Ice Age, how many times has this event occoured?

Answer 1

An ice age is a period of long-term downturn in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers ("glaciation"). Glaciologically, ice age is often used to mean a period of ice sheets in the northern and southern hemispheres; by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist). More colloquially, when speaking of the last few million years, ice age is used to refer to colder periods with extensive ice sheets over the North American and Eurasian continents: in this sense, the last ice age ended about 10,000 years ago. This article will use the term ice age in the former, glaciological, sense; and use the term glacial periods for colder periods during ice ages and interglacial for the warmer periods.

Many glacial periods have occurred during the last few million years, initially at 40,000-year frequency but more recently at 100,000-year frequencies. These are the best studied. There have been four major ice ages in the further past.

There have been at least four major ice ages in the Earth's past.

The earliest hypothesized ice age is believed to have occurred around 2.7 to 2.3 billion (109) years ago during the early Proterozoic Age.

The earliest well-documented ice age, and probably the most severe of the last 1 billion years, occurred from 800 to 600 million years ago (the Cryogenian period) and it has been suggested that it produced a Snowball Earth in which permanent sea ice extended to or very near the equator. It has been suggested that the end of this ice age was responsible for the subsequent Cambrian Explosion, though this theory is recent and controversial.

A minor ice age occurred from 460 to 430 million years ago, during the Late Ordovician Period.

There were extensive polar ice caps at intervals from 350 to 260 million years ago, during the Carboniferous and early Permian Periods, associated with the Karoo Ice Age.


Sediment records showing the fluctuating sequences of glacials and interglacials during the last several million years.The present ice age began 40 million years ago with the growth of an ice sheet in Antarctica, but intensified during the Pleistocene (starting around 3 million years ago) with the spread of ice sheets in the Northern Hemisphere. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000 and 100,000 year time scales. The last glacial period ended about 10,000 years ago.

The timing of ice ages throughout geologic history is in part controlled by the position of the continental plates on the surface of the Earth. When landmasses are concentrated near the polar regions, there is an increased chance for snow and ice to accumulate. Small changes in solar energy can tip the balance between summers in which the winter snow mass completely melts and summers in which the winter snow persists until the following winter. Due to the positions of Greenland, Antarctica, and the northern portions of Europe, Asia, and North America in polar regions, the Earth today is considered prone to ice age glaciations.

Evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret. It took some time for the current theory to be worked out. Analyses of ice cores and ocean sediment cores unambiguously show the record of glacials and interglacials over the past few million years.

Answer 2

Many MANY times, and there is LOTS of scientific evidence of this. I will also caution you that I found several errors in the Wikipedia (6/06) page on this topic.

There is a hypothesis that the earliest ice age refered to as a 'Snowball Earth' was about 2.2 billion years ago. That is because glacial deposits have been found in rock of that age that was probably near the equator when it was deposited. Earlier periods of regional glaciation preceeded this as far back as 2.7 billion years ago. Here is an excellent explanation and a graph that shows the early Snowball Earth periods:
http://www.snowballearth.org/when.html...

Another Snowball Earth occurred about 710 Million years before present. Deposits from this period, called the 'Sturtian' have been found on every continent, suggesting that glaciation was common over most of Rodinia, as the continental land mass from that time is called. Here is a map of Rodinia:
http://www.scotese.com/precambr.htm...

To see a graph of global temperature change over the past 600 million years go here:
http://www.scotese.com/climate.htm...
You can see that during the late Ordovician (440 Mybp), the Early Permian (280 Mybp), and the more recent Pleistocene were all periods of cooler climate that had periodic ice ages.

The most recent ice age, the Wisconsinian glaciation, was between 10,000 and 70,000 years ago. Before that was the Illinioian betweeen 125,000 and 200,000 years, the Kansan (240-455 kybp), and the Nebraskan from 620-680 kybp. Other periods of glaciation in the Pleistocene preceeded those, and date back to the Pre-Pastonian from 800-1300 kybp. Here is some further information:
http://www.ngdc.noaa.gov/paleo/ctl/clisc...

More on snowball earth:
http://www.snowballearth.org/questions.h...

Answer 3

Many glacial periods have occurred during the last few million years, initially at 40,000-year frequency but more recently at 100,000-year frequencies. These are the best studied.

There have been at least four major ice ages in the Earth's past.

Answer 4

I saw the original but not Ice Age 2 yet.

Answer 5

NONE Not one
According to George Darwin , in his book TIDES , he proved mathematically that the earths oceans would have been lowered by 600+ feet. So what pushed the ice south? and how could the water evaporate to form snow if all icebound ? use your brain guys.
George was a math Prof at Cambridge
Why are the Rockeys so high and uneven ,while prairies so flat? ---same ice , different results-NOT logical ; in fact LAUGHABLE
For snow, sleet , freezing rain to EVAPORATE and fall I requires HEAT and how thick did you say the ice was?LOL

Answer 6

I do not think there is any scientific evidence that shows more than one Ice Age but if the global warming continues you might want to include a second in your prayers!

Answer 7

once. But this occurance lasted the majority of the lifespan of earth.

Answer 8

IT HAS HAPPENED ABOUT 4 TIMES THROUGHT HISTORY IF YOU LOOK IN WIKIPEDIA TYPE IN ICE AGE IT WILL TELL YOU EVERYTHING WIKIPEDIA IS AWESOME SORRY NOT YELLING JUST TO LAZY TO TAKE OFF CAPS

Answer 9

umm I'm not too sure it did, but if it did then only once cause the earth is under 10,000 years old

Answer 10

Just once. And hopefully not ever again. I hate being cold.