<p>It was a transition from a 41000 year cycle to a 100000 year cycle that happened about a million years ago (the <a href="https://en.wikipedia.org/wiki/Mid-Pleistocene_Transition" rel="nofollow noreferrer">Mid-Pleistocene Transition</a>), not from a 1000000 year cycle to a 100000 year cycle. There have been guesses (lots of guesses), but no one knows the definitive answer to this yet. One that I like is that the earlier glaciations eventually scraped the northern Earth down to bedrock, thereby changing climate responses to Milankovitch cycles. There are however many, many other possible explanations for this shift.</p>

CC BY-SA 4.0
2022-11-29T14:03:51.203Z
One of the nice things about questions where the correct response is "we don't know (yet)" is that this gives future generations of scientists problems to be solved. Once science does have the answer to everything, science will be kinda boring. Why would young adults aspire to be scientists in an age where science already has an answer to every question? Fortunately, there remain many unanswered questions / problems in the sciences. The mid-Pleistocene transition is one of the many problems left to be solved to future generations of scientists.
David Hammen
CC BY-SA 4.0
2023-07-22T20:38:36.413Z
But if we already knew, we could be spending our time on even more advanced things.  Why do things need to be boring, ever?
Michael
CC BY-SA 4.0
2022-11-28T21:40:07.407Z
2022-11-29T13:50:37.260Z
2022-11-29T13:50:37.260Z
David Hammen
<p>The Teglen (or Tiglian) interglacial period began after approximately half a million years into the Pleistocene, and the next interglacial (Waalian) occurred about a million years after that.</p>
<p>But the last half-dozen or so interglacial periods have been spaced about 100,000 years apart, rather than 1,000,000 years.</p>
<p>Is there a reason?  Or is there just not enough evidence of 'lesser' interglacials (or major interstadials?) during the early Pleistocene.</p>

<geophysics><ice-age><geologic-layers><milankovitch-cycles><age>
Why were the Interglacial periods in the early Pleistocene spaced about one million years apart, but recent ones only 100,000 years apart?
Kurt Hikes
# Why were the Interglacial periods in the early Pleistocene spaced about one million years apart, but recent ones only 100,000 years apart?

(Asked by: username_0 on 2022-11-28)

The Teglen (or Tiglian) interglacial period began after approximately half a million years into the Pleistocene, and the next interglacial (Waalian) occurred about a million years after that.

But the last half-dozen or so interglacial periods have been spaced about 100,000 years apart, rather than 1,000,000 years.

Is there a reason? Or is there just not enough evidence of 'lesser' interglacials (or major interstadials?) during the early Pleistocene.

**Tags:** geophysics, ice-age, geologic-layers, milankovitch-cycles, age


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## 1 answers

### Answer by username_1 on 2022-11-28. Score: 1

It was a transition from a 41000 year cycle to a 100000 year cycle that happened about a million years ago (the [Mid-Pleistocene Transition](https://en.wikipedia.org/wiki/Mid-Pleistocene_Transition)), not from a 1000000 year cycle to a 100000 year cycle. There have been guesses (lots of guesses), but no one knows the definitive answer to this yet. One that I like is that the earlier glaciations eventually scraped the northern Earth down to bedrock, thereby changing climate responses to Milankovitch cycles. There are however many, many other possible explanations for this shift.

> **Comments:**
> **username_1**: One of the nice things about questions where the correct response is "we don't know (yet)" is that this gives future generations of scientists problems to be solved. Once science does have the answer to everything, science will be kinda boring. Why would young adults aspire to be scientists in an age where science already has an answer to every question? Fortunately, there remain many unanswered questions / problems in the sciences. The mid-Pleistocene transition is one of the many problems left to be solved to future generations of scientists.  
> **username_2**: But if we already knew, we could be spending our time on even more advanced things.  Why do things need to be boring, ever?  

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