0
$\begingroup$

The established fact is that the shape of a planet's continental coastlines is determined by the planet's climate. Higher temperatures mean less ice, which ultimately means higher sea levels. (Case in point, the early Cretaceous.) Lower temperatures have more ice, which sucks up water like a sponge, leading to a drop in sea levels, like what'd happened during the Pleistocene's glacial maximums.

enter image description here

This is a map of Earth right now. Currently, it stands at an axial tilt of 23.5 degrees, and the mean surface temperature is 14 degrees Celsius.

enter image description here

And this is a map of an alternate Earth. Never mind the different colors--they don't have anything to do with the question. It's still the same size as Earth, and orbits the sun from 93 million miles, just like ours. Axial tilt is still 23.5 degrees. However, the different arrangements of the landmasses result in a mean surface temperature of 12 degrees Fahrenheit. Yet, as we can see, in spite of the cooler temperature and disregarding some differences, the global coastline remains mostly identical. What sorts of geological or astronomical factors could make this possible?

$\endgroup$
  • 1
    $\begingroup$ Any chance that you could provide a Map Key to the different colours and shades, at the moment there's a huge oil slick over Russia etc., I'm sure that that's not what's intended. The browns, I assume don't represent degree of desertification - or do they? The white is what? Ice desert? If there were that much ice desert then why isnt the north atlantic frozen - or maybe it is - can you tell us? Are you asking about continental drift differences - is that your question, because it's not clear. $\endgroup$ – We are Monica. Feb 17 at 1:51
  • $\begingroup$ @Agrajag Reread the second sentence of the last paragraph. $\endgroup$ – JohnWDailey Feb 17 at 1:56
  • $\begingroup$ So you're saying that the question has to do with the effects of climate on continental drift? There is no scale on either of the maps, what do the differences signify? How is this anything other thatn cartographical error? $\endgroup$ – We are Monica. Feb 17 at 1:59
  • 1
    $\begingroup$ Google image found that map to be your own creation. Very interesting. You might link the source or take credit for it or both. $\endgroup$ – Willk Feb 17 at 3:41
  • 1
    $\begingroup$ Add more water. $\endgroup$ – Vincent Feb 17 at 4:35
4
$\begingroup$

What sorts of geological or astronomical factors could make this possible?

None. At least that are plausible.

I annotated your map for you:

enter image description here

You now have water on areas that are essentially mountains.

  1. Baja California has many areas higher than 500 metres, with mountains reaching higher than 1000 metres. It is now all underwater.
  2. Sierra Nevada and Colorado Plateau are mostly higher than 1000 metres. Now all underwater.
  3. The Tibesti mountains in central Sahara are likewise mostly higher than 500 metres.
  4. The Zagros mountain range has mountains higher than 4000 metres! Now somehow it's underwater.
  5. The Congo basin is higher than 500 metres.
  6. The Karoo (actually your lake is a bit north of that) is also higher than 500 metres.
  7. The only one that can somehow make sense is the lake Eyre region in Australia, where you connect it to the ocean. It's a very low area, sometimes even below sea level.

Astronomical factors

No. If you want sea level to rise, you can't flood the mountain ranges without flooding the coast lines. Even then, with 0 glaciers on Earth, you will not have enough water to cover the mountains. Raining on the mountain ranges is also not reasonable because it will all just flow to the ocean.

Geological factors

Not really. Unless you want to redefine geology as we know it. Yes, you can make up a reason why these places are oceans and not continental mountain belts (for example - Zagros is still a Tethyian subduction zone), but then you can just make up everything and you don't need us to give you an answer. This makes no sense.

$\endgroup$
  • 1
    $\begingroup$ I like your annotations! $\endgroup$ – Willk Feb 17 at 12:17
1
$\begingroup$

A small correction to your statement points to the answer: the shape of the coast line is determined by the sea level AND its interaction with the height profile of the landmasses. I.e. in case of sea level reduction a slow declining sea bed will extend the coast line more than a rapidly falling cliff.

Thus, the different arrangements of the landmasses will likely result also in a different arrangement of their height profile and, for the particular sea level in your map, lead to a mostly identical coastline.

$\endgroup$
0
$\begingroup$

I see a lot of bodies of inland water, not related to the coast line. The Middle East, for example, or the New York area, or central Australia. If the depressions in these areas are deep enough (and recall that water is heavy, so a water mass of that quantity would depress the earth even further) it is possible that the entire water mass liberated from glacial and snow melting from land masses (remember, when ice at sea melts, there is no rise in water level - the volume of water just replaces the volume of ice) is entirely made up by the water in these huge inland bodies of water.

$\endgroup$
  • $\begingroup$ Can you expand or clarify on that? It looks as though you're on track, but I'm having a bit of a difficulty understanding. $\endgroup$ – JohnWDailey Feb 17 at 3:44
0
$\begingroup$

They must be artificial.

There is no geological or astronomical difference which would explain those inland bodies of water with an intact coast. In fact I recognize of these water bodies from grand schemes to build inland lakes.

The Congo Basin Lake was put forth by Willy Ley in his book Engineers Dreams.
http://johnhawks.net/weblog/reviews/books/ley-engineers-dreams-2009.html

The Halfbakery has schemes for the Australian Sea https://www.halfbakery.com/idea/The_20Australian_20sea#1480511846

and also Lake Death Valley. https://www.halfbakery.com/idea/Lake_20Death_20Valley#1033923600

These two are salt seas, not lakes as they are set out in the Halfbakery.

Dam Hudson Bay I think would have made a single water body contiguous with the Great Lakes but here Hudson Bay looks intact and the Great Lakes have been made contiguous. But maybe this is one step in the process? Maybe it has not filled in yet?

Usually there is something for the Caspian Sea included in these schemes but maybe that it hidden on this map.

$\endgroup$
  • $\begingroup$ They are all natural. $\endgroup$ – JohnWDailey Feb 17 at 3:51
-1
$\begingroup$

Just invent a new world, that'd be much easier than explaining, how and why certain differences to our Earth were shaped.

In addition to @Willk and @Gimelist answers you ditched all of Indonesia, thus basically nullifying the Pacific Ring of Fire, you erradicated the Arabic Peninsula, which is its own sub-plate, and you moved Greenland even farther to the north, which is even weirder, since - as far as I know - it even isn't a separate plate. To sum it up: Your whole geology/plate tectonic differs very much from our Earth's. Therefore, you'd have a hard time explaning why the rest of your earth looks to much like ours. Sure, you could handwave it away, but I would at least slightly scowl at your story.

The only plausible thing you did, as far as I can see, was drowning the Netherlands.

$\endgroup$
  • $\begingroup$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review $\endgroup$ – Alex2006 Feb 18 at 13:32
  • $\begingroup$ It does answer the question "how is the depicted change possible" @Alex2006. It really isn't. Because in some areas the sea level is 500 m or way more higher than currently, and in others it is 50 to 100 m lower. Break the laws of physics, then it might be possible. $\endgroup$ – Erik Feb 18 at 14:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.