. So when we find this footprints in places we don't see ice today, we know ice was there. From the extent of the damage, we know how much ice was needed to leave such a footprint.

exactly, or the fact that regions which used to be covered by ice (like Skandinavia) have risen enormously once the weight of the ice had disappeared. Easy to prove with marine sediments at mountain summits.

Originally Posted by Pendragon

. Easy to prove with marine sediments at mountain summits.

Ah, no. That was the Flood. :wink:

A flood elevating sea-level 3km, long enough for sediments to collect at mountain summits? Only god could do that :P

Isn't the idea to adress the subject question?

Yes the Ice Age was the last of perhaps 10 major glaciations each lasting on average about 50,000yr and separated by interglacial periods of 70,000yr. Toward the end of the Ice Age about 25,000yr ago, the ocean started freezing eventually causing ocean temperature to drop below that of the atmosphere/land. This caused the climate to change from cloudy to clear and the ice started to melt about 20,000yr ago. It is only because of the difficulty of adapting to these changes that forced and allowed man to evolve.

Any questions? I will try to answer.

Originally Posted by vgbell

Isn't the idea to adress the subject question?

The original poster clearly wants to see evidence of the Ice Age, so we discuss some landscape features which wouldnt be possible without one. In his opinion your description of the events is only a theory to be proven.

Speaking of which, I haven't seen PetriFB back here after his post..

It is not a theory. You can read it directly fron Antarctic ice core and ocean sediment data. I suppose the IA ending might be considered a theory but the evidence is in the sediment data if you can interpret it.

Originally Posted by vgbell

It is not a theory. You can read it directly fron Antarctic ice core and ocean sediment data. I suppose the IA ending might be considered a theory but the evidence is in the sediment data if you can interpret it.

Good, then we agree with eachother :wink:

Glaciers also explain how so called "erratics", or large bits of rock which are completely out-of-situ managed to end up where they are today. Before it was found that ice could flow, the placement of these erratics baffled geologists and many obscure and whack theories were hypothesized to explain their existance.

I suppose you could have glaciers without an ice-age, but what the heck, I thought I'd chuck that in because I'm sure you could (and someone's probably already done it) look at the occurence of erratics to prove the scale of the glaciation (generally, the nearer the equator the more extensive the glaciation), and thus deduce that there must have been an ice age.

There is no one single piece of evidence that says "there are ice ages". It's more a collection of evidence that shows us through scientific logic that this MUST have happened. Evidence from geology as others have discussed here, as well as biological evidence that we see from the fossil record of extinct species of Ice Age animals, as well as Anthropological evidence.

For example, we know that humans began to appear in the Northeastern United States around 13,000 years ago. This rather conveniently coincides with the timetable we know of for the receeding of the glaciers from this region. Before 13,000ya though, we know there were humans in North America. Therefore when this is added to the geological and biological proof, it fits perfectly. Humans could not live in the US NE becuase it was covered by glaciers. once those glaciers receeded, humans moved in. The archeological record supports this, and when pieced together, the geological and archaeological record fit flawlessly.

Geological evidence from my area of New York are unavoidable as well. When the glaciers covered the NE, they pulled up and destroyed much of the rock and soil that was there. This is why you do not find Dinosaurs in New York State. When the glaciers came through they destroyed and pushed up all rock newer than Devonian era (in Western new York at least). This is why in this region we have amazing oucroppings and exposures of fossiliferous Devonian, Odrvician, and Silurian bedrock.

Is there a main theory on the causes of the ice age? I heard somewhere that the sun's output fluctuates, that during the ice age, the amount of sun spots was decreased, lowering the amount of solar energy that hit the earth...and in turn, lowering the temperature. Is this true?

Another supporting piece of evidence is the 'petrified' tree remains and other 'land' artifacts found on the sea floor indicating those areas were above sea level at some time.

I think I read somewhere that the recent iceage began when North and South America joined at the Ismuth of Panama cutting off currents between the Atlantic and Pacific that moderated the Earths' climate. That occured several million years ago.

Originally Posted by MacGyver1968

Is there a main theory on the causes of the ice age? I heard somewhere that the sun's output fluctuates, that during the ice age, the amount of sun spots was decreased, lowering the amount of solar energy that hit the earth...and in turn, lowering the temperature. Is this true?

Solar Cycles are based on how many sunspots there are. Solar Cycles tend to be roughly 12 years long. Sunspots then would not have an impact on a multi-thousand-year process.

However the sun might still have a hand in the process being that it is the sole source of heat to the Earth. Maybe there is a longer term sun cycle (other than simple ageing) or perhaps some sun cycles are different to others (already proved likley). Other possible influences would include earth atmospheric changes, perhaps aggrivated by volcanism, impacts, variations in dust levels, carbon dioxide levels, and so on.


Edit: DarcgreY's idea certainly also has some merit.

Incidently it does show that earth's climate is a bit of a delicate thing... Bring on the Climate change debate