How old is Middle-earth?

Question

I'm surprised that there isn't a duplicate for this.

This question about plate tectonics in Middle-earth got me thinking, that it is probably not old enough to have the lands shaped by geological processes. (As others explain in the answers that it not how middle earth was formed)

Generally, geological processes like mountain ranges rising take millions of years.

I tend to get confused about the early history of Arda, I believe there was a time before it existed as a physical world.

How long has Middle-earth existed as a physical entity?

Answer 1

There is an answer in Quora here. It's a nice summary, so I'm sharing it below.

To quote The Annals of Aman:

It is computed by the lore-masters that the Valar came to the realm of Arda, which is the Earth, five thousand Valian years ere the first rising of the Moon, which is as much as to say forty-seven thousands and nine hundred and one of our years.

That divides into 3500 Valian years (or 33,530 of our years) before the creation of the Two Trees, the 'Days without days'. Then 1495 years of the Trees (14,322 of our years), 'the Days of Bliss'. Then five years (48 of our years) of Darkness.

Total 5000 Valian years or 47,901 solar years from the Creation to the rising of the Sun and Moon.

The rest of the First Age was 590 solar years, the Second Age was 3441 years and the Third Age was 3021 years.

Grand total, up to the end of Lord of the Rings, 54,953 solar years.

In a letter written in 1958 Tolkien said that he imagined the gap between "the fall of Barad-dûr" and "our days" to be about 6,000 years.

Which would make Arda 60,000 years old, give or take a millennium.

That's from the most complete and detailed timeline Tolkien made, in the late 1950s. During the 1930s he was imagining the timescale to be about 20,000 years shorter.

By the 1960s he was of the mind that he should write that the universe was 14 billion years old and Arda itself 4.5 billion years old, and the whole story of its creation by the Valar, Varda making the Stars long after the Earth itself was made, and the origins of the Sun and Moon, was merely a Númenorean myth — but he never fleshed out this idea in detail.

You can find the mentioned script in The History of Middle-earth, Vol. X: Morgoth's Ring, Part Two.

Also, Tolkien changed his mind constantly. He invented languages and drew maps and etc. It's natural that you feel confused.

Answer 2

Tolkien frequently changed his views of Middle-earth's history over the 50+ years that he spent writing it. Depending on which version of the texts one uses it could be anything from 30,000 years to something numbering well into the millions.

The first rigorous chronology emerged with the 1930's series of writings. (Quenta Noldorinwa and the early Annals). Note that in addition to changing around with the chronology, Tolkien would also change the Valian to solar year ratio.

1930's canon — 30,250 years

• 3,000 Valian years (= 30,000 solar years) from The Music of the Ainur until the rising of the sun.

  And even as they came the First Ages of the World were ended; and these are reckoned as 30000 years or 3000 years of the Valar; whereof the first Thousand was before the Trees, and Two Thousand save nine were Years of the Trees or of the Holy Light, which lived after and lives yet only in the Silmarils. And the Nine are the Years of Darkness or the Darkening of Valinor.
  _{Annals of Valinor (1930's)}

• 250 solar years from the rising of the sun until the end of the first age.

1937 canon — 30,597 years +/- miscalculation error

• 500 estimated Valian years (= 5,000 solar years) from The Music of the Ainur until the finished their world-making labors and decided to start actually measuring time. The number 500 is just a calculation of later loremasters.

  Time was not measured by the Valar, until the building of Valinor was ended; but thereafter they counted time by the ages of Valinor, whereof each hath 100 years of the Valar, and each Valian year is as ten years of the Sun now are.
  _{Annals of Valinor (1937)}

• 2,500 Valian years (= 25,000 solar years) from the building of Valinor until the rising of the sun.

  It is said that the Valar came into the world 30,000 Sun-years ere the first rising of the Moon, that is thirty ages ere the beginning of our time; and that Valinor was built five ages after their coming.
  _{Annals of Valinor (1937)}

• 597 solar years from the rising of the sun until the end of the first age.

1951 canon — 54,904 years + labor in halls of Ea +/- miscalculation error

• "Ages of labour beyond knowledge or reckoning in the great halls of Ea"

  After ages of labour beyond knowledge or reckoning in the great halls of Ea the Valar descended into Arda in the beginning of its being, and they began there their labour fore-ordained for the shaping of its lands and its waters, even from the foundations to the highest towers of the Air.
  _{Annals of Aman}

• 3,500 estimated Valion Years (= 33,530 solar years) from when the Valar entered Arda until time first started to actually be measured with the flowering of Telperion. The number 3,500 is just a calculation of later loremasters.

  It is computed by the lore-masters that the Valar came to the realm of Arda, which is the Earth, five thousand Valian Years ere the first rising of the Moon, which is as much as to say forty-seven thousands and nine hundred and one of our years. Of these, three thousand and five hundred (or thirty-three thousand five hundred and thirty of our reckoning) passed ere the measurement of time first known to the Eldar began with the flowering of the Trees.
  _{Annals of Aman}

• 1,500 Valian Years (= 14,322 solar years) from the flowering of Telperion until the rising of the sun.

  Thereafter one thousand and four hundred and five and ninety Valian Years (or fourteen thousand of our years and three hundred and twenty-two) followed during which the Light of the Trees shone in Valinor.
  _{Annals of Aman}

• 590 solar years from the rising of the sun until the end of the first age.

