thank you very much..

Another way people find age of the earth by taking chondrite into consideration which represents the bulk earth composition. but how can we be so sure about that chondrite representing bulk earth composition.?

Partha, you better read something about meteorites. Attached is a good paper for you to read. Also visit the website below for more information on chondrules (the material making up the chondrites)

http://ads.harvard.edu/books/chto/toc.html

Thank you perera

Dating about 70 meteorites gave a range of ages between 4.5 and 4.6 E 9 years.

with about 4.7 billion years as a maximum.

An alternative method is to use the recession rate of the Moon away from the

Earth, but it currently measures the surface to surface change in distance each

year, not the center to center distance change.

The change in the center to center distance divided by the average distance,

is proportional to the change in the time ( 1 year ) divided by 2 times the total

elapsed time, which is also proportional to the change in the mass, divided by

the total mass.

The changes are in parts per billion. By this method I calculated

4544.40 +/- 25.98 million years. This time is within range of the

much simpler to remember 4567 E 6 years.

Another method is the calculated cyclicity of extinction events.

The cycle is 186.62 million years per cycle and the Earth finished cycle 24

about 65.50 million years ago. 24 x 186.62 + 65.50.

The Moon is in cycle 23 so it is 4285.20 million years old more or less.

Thank you Micheal.

Michael,

the relationship between the cyclicity of extinction events and the age of the earth is not clear to me.

The theory is that the Earth and the Solar System are part of the

Sagittarius Galaxy which is spinning through the Milky way Galaxy, so

the Solar system " passes through" the various arms of the Milky way

Galaxy repeatedly at regular intervals that are spaced irregularly in time.

This is where you order a copy of the wall chart:

" A CORRELATED HISTORY OF THE EARTH "

From Pan Terra Inc.

The Author's theory is that the Earth passes through Each of the

Arms of the Milky Way Galaxy in the sequence. I will use the Author's

sequence because it uses mostly rounded whole numbers.

The last cycle was:

D: 180 MYA, E: 146 MYA, F: 132 MYA, G: 115 MYA, A: 66 MYA, B: 34 MYA,

C: 14 MYA < Now > D: 6.6 million years in the future.

The " A " extinction events seem to be the biggest ones:

66 MYA, 66+ 186.6 MYA , 66 + ( 2 x 186.6 ) MYA, etc.

That cause the highest death rates.

The Earth is not very good a preserving extinction events past the last three

or four cycles, because the Earth was covered with moving glaciers between

about 812 and 630 million years ago. Moving glaciers act like

bull dozers and grind most of the evidence away. The hydro-logic cycle

also is good at moving materials from one area to another from higher

elevations to lower elevations.

These bigger extinction events are associated with the largest impact craters

that are well over 100 km in diameter. Some also are accompanied by

flood basalts, and some by dramatic downward changes in ocean levels

such that reefs die, and oceans become anoxic.

If this process was underway when the Solar System was forming, and

planets were younger, the collisions with space debree were far more

powerful, as the debree was much larger. Both the Earth and the Moon

formed due to large collisions, but they formed at different times, when

passing through two different arms of the Milky Way Galaxy.

The questions then become which two arms ?

How many whole cycles have passed for Each Planet ?

How far into the next cycle has each cycle planet progressed ?

What are the upper and lower limits of the duration of each cycle ?

What pair of simultaneous equations can be made of the form:

N cycles plus C1 , and, N +1 cycles plus C2 ?????

By Guess work, the cycles are between 186 and 187 million years

per cycle. By testing various combinations that correlate to the age of the

Earth and Moon calculated from the rate at which the Moon moves away

from the Earth, you can get an " N " and a " C1 " for the Moon, then test

an " N + 1 ", and a " C2 " for the Earth.

Since the age of the Earth is known fairly well know from the analysis

of the ages of 70 meteorites to be less than 4570 million years old, this

really limits how many values of N + 1 are possible when you subtract

a value of C2 that is between 65 and 66 million years, and will give a number

that is between 186 and 187.

The best value for C2 is about 65.50 million year ago: that is

CHICXULUB, MEXICO with a 180 km diameter impact crater, and

the Dinosaur extinction Event , then if you go back between 186 and 187

million years before that, you get the End of Permian Extinction Event,

where the majority of the sea life went extinct when the ocean levels suddenly

dropped over 80 meters. The Ocean Basins also started forming, and the

magnetic reversals locked into the newly forming ocean floors also commenced.

So now we calculate: 4570 - 65.50 = 4504.5 / 186.5 = 24.15 ( too big )

because we are looking for a whole number less than 24.15, most likely

it will be 24.0

We can go thru lots of possibilities, but eventually I came up with:

186.62 x 24.35109 = 4544.384 million year old which is close to

my prior calculations of 4544.40 million years.

