21–30 of 75 posts
I wonder if there are continents we'll never know about because they get completely subducted and aren't part of any existing continent today.
Very cool. Like many of these tools it suffers from northern hemisphere bias that hides interesting information about the southern hemisphere. In looking to correctly simulate axial tilt we get Gondwana and Antarctica hidden from view in the shadow, their sunlit versions only available via options rather than hidden by default. The southern polar region is the more interesting of the two for the vast majority of geol…
- the tilt of the earth was substantially different. Where Florida is today, would have been where New York was then. [1]
- the poles (north & south) were in radically different places than today. There’s evidence that dinosuars flourished in what is the artic today because the artic then wasn’t so cold [2]
https://theswaddle.com/earth-had-a-dangerous-axis-tilt-84-mi....
https://www.snexplores.org/article/dinosaur-arctic-bone-foss...
It's comforting to know there wasn't any ice at the north pole 20Mi years ago, and humans survived just fine.
Earliest humans, Homo Habilis, appeared 2.4-1.4 Mi years ago.
This is awesome. I like how it goes from 20 million years ago to present in one jump, which is sort of interesting on the timeline. We had a warm period without ice ages 3-5 million years ago, then had the onset of ice ages 2 million years ago(and that cycle might have been terminated by current fossil fuel use). Just a blip in time from this perspective.
Just so we’re clear—the most recent ice age was already ending before the industrial revolution. Unless you believe like a couple did in the 70s that there was a coming ice age which we completely stopped and reversed. I would love to hear the steelmanning for that.
Some time ago I had this thought: The original (single) continent was round, and about the diameter of the moon. Since the moon was much closer to the earth, it's gravitational pull would give rise to a bulge (an earth "tide" if you will), which would be roundish and about the size of the moon's visible diameter. I am definitely not a geologist, and this is probably un-provable... but, to me, it sure seemed like a pl…
Your idea's first hurdle is the length of day vs the length of month. How do you keep the moon over one bulged part of Earth at all times? (it's a very different story for the moon, whose 'day' is as long as its orbit, more at [1]) Additionally, there is a solar tide at work on the oceans that is visible daily, and especially at spring and neap tides. The sun's mass drives a maximum of almost a third of the total ocean tidal bulge.
The second hurdle is viscosity (or if you like, elasticity): tides bulge the most readily-flowing parts of a body the strongest. That means the atmosphere (which is more strongly affected by daily heating https://en.wikipedia.org/wiki/Atmospheric_tide>), and the oceans are much more strongly affected than the "asthenosphere" (the rocky parts).
In particular, tides bulge the ocean by about a metre. The solid earth tide is closer to 0.2 metres. Thus, the question is: how do you raise a tidal bulge in the rocky part of Earth and keep it from being flooded by ocean tides?
> I am definitely not a geologist
It's more gravitation vs the liquid flow of a stratified (layered) planet than geology that is are the big hurdles.
For experts, tidal Love numbers are the important things for any round stratified body: https://en.wikipedia.org/wiki/Love_number>, which describe the bumpiness (mass multipole) raised by tidal fores on a spherical body immersed in a tidal gravitational field.
The mantle's rheology (elasticity, viscosity, rigidity), representing about 85% of Earth's total volume, is the primary driver of the Earth's Love numbers. There's more detail on that here: https://geodesyworld.github.io/SOFTS/solid.htm#link3>.
The crust is quite low-volume by comparison. So a third hurdle is straightforwardly: if there were a persistent bulge in the mantle, why wouldn't a relatively thick part of the crust (a giant continent in your idea) not just "roll downhill", or conversely, how do you get fractions of a round supercontinent to "roll uphill" to some lunar-attraction-induced meeting point?
Finally, with present understanding of continental drift, the continents tend split apart and come together over millions of years, and there's no evidence for anything approaching circularity. The link at the top lets one step through almost a billion years of continental drift, showing this fairly clearly.
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[1] Slide 8 ("Tides (2)") of the lecture notes at https://websites.pmc.ucsc.edu/~fnimmo/eart162_10/Week8.pdf> is pretty accessible, showing an Earth-centric diagram of tides and a moon-centric diagram of its tides, and throughout the rest of the slide deck there's lots of heavy stuff for people who like to grapple with mathematics.
Keep in mind that: - the tilt of the earth was substantially different. Where Florida is today, would have been where New York was then. [1] - the poles (north & south) were in radically different places than today. There’s evidence that dinosuars flourished in what is the artic today because the artic then wasn’t so cold [2] https://theswaddle.com/earth-had-a-dangerous-axis-tilt-84-mi... . https://www.snexplores.org…
What a completely scitifically illiterate article.
It's showing Tasmania separated from the Australian mainland 20,000,000 years ago, even though supposedly it separated only 12,000 years ago? Also, the constant spinning is super infuriating and mildly sickening.