how did middle-earth evolve in the fourth age?

[Elven-Maiden]

The Encyclopedia of Arda has a very intersting article about the Fourth Age here

The most interesting is this though:

Although we have no records of the later Fourth, or any following Age, Tolkien makes a brief allusion to the future of Middle-earth in a letter written in 1958: "I imagine the gap [between the Fall of Barad-dûr and modern times] to be about 6000 years; that is we are now at the end of the Fifth Age, if the Ages were of about the same length as S[econd] A[ge] and T[hird] A[ge]. But they have, I think, quickened; and I imagine we are actually at the end of the Sixth Age, or in the Seventh."

Hope that helps [img]smilies/smile.gif[/img]