A famous map of southern hemisphere and Antarctica in particular.
In recent years, people have been digging forth old, beautiful maps and read them with great care - now that there's no nasty dragons just outside the borders. (Actually, they're still there. Most people just don't look closely enough.)
So, one day Graham Hancock found a map made by Philippe Buache in 1739. He was somewhat shocked by what he saw, and told about it in his book Fingerprints of the Gods. Since then, this observation has gained an extremely memetic following - the book sold pretty well.
What he saw on the paper was indeed an interesting sight. Earliest good maps of Antarctica date back to early 1800s. Here he saw what he thought was Antarctica without a layer of ice on top of it. In fact, it looked a lot like what the recent geological surveys have shown the subglacial Antarctic continent to be: two big land masses, with a channel going through it, and a larger sea in the middle.
Now, Buache (who has since been remembered as "a great academian, if we don't count the damn map"), was a cartographer, not really an explorer. It was a known practice to combine maps from other sources. In the books, it is often said that these maps go all the way back to Greece or Alexandria in Egypt or places like that - Egyptians, with their cool mathematical wonders, obviously mapped the whole Earth, particularly the un-iced Antarctica of 4000 BC! "But wait", thought I, "Isn't Antarctic polar cap sort of older than that?" Not to worry, said he, maybe it was made by the folks of Atlantis, who lived there before the Ice came - that's what everyone in Young Earth Creationist circles claim! And at that point, I thought this thing had to be investigated. =) It's all nice and jolly to hypothesise with ancient maps; To use them for ends of pseudoscience is an offense...
Actually, even when I don't know much of the large-scale geography, my gut feeling was right after I checked (I'm not that gullible, you know =)... The ice formed millions of years ago, it was not suddently "gone" 4000 BC when the Egyptians (or anyone else with pen and paper) were around to make notes. Also, it might be worth noting that scientists today are able to say "well, there may be sort of like two land masses and sea in the middle, you know, but we really can't know for sure because our sensors aren't that accurate, and besides, there's helluvalot of ice there pushing the continent down too, so we have no idea what the Antarctica would look like if that ice would suddently disappear like a bad smell to Sahara and the continent would pop back up, sort of like it's still doing after last ice age in the banks of Bothnian sea where the writer lives".
It is true that Buache's map is one heck of a combined job. The job proceeded easily: Someone asked for a map of Southern Hemisphere, so a fleet left to explore, came back with sailors' ideas of maps, and combined them to a map.
Most people who look at the map ignore the fact that there's writing on it. It's in French, naturally, and uses jargon and idioms from 1700s that no one understands, but is still understandable in main points to anyone skilled in the language. The text details the voyages of the ships, also talks of icebergs, glaciers and other stuff like that that sounds pretty outrageous, considering the claims that this was supposed to be an iceless map. Also, on parts, they comment that some ideas on the map are fiction. (Map makers were obviously getting more honest!)
Closer look gives away even more interesting details. There's something called "Nouvelle Zelande" that's part of the Antarctic land mass, and even some place called "Terre de Deimen". Some people claim that these maps are a proof that the Antarctic and Arctic regions would have moved during the recent history, but at least these maps place New Zealand and Tasmania just where they are today.
The commentary in the map doesn't even claim the map would be anything extraordinary. In fact, it just says it's based on the "memories and the original map of Mr. Bouvet, who was in charge of the expedition."
The fact that there's an "inner sea" doesn't magically claim mean that they consulted "ancient maps" that had preglacial Antarctica. It was just thought in 1700s that icebergs form on such sea, so it ended up to the map. In fact, the map clearly labels it as a "conjecture". (My memory is a bit hazy, but didn't Jules Verne mention something similar in that submarine book thing?)
What do we learn from this? Take old maps with large grains of salt, and don't draw wild conclusions based on "recent research"...
The map is currently in Library of Congress in Washington DC.
"Here There Be Pænguins. Aww heck, who reads these notes anyway?"
(Big Honkin' URL alert:)
Excellent page with big scans, long stories, and translations of the texts.
A Corruption of European History - Buache's Map of 1739. Author:
Myth-slaying by Paul V. Heinrich.
See also: Piri Reis map - shows the Antarctica, and some people claim it's also "without ice"...