... I had often wondered how deep
Beleriand actually sunk, since
Lindon was still there? Or
Numenor? If scuba gear existed in MA, could one do a rec dive and see them?
That would probably have been one issue that also had Karen Wynn Fonstad, as a professional geographer and cartographer, scratching her head: assigning to the actions o the
Valar things that she knew in the real world to be the effects of plate tectonics - and never mind the divine intervention by
Eru in the sinking of
Númenor and the flat world made round (something JRRT was dissatisfied with late in life, among other issues he saw, leading him to beging a fairly massive revision of his mythology, now seen by him as a partially garbled "
Mannish tradition" - this has been and is being discussed in other threads).
The published Silmarillion is notably silent on
dates, especially about the last decades after the
Fall of Gondolin, last of the Elven strongholds on
Middle-earth to fall. Robert Foster, in his "Complete Guide to Middle-earth", latest edition making reference to source book editions published in 2002, has in it as Appendix A "A Chronology of the
First Age." Last "certain" date in it is 511, Fall of Gondolin.
Tuor and Idril are surmised to have left Middle-earth c. 543, and Foster assumes the First Age must have come to an end around the year 600. When exactly
Eärendil finally made it
Valinor, how long the mustering and transfer of the hosts of the West from Valinor to Middle-earth took, and how long (years, perhaps decades) the
War of Wrath was then actually fought might be found in scraps hidden in "History of Middle-earth" by Christopher
Tolkien, I don't know. But for an area as huge as Beleriand and surroundings, basically everything west of the
Blue Mountains which stand on the western shore of
Eriador starting with the
Second Age, to be sunk certainly has no parallel in actual geological history - unless you go into millions or even tens and hundreds of millions of years. There are
places, the best researched ones probably in the Mediterranean. like the port of Alexandria in Egypt in antiquity, which have sunk below sea level by plate tectonics, to depths to be reached by scuba divers, professional underwater archaeologists at least. For Beleriand, there is Tol
Morwen, "Morwen's Isle", with the burial mound of Morwen
Eledhwen and her son
Túrin Turambar, which was not buried under the seas at the End of the First Age but remained above sea level. At the end of the "
Akallabeth", fourth part of the published Silmarillion after
Ainulindalë,
Valaquenta and
Quenta Silmarillion there is the statement: "Among the Exiles [from drowned Númenor] many believed that the summit of the Meneltarma, the Pillar of Heaven, was not drowned for ever, bur rose again above the waves …" because of the Hallows of Eru on its peak. Seems to have been a misguided belief, as no on ever found the small island that the summit now formed.