And 65.51 / 186.62 = 0.35103 which is close to 0.35109.

Now we concentrate on the age of the Moon which is generally considered to

be the result of an impact of an object with the Earth, so the

Moon has to be younger than the Earth, so it has to be younger than

4544.40 million years old.

We now look at the calculations for the Lunar recession rate where the

change in the distance divided by the distance is proportional to

the change in the time divided by the Lunar elapsed time.

By a couple of different methods I calculated that the Moon needed to

be between 4285 and 4385 million years old. Dividing 186.62 into these numbers

gives a whole number between 22.96 and 23.497.

Using 23 x 186.62 gives 4292.26 , but as it turns out the Moon is about 6.6

million years short of is 23 Birthday. 4285.66 / 186.62 = 22.96463 cycles

180.02 / 186.62 = 0.96463

About 180 million years ago the Earth started forming new ocean floor

at a far faster rate than it was forming between 251 and 253 million years ago.

This corresponds with a D : 180 MYA impact event.

The Earth then formed in and " A " impact event, and the Moon

formed in a " D " impact event. They both formed in collisions,

but they formed with collision in two different arms of the

Milky Way galaxy, about 258.72 million years apart.

258.72 - 186.62 = 72.1 million years. 72.1 - 6.6 = 65.50

This means that 6.6 million year in the future, it will be

72.1 million years since the Chicxulub Impact Extinction Event, and the

Moon will be at the Moons 23rd Birthday while the Earth will be

at cycle 24 and ( 72.1 / 186.62 ) = 24.386346586 cycles old.

So what is the time lapse between A and D ? It is 65.5 + 6.6 = 72.1

What is the difference in the age of the Earth and Moon ?

186.62 + 71.2 = 258.72 million years.

or

4544.38 - 4285.66 = 258.72 million years.

258.72 - 6.6 = 252.12 MYA ( Permian Extinction Event )

252.12 + 186.62 = 438.74 MYA ( Boundary between two time periods )

252.12 + 186.62 + 186.62 = 625.36 ( the Glaciers melt and the

larger life forms start to evolve in the oceans ).

252.12 + 3 x 186.62 = 811.98 ( the beginning of snow ball earth ).

Any way that is the long and the short of the math of the Earth and the

Moons cyclicity.

A very interesting speculation, but not in accordance with the geological data on major extinction events so far known.

The Author of the wall chart,

A CORRELATED HISTORY OF THE EARTH

came up with the 186 million year cycle, I just

applied the math to it to make it fit my

prior calculations from Lunar recession rate

in millimeters per year when you add together

the actual measured recession from surface to surface

of 38.2 mm per year to the average increase in

the elevation of the surface of the Earth of

about 4.15 to 4.17 mm per year. which is

42.36 mm plus or minus 0.01 mm per year.

Then you have to do a mass ratio correction of

81.30059122 / 82.30059122.

The annual change in the distance divided by the

average distance is proportional to the

change in the time divide by ( 2 x the elapsed time )

which is about 1 part in 9.2 billion.

If we could use the Sun and Jupiter to measure the recession rate,

it would give a more accurate value of the total age.

For now we will just have to settle for the Earth and the Moon,

or the Earth and Mars as a means of estimating The Age of

the Planets.

In Mathematics it can be expressed as a limit statement.

In the Limit as the age of the system becomes very old,

( billions of Years ), the changes in the system will be proportional to

either one over the age of system ( it there is one change ), or

one over two times the age of the system if the system is sharing the

changes between two partners, as in the Earth and the Moon.

If there was a much larger difference in the size of the Earth and Moon,

then no correction for mass ratio would be needed.

If you do not like the 4544.40, and prefer the 4567, then the cycle

would be : 4567 / 65.5 = 4501.5, then divide by 24 = 187.5625,

but this is a little too big to match the Silurian - Ordivician Boundary

at 439 MYa 439.0 - 65.5 = 373.5 / 2 = 186.75 MY per cycle.

Realistically there should be some variability in the cyclicity, as

space rocks do not collide with the Earth exactly on schedule.

There should be numerous near misses, and some hits with

other planets that may use up available resources. The Earth

may even get lucky and skip an occasional extinction.

About 6.6 million years in the future, our descendants may have

to deal with this problem.

From the earth sciences point of view these calculations are not easily applicable to the very complex problem of mass-extinctions between 570-12 ma, where we have sufficient evidence to speak about MA. If you consider the main events with >10% extinctions there is no remarkable periodicity. Moreover, there is no evidence for impacts for all cases yet.

