Abadan, is a rather common artifact of a river. It a river delta islet built up by silt. I studied that area when I use to teach about the military
actions there in Gulf War I (Iraqi-vs Iran). Sedimentary islands built of silt and loaded with water are a bad place to have a "bottomless pit". I
would also note that that name is a modern one. Place on it by the British in 19th century when surveying the (1819 I believe) area during their war
with the what later became the United Arab Emirates (piracy).
What it was called 4,000 years ago is interesting, even 2,000 years ago it had another nane - because back then it didn't exist. The shore line
existed to the NW of that position.
Eridu one of the first Sumer cities was built on the river near the seacoast. It is now inland.
[edit on 19/7/08 by Hanslune]