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DoubleDot7 t1_ixxid8i wrote

That's a great response. One thing to add: sea levels rise and fall over relatively short timescales, geologically speaking, which can greatly affect coastal map shape.

For example, 40,000 years ago, during the last ice age, sea levels were lower. Thus, there was solid land between Siberia and Alaska (Beringia land mass), and the British Isles and the Netherlands. Our current coastal regions were inland regions, and what is now submerged land was once the coast. In some areas, such as southern Africa, this could mean that the coast was several hundred kilometers further out than it is today. Islands such as New Zealand would have been bigger and possibly connected, too.

On the other hand, if sea levels keep rising, we may have to remove parts of Florida, New York, California and many island nations from maps over the coming decades and centuries.


CrustalTrudger t1_ixyxy4z wrote

Yes, though broadly changes in eustatic sea level are one of the things that we attempt to account for when making paleogeographic maps and as mentioned in the original answer, depositional environments can provide some context to the location of coastlines, etc. That being said, the point is valid in that paleogeographic maps tend to be amalgamations of time periods, i.e., at the finest scale we might make a paleogeographic map that represents the "average" of a few tens of thousands to few million of years of time and certainly within that you would expect a decent amount of sea level variation. All and all, a paleogeographic map would give you a rough approximation of things and would be better than nothing, but yeah, you would need to expect it to be pretty wrong at times.


Due_Avocado_788 t1_ixxoa33 wrote

The article you linked says this bridge is theorized to be in effect just a few thousand years ago. That's super interesting