Well, we have to start with the age of the oldest rock known, which is a Canadian quartz diorite that is 3.92 billion years old as determined by U-Pb zircon dating. This implies to me that a plate tectonic framework was already in place by that time. It took time for the plate tectonic framework to be established to get such an acidic igneous rock. Secondly, before that, the solid Earth had to be established and its layered structure had to be in place. This is largely a gravatational arrangement that involved very hot liquids and very dense rocks. Paul Lyons.

very dense solids too. It is easy to see that the time for establishing the layered structure of the Earth and its plate tectonic framework took as much as a billion years.

Jörg Hausmann is right from the first beginning. The age conclusion is inferred from dating. Quite a few lunar and meteorite samples were dated older than 4.5 billion years. Since bearing the same origin with moon and meteorite as members of the solar system, the earth is thus inferred as old as the other members. Therefore, the age of the earth now is generally accepted as 4.6 By. However, the oldest terrestrial rock was dated only around 4.0 billion years old. Which means that the rock record of the earliest 0.6 billion years on earth is totally missing. Why is that ?

It is also generally believed that the earth was initially a hot melt . Through cooling, an unstable thin- layered crust was repeatedly formed and torn apart to be recycled back into the earth's mantle. This is probably the reason for the 0.6 By. missing rock record.

In contrast with what Eason Hong said, the oldest terrestrial rocks (i.e. zircons from the Yilgarn craton, Westen Autsralia) are actually dated at 4.4 Gyr (= Hadean age) (as Jorg Hausmann already stated). Obviously older rocks are not retrieved, because the earth's crust took some million years to form and solidify. Before this date the earth's surface consisted most likely of a magma ocean.

Interestingly, this dating method has been doubted for some reasons because of intracrystalline Pb mobility due to radiation damage. Recently, however, the dating method been confirmed in Nature of Geoscience (http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2075.html) to be correct by atom-probe tomography. I can advice to read this paper for those interested in the topic ;)

Eason Hong asked about the first 0.6 Billion years.

You have to look in some very specific places on the surface of the Earth

to find very old geology. It would be in a very small portion of the 7% of

the Earth"s Surface area that is of Archaeon Rock. There are small frag-

mented areas on every continent.

If you do the math related to the " MOST UNLOVED TECTONIC THEORY "

that of growth and expansion of planets, there was never more than

about 7.14 % of the current planets surface area in the Archaeon to

begin with, so still having 7% remaining is remarkable.

You simply take the square of the ratio of the initial radius divided by

the current radius to get the decimal original surface area.

That is ( 1703.4 / 6372.4567 ) ^2 = ( 0.2673 ) ^2 = 0.07145.

This is about 7.145 % in the lower limit ( two sources of planetary growth ).

The upper limit is about ( 1713.8176 / 6372.4567 ) ^2 = 0.07233.

This is about 7.233% in the upper limit ( one source of planetary growth ).

To imagine that the planets actually grow larger at very slow rates

makes people very nervous, because it is not consistent with the

current paradigm of Plate Tectonics that says all the growth took

place in a very short time as all the other planets formed,

but reason and logic say that growth supply of materials follows

exponential decay curves of availability. The biggest space rocks

tend to be used up first, then progressively smaller and smaller

space rocks and debris are used up, and eventually you get down to

particles that the size of pea gravel to dust sizes, and the Earth is

still collecting these smaller materials.

But the surface area math of why there is and only ever was about

7 % seems to work out rather well. It is also still there in that it was protected

from glacial removal processes by the thick layers that were over these older

layers. Of course that begs the question of why are they all exposed now,

or is this rock known from drilling core holes to find oil and gas ?

It might be possible that one could find older zircons than 4.4 billion years,

but you might need to drill hundreds of core holes very deep into the

Archaeon Rocks, to find just one sample that is older.

I am kind of amazed they found one place that old.

It is just easier to sample meteorites, some of them are a little older.

up to 4.567 Billion years old.

Lunar recession rates give 4.544 Billion years old, and cyclical

extinctions give 4.538 Billion years, but with a fairly big plus or minus.

The date range of 70 meteorites is probably the best way to determine the

earth's age because as more and more meteorites are tested in the future,

it will create an age distribution curve with a peak at some value, and a fairly

narrow plus or minus range either side of the peak.

The assumption will be that the material used to form the Earth came from

one or more Super Nova explosions that sprayed materials of a

specific age , that accumulated to form the Sun and Planets. Perhaps the

Sun and Planets were in a very fast accretion phase between 4.567

Billion, and 4.4 Billion years ago, so it will be hard to find any materials

older than 4.4 billion years ago because it would be deep inside the

Earth.

Only time will tell.

The zircons with 4.4 By came from TTG rocks, and indicates there was a oldest continental crust that we don't know its scale. However we have no evidence to understand the TTG rocks formed at a contienetal margin (a pre-existing ocean) or just a patial melting from mafic terrane.

Yes Matin, what happend from a magma ocean scenario to production of felsic crust - a few 100myrs, this is important..