It's the end of an era (but how did they know?)

[Selmo]

Originally Posted by hewhoarisesinmight

The ages of the sun all ended in great age defining events, .........

It's always puzzled me that the most significant event since the creation of the world was not chosen as the start of a new Age.
I refer, of course, to the complete re-shaping of the world following Numenor's rebelion against the Valar.

.