The Persian Gulf has been a hotspot of contention ever since some Sumerians decided they wanted to live next to each other a few thousand years ago. Recently, Arab dominated lands have referred to the body of water as the Arabian Gulf, which has led to a vehement outcry among Iranians (or Persians, for anyone alive before 1935). This nationalism has evolved to the extent that Iran now has a Persian Gulf Day (on April 29th, in case you planned on taking the day off). You might also notice the rather undiplomatic language that seems to permeate Iranian literature on the subject. To their credit, the UN and some random guy at MIT (someone in Iranian Studies, anyway) have determined that Persian Gulf (or variations thereof) has functioned as the de facto name for the gulf in European circles for centuries and should stay that way. I'm not really sure where the Arabian prompt to change the name is coming from - they have a perfectly fine Red Sea to the west that could do with a spruced up name. Maybe they're hoping the next war in the area to be a more eponymous Arabian Gulf War instead of a Persian Gulf War.Now, my History 104 course with Professor Wick also featured a bit of discussion on the popular gulf (he also writes a mean introduction to the History of the Peloponnesian War by Thucydides). One of my favorite professors through a mixture of immense topical knowledge with dry wit, his lectures provided an exceptional historical background for future learning and critical thinking. When covering the topic of ancient civilizations in Mesopotamia, the Persian Gulf featured in the topical discussion to a fair extent. (Un)fortunately, we didn't cover any sort of historiography on the subject of the gulf's geography.
The depth of the modern gulf does not exceed 90m, which is helpful since sea levels rose by about 90m when the glaciers from the last ice age melted. The Persian Gulf of the time was likely a fertile valley, but there was no recorded history at that point. The Sumerian great flood (an early analogue to the Biblical tale of Noah) is likely unrelated to the inundation (or Deluge, if you're still going all Biblical on me) of the Persian Gulf. The gulf sits at the collision zone of the Eurasian and Arabian tectonic plates which still periodically undergo tectonic activity related to orogeny (that is: mountain upheaval and usually accompanying subsidence somewhere else).For quite a while the historical coastline of the Persian Gulf was believed to have been between about 200 kilometers to the northwest of its present position. An archeological geologist named Jacques de Morgan theorized around 1900 that the Persian Gulf had slowly been filling in with sediment deposited by the Tigris, Euphrates, and Karun rivers. He suggested that the Tigris and Euphrates emptied into the gulf without forming a confluence (the Shatt al-Arab estuary (or the Avrandrud, if you're Persian - not to be confused with the Evinrud)), and that the Karun river's sediment formed a series of shoals, which eventually built up into the modern shoreline. Through an in-depth survey of archeological sites in Mesopotamia, de Morgan hypothesized that the coast of the Persian Gulf would have been near Baghdad in the 4th millennium BC... Never mind that his use of historical sites relied on his own survey of historical voyages whose point of origin we still don't definitively know (turns out you can say you've found anything if no one knows the actual location).
There are a few problems with de Morgan's assertion (besides his mélange of potentially made-up historical sites). Much of the rock in the area appears to be from freshwater sediment. There's also the problem of Lake Hammar in southeastern Iraq which miraculously hasn't really filled with sediment and wasn't there six thousand years ago. While sedimentary accretion is an accepted geological phenomenon, de Morgan was missing a few important bits of information (mostly the geology of his archeological geology).
The predominant theory behind the coastline of the Persian Gulf seems to still be Lees and Falcon's subsidence theory. With their fancy use of geological sampling, they hypothesized that the Persian Gulf had intermittently undergone (and continues to undergo) subsidence, which counteracts the silt deposits to a great extent. Iraq collides with Persia building mountains, but the creation of mountains requires a complementary subsidence zone. So, the story of Noah had it wrong: the land wasn't being flooded by water, the water was being flooded by land (...and was slowly sinking to cover it up, like some geologist-fantasized episode of CSI). Sure, Noah's flood is supposed to be from rain and rivers overflowing, but you can't have quality jokes and accuracy, what do you think this is the Daily Show? Through the use of aerial photography and charts from the 1800s, Lees and Falcon determined that the primary coastal change was a migration of the Shatt al-Arab's output further to the northeast. Subsidence and silt deposits have resulted in some ancient sites buried under a substantial depth of sediment (and occasionally water) as the shoreline meanders northeast. Or maybe Sumerians were just subterranean, Tolkien-esque dwarves with gills. So maybe in a few millennia the main river outlet into the Persian Gulf will be in Iran and we can avoid squabbles about preferred geographic names. Or half of the region will be buried under ten meters of silt, and everyone will turn into Morlocks. Either way I see a great future for the science fiction community and historians. I preemptively dub it historical futuristic science fiction.
Now we just need to work on renaming Lake Michigan to Lake Wisconsin.
