Is there any meaning to the ages of the Years of the Tree?

Question

It is said in The Silmarillion that Melkor was a prisoner for "three ages" before he had another trial and was released. It is estimated that this was about 2,900 years; see, e.g., this related question.

What I didn't manage to understand from the answers to this question, as well as the sources online cited, is this: was there any meaning to these ages?

The Ages that came later - the First Age, the Second Age, the Third Age - were divided according to big events that occurred. Was this the case here, or were these 'ages' just a system of measuring time?

The latter seem more likely, since Melkor was sentenced to 3 ages of prison - it'd be rather odd if his punishment depended on some arbitrary event occurring deemed special enough to start a new age. But I'm not sure.

EDIT: Again, this is not a duplicate of this related question, since I'm asking for the meaning of the ages, not their length, which I already know.

Answer 1

In this context "age" is just a unit of time, and does not mean the same thing as "First Age", "Second Age", etc.

The length of the time in this passage of the Silmarillion was taken from the Annals of Aman.

And the Valar doomed Melkor there to abide for three ages of Valinor, ere he should come forth again to be tried by his peers, and sue once more for terms of pardon. And this was done, and peace returned to the kingdom of Arda; and this was the Noontide of the Blessed Realm. Yet many evil things yet lingered in Middle-earth that had fled away from the wrath of the Lords of the West, or lay hidden in the deeps of the earth. For the vaults of Utumno were many, and hidden with deceit, and not all were discovered by the Valar.
_{The Annals of Aman - 1100 The Chaining of Melkor}

Earlier in the Annals of Aman an "Age of the Valar" is defined as 100 Valian Years:

Thereafter the Valar counted time by the ages of Valinor, whereof each age contained one hundred of the Years of the Valar; but each such year was longer than are nine years under the Sun.
_{The Annals of Aman - Of the Beginning of Time and its Reckoning}

And a Valian Year is defined as 84,000 Sun hours, or 9.582 Sun years:

But as for the Years of the Trees and those that came after, one such Year was longer than nine such years as now are. For there were in each such Year twelve thousand hours. Yet the hours of the Trees were each seven times as long as is one hour of a full-day upon Middle-earth from sun-rise to sun-rise, when light and dark are equally divided. Therefore each Day of the Valar endured for four and eighty of our hours, and each Year for four and eighty thousand: which is as much as three thousand and five hundred of our days, and is somewhat more than are nine and one half of our years (nine and one half and eight hundredths and yet a little).
_{The Annals of Aman - Of the Beginning of Time and its Reckoning}

So an "Age of the Valar" is then 958.2 Sun years, and Melkor spending three ages would thus be about 2,875 years.

It should also be noted that this chronology all reflects the way Tolkien saw things in 1951. In previous versions Melkor was said to be condemned for seven ages (which would have then been 7,000 sun years), and while I'm not sure if Tolkien later kept the "three ages" thing, he would later decide that a Valian Age was 144 Valian Years and that a Valion Year was 144 Sun Years (which would then make three ages equal to 62,000 sun years.)

Answer 2

According to the notes in 'Annals of Aman', found within the 'Morgoth's Ring' volume of History of Middle-Earth:

(i) According to the Reckoning of the Trees

12 hours (a full flowering of both Trees) = 1 day

1,000 days = 1 year

100 years = One Age of the Valar

(ii) Relation of the Reckoning of the Trees to the reckoning by the Sun

1 hour of the Trees = 7 hours of our time.

1 day of the Trees = (7x12) 84 hours of our time.

1 year of the Trees = (7x12,000) 84,000 hours of our time.

There are (365.25x24) 8,766 hours in a Sun Year, and thus: 1 year of the Trees = (84,000/8,766) 9.582 Sun Years.

Answer 3

The Answer you linked to said roughly:

1 Age = 100 Valar Years

1 Valar Year > 9 Middle Earth Years. I have no idea if another, more precise figure was given or could be calculated elswhere (like 9.75 years). But we can infer that it was not (quite) 10 years.

So it is a simple math problem. If 3 Ages are more then 300*9 Middle Earth Years:

• 300*9 is 2700 Years
• 300*10 is 3000 Years
• 2900 would mean 9 and 2/3 of a Middle earth year/Valar Year