The 1958 encyclopedia says the "dome" in question is 13,000 ft high and located at about 80^o S, 90^o E.

That's probably dome B, an ice dome.

Dome B is 3809m (=12,500 ft) high and located at 79^o S, 93.6^o E.

What is an ice dome then? 13,000 feet at the point of contact of the firmament with the mountain reflects what we know about flat earth.  How does that jive with the ball earth?   

What leads you to think the "dome" mentioned there is a sky "dome" over a flat earth? And that this would be stated in a 1958 encyclopedia?

No, that "dome" is an ice dome, a hill in a glacier.

Here's a map showing Domes A, C and F.  There are many more ice domes in Antarctica.
https://www.researchgate.net/figure/A-Map-of-Antarctica-with-locations-of-Dome-A-Dome-C-Dome-F-and-Vostok-B-surface_fig3_263441612

The graphics provided do not show a dome structure.  Sorry, not buying.  

As others have said, the key is Antarctica.  Why do world leaders secretly visit there?  What's to see?  Why are there multi military bases there?  What is being explored?  What is being kept secret?

A few things i've run across that *might* be true (I have no way to prove):
1.  The Book of Enoch (was considered part of Old Testament in Christ's day but post Jerusalem destruction in 70AD, it's texts were lost, so it was left out of canon).

  a.  Enoch describes a place geographically similar to Antarctica where the "fallen angels" of Noah's days were chained in the center of the earth.  These are not devils but the "evil spirits" who roam the earth, when God allows.
  b.  The point is, I believe that part of Christ's allowance for the devil's "100 years of power" in Pope Leo's vision was to allow these "fallen angels" to communicate with men directly, so to advise them on how to build satan's kingdom (if God so allows it).
  c.  Such communication happened in the day's of Noah, which led to the Nephalim, and also post-Flood, when the "Giants" roamed the earth and which led to the construction of the Tower of Babel (one of the first attempts at building satan's kingdom on earth).

2. Antarctica is very mysterious and off-limits.  Why?
  a.  Antarctica is supposedly very mineral-rich and might not be as cold as we are led to believe.  Some scientists say that there are tropical like conditions in the lower regions of the ice, with warm waters, which is one reason why the "polar ice caps" melt on a normal, routine basis.
  b.  There are military bases in Antarctica (that we know of) - what else was built there that we don't know about?  Imagine what could've been built there in the last 70 years, with a combination of money, effort and planning between every major nation on earth?  The possibilities are staggering. 
  c.  I think this is where the elites keep all the super-high-technology that they've been working on.  I think "Area 51" was invented (with the alien story) to make people focus on this area, while forgetting all the vast regions of Antarctica, and why the elite global leaders travel there multiple times a year (probably to communicate with devils).
  d.  Antarctica being off-limits also hides the flat earth, which if people found out, would make the entire scientific house-of-cards-community of the past 150 years (going back to evolution) to implode.  People would immediately realize that almost everything they've ever been taught is a lie and society would return to truths which were commonly accepted back in the 1700s, before technology replaced common sense.

I don't believe in flat earth, but I also find Antarctica to be a fascinating place. Here are some ideas that I have about what could be there: 

1) This is a bit fantastical, I know, but hear me out. Going off the "tropics under the ice" idea, perhaps there could be some creatures living down there that the elites don't want people to have access to, mainly thinking here supposedly long extinct animals like dinosaurs. If there is some method of lighting down there, which perhaps some kind of crystals or plant may provide, it would create the conditions necessary (alongside the water and heat) for lush jungles to exist, which would be an environment suitable for the continued existence of those creatures. 

2) Ruins of antediluvian civilizations under the ice or on the surface of Antarctica. I imagine that since the antediluvian civilizations were possibly far more advanced than our own in terms of technology, these ruins would portray a style of architecture so advanced it would seem...alien. TPTB don't want people to think that there were civilizations more advanced than our own in the past, because that would ruin their idea of human "progress" ascending constantly upwards throughout history, which they take from Darwinism. It would also make the masses question the "official history" they were told in a major way if this information was leaked to the public. I think they have a contingency plan, maybe even a slight of hand in place for this if these ruins actually exist. They will market them to the public as being the remains of an advanced "alien" civilization, and hide all evidence that would indicate humans actually built them. 

It would prove evolution to be false if there were prehistoric creatures around. I beleive there are some in the amazon jungles somewhere.

Amazon jungle.



I mean, dude, there has to be dinos here somewhere.

Amazon jungle.



I mean, dude, there has to be dinos here somewhere.

Good one! 

There's definitely plastic dinosaurs in there, for sure! 

Well, dinos per se were too big to fit on the ark, and were likely all wiped out in the flood.  But Noah took some smaller types of related animals on the ark.  Recall that Noah was commanded to take two of each TYPE (or genus) onto the ark.  He didn't necessarily take a couple of every species.

There were many dinosaurs that were actually quite small. It's possible that Noah took in juveniles of some of the larger species. That leads me to another point: due to the fact that we have no living dinosaurs to observe, it makes it difficult to define how closely related one species was to another, or if two specimens that were actually members of an existing species were classified as being different species by paleontologists. There's even obscurity among biologists about what a "species" really is, but apparently the most sensible explanation is that if two creatures can successfully reproduce healthy offspring, then they are a part of the same species. (I'm not sure then what to infer about the relationship between tigers and lions, since they can reproduce under certain conditions to bring forth what are known as ligers). 

There's many debates among paleontologists about this sort of thing, because the only info we publicly have are bones and fossils, that's it. It's why Brontosaurus was no longer considered a dinosaur for years, as it was said that remains attributed to that animal actually were the same as those classified as belonging to Apatosaurus. Recently, Brontosaurus has been again classified as a different species. 

Plus, we don't really have any clues as to how long these animals lifespans were, and how fast they grew to their maximum height. It's possible that it would take many decades for some of the huge dinosaurs like Brachiosaurus to reach their maximum heights, but we just don't know for certain. 

Why are chemtrails level for miles and miles?  Shouldn't they look like rainbows over a curved earth?

It takes 70 miles for the earth to curve 1^o, and you're looking at contrails from the side.

Could you see a 1^o bend in a broom handle or rod from the side?

Looks like a curved track leading round the equator on a flat earth. 

No matter how subtle, sheer distances proves accounting for curvature must be done.  A mere 50 miles of track must curve downward about 1/2 mile.  That's approximately 2500 ft. Each piece of track would have to compensate a fraction of that total, yet it would be necessary to ensure each piece of track is bent in order to maintain curvature of what is said to be the globe.  Conversely, unbent track, the way it's manufactured now, can never wrap around a curve or follow the contours of a ball shaped earth.