8. Benoît de Maillet
1656 - 1738
Telliamed, 1748
“Let us not measure the
past duration of the
world by that of our own
years.”
Used decline in sea level
to obtain an age of two
billion years.
9. “chiefly intended to refute the ancient
notion, some have of late entertained,
of the eternity of all things; though
perhaps by it the world may be found
much older than many have hitherto
imagined.”
10. John Joly
1857 - 1933
“The quantity of sodium now
in the sea, and the annual rate
of its supply by the rivers,
lead, it will be seen, to the
deduction that the age of the
Earth is 99 million
years.” (1899)
11. Modern Salt “Clocks”
< 100 years: Al
< 1,000 years: Cr, Th, Ti, Fe
< 10,000 years: Ni, Si, Pb, Mn
< 100,000 years: Sn, Ba, Cu, Bi, Hg, Co
< 1,000,000 years: Au, Mo, Sb, Rb, Zn
< 10,000,000 years: Ag
< 100,000,000 years: Na, Mg, Li, Sr, K
12. Problems
Assumption of constant rate of influx across
geologic time known to be wrong.
Poorly estimated parameters: rates of erosion and
solution, rainfall, runoff, continental area, average
exposed rock composition over time.
Ignores movement of elements out of oceans,
movement which occurs at approximately the same
rate as influx. Therefore confuses residence time with
accumulation time.
14. Epochs of Nature
Formation of molten Earth
Cooling to hand-hot
temperature
Enveloped with global sea
Volcanic activity
Emergence of land animals
Tectonic activity forms the
land masses
Appearance of humans
15. Age of the Earth
First application of
experiment to problems
of geology
Cooling of metal spheres
of various diameters
Estimated 96,670 years
for Earth to cool to
current temperature.
16. William Thomson
Lord Kelvin, 1824 - 1907
Professor of Natural Philosophy at
Glasgow (1846 - 1899)
Kelvin scale (1848)
Second Law of Thermodynamics
(1851)
First transatlantic cable (1866)
Peerage (1882)
President, Royal Society (1890 – ‘95 )
17.
18. Kelvin’s
Cooling Argument
All energy transformations result in loss of energy as
heat (1852)
“Within a finite period of time the Earth must have
been, and within a finite period of time to come the
Earth must again be, unfit for the habitation of man
as at present constituted, unless operations have
been, or are to be performed, which are impossible
under the laws to which the known operations going
on at present in the material world are subject.”
19. 1862
“It seems, therefore, on the whole most probable
that the sun has not illuminated the earth for
100,000,000 years, and almost certain that he has
not done so for 500,000,000 years. As for the
future, we may say, with equal certainty, that
inhabitants of the earth cannot continue to enjoy
the light and heat essential to their life, for many
million years longer, unless sources now unknown
to us are prepared in the great storehouse of
creation.”
20. 1864
“For eighteen years it has pressed on my mind, that
essential principles of Thermo-dynamics have been
overlooked by those geologists who
uncompromisingly oppose all paroxysmal
hypotheses, and maintain not only that we have
examples now before us, on the earth, of all the
different actions by which its crust has been
modified in geological history, but that these actions
have never, or have not on the whole, been more
violent in past time than they are at present.”
21.
22. Assumption: The earth is a
warm, chemically inert planet
that is cooling.
Assumption: It can be modeled
as an infinite plane of infinite
thickness.
Assumption: Heat loss is
through conduction from the
center.
23. Kelvin’s Estimate
“I think we may with much
probability say that the
consolidation cannot have taken
place less than 20,000,000 years
ago, or we should have more
underground heat than we actually
have, nor more than 400,000,000
years ago, or we should not have
so much as the least observed
underground increment of
temperature.”
24. Samuel Haughton
1821 - 1897
Applies Kelvin’s
methodology and got an
answer of 2.298 billion
years.
25. Clarence King
1842 - 1901
First director of the US
Geological Survey (1879 –
’81).
24 million years (1893)
26. Kelvin’s curve
King’s curve
Parameters:
T: Initial temperature
g: Thermogradient
t: Cooling time
27. Kelvin 1897
“During the thirty-five years which have passed since I
gave this wide-ranging estimate [20,000,000 –
400,000,000 years] experimental investigation has
supplied much of the knowledge then wanting regarding
the thermal properties of rocks to form a closer
estimate of the time which has passed since the
consolidation of the earth, and we have now good
reason for judging that it was more than 20 and less than
40 million years ago, and probably much nearer 20 than
40 … I am not led to differ much from [King’s] estimate
of 24,000,000 years.”
28. By 1900
Physicists seemed to be limiting the age of the Earth
to around 25 million years.
For biologists, this wasn’t a problem as they
generally didn’t subscribe to an evolutionary
process that required long periods of time and
instead allowed for directed evolution.
This was, however, a problem for the geologists
who felt that long periods of time were needed for
formation of the Earth as we see it today.
29. Thomas Henry Huxley
“The argument is simple enough. Assuming the earth to
be nothing but a cooling mass, the quantity of heat lost
per year, supposing the rate of cooling to have been
uniform, multiplied by any given number of years, will be
given the minimum temperature that number of years
ago. But is