• 6,462 solar years of the second and third ages

1960 canon — 735,200 years + labor in halls of Ea +/- miscalculation error

• "Ages of labour beyond knowledge or reckoning in the great halls of Ea" (From 1951 chronology)

• 3,500 estimated Valion Years (= 504,000 solar years) from when the Valar entered Arda until time first started to actually be measured with the flowering of Telperion. This uses the 1951 chronology, but now Tolkien has modified Valian Years to each be equivalent to 144 solar years.

  In recording the events in Aman, therefore, we may as did the Eldar themselves use the Valian unit, though we must not forget that within any such 'year' the Eldar enjoyed an immense series of delights and achievements which even the most gifted of Men could not accomplish in twelve times twelve mortal years.
  _"Aman"

• 1,050 Valian Years (= 151,200 solar years) from the flowering of Telperion until the awakening of Men.

  If they awoke in VY 1050 that would give 40 VYs, or 5,760 Sun Years in which Melkor could have dealings with them and corrupt them, before his captivity.
  _{"The Awaking of the Quendi"}

• 80,000 solar years from the awakening of Men until Gregorian Calendar year 1960 of Tolkien's seventh age.

  The Atani entered Beleriand in 310 Bel. That is in the 22nd Sun-year of VY 1498. Men had then existed for 448 VYs + 22 SYs: i.e., 64,534 Sun Years, which, though doubtless insufficient scientifically (since that is only – we being in 1960 of the 7th Age – 16,000 years ago: total about 80,000), is adequate for purposes of the Silmarillion, etc.
  _{"The Awaking of the Quendi"}

Answer 3

TL;DR Tolkien had various versions and lengths he played with. Deciding between 3000 and 5000 Valian Years for the Ages of the Valar, deciding between 9.58, 10 or 144 Years of the Sun for each Year of the Trees. This gives us a range from 43000 years old to 733000 years old to millions of years.

---

The main thing missing in @apollo's answer is the fact she's quoted one continuum of Tolkien's Legendarium, that in which Tolkien uses slightly over 9 for the number of Years of the Sun in one Year of the Trees (approx. 9.58). Tolkien wrote many versions of the stories that conflict and contradict each other. This has created various continuums in which his tales lay intertwined, similar but not the same.

In the below quotes, AAm is the Annals of Aman, AV2 is the Annals of Valinor Part 2 (written pre-LotR)

As this sentence was first written in the draft text for the beginning of AAm (the rewriting of A V 2) it read: 'each such year is in length even as are ten years of the Sun that is now'; i.e., my father still retained the old much simpler computation going back through AV 2 (V.110) to AV 1 (IV.263). This was changed on the draft text to 'each such year is longer than are nine years of the Sun that is now'.
_{Morgoth's Ring}

From the above we can see that in the earlier legendarium, Tolkien had his mind set on 10 Years of the Sun (Y.S.) to one Year of the Trees (Y.T.). This only slightly extends the "age" of Middle-earth/Arda. That puts us the coming of the Valar about 3000 years earlier than in apollo's answer. So we see in this older version of the Legendarium Tolkien had intended it to be a slightly older timeline. Extending the length before the suns rise by about 3000 years (or 300 Valian Years)

Below we have further evidence of Tolkien using the 10 Y.S. = 1 Y.T.

five and thirty Years of the Valar (which is like unto three hundred and thirty-five of our years)
_ibid.

For well-nigh one hundred of the years of our time (though that be but ten of the Years of the Valar) they dwelt in Tol Eressea.
_ibid.

And even as they came the First Ages of the World were ended;(24) and these are reckoned as 30000 years or 3000 years of the Valar whereof the First Thousand was before the Trees, and Two Thousand save nine were Years of the Trees or of the Holy Light, which lived after and lives yet only in the Silmarils. And the Nine are the Years of Darkness or the Darkening of Valinor.

The above is interesting to note, as although it gives us further confirmation of the 10 = 1 rule, it also informs us of the fact in another version of the Legendarium the Ages of the Valar, before the rising of the sun only lasted 3000 years. As opposed to the version mentioned by apollo which lasted 5000 years. This would make the age of Arda around 43000 years old. A whole 17000 years younger than that which was proposed in Christopher's edits.

It was indeed at the landing of Fëanor three hundred and sixty-five long years of the Valar(1) since the Noldor had passed over the Sea and left the Teleri behind them. Now that time was in length well nigh as three thousand and five hundred years of the Sun.
_{The War of the Jewels}

In the War of the Jewels we get an example of the ~9.58 Y.S. = 1 Y.T. This seems to be the most accepted answer, as quoted on tolkiengateway, as well as elsewhere. Providing us with the ~60,000 year old Arda as seen above.

“In notes not given in this book, in which my father was calculating on this basis the time of the Awakening of Men, he expressly stated that 144 Sun Years = 1 Valian Year expressly stated that 144 Sun Years = 1 Valian Year (in this connection see Appendix D to The Lord of the Rings: 'It seems clear that the Eldar in Middle-earth ... reckoned in long periods, and the Quenya word yen... really means 144 of our years').

In other notes, Tolkien thought of 1 Y.T. to be equal to 144 Y.S. (likely due to the Elves' obsession with sixes and twelves). This would put the age of Arda at ~733000 years. With the Ages of the Valar taking up around 720000 of those years.

These longer years seems to be something Tolkien played with later in his life. Although I couldn't find a source for it, the Tolkien scholar, Michael Martinez, speaks of notes where Tolkien considered making Arda millions or billions of years old, which would allow for the reshaping of the world to fit what we have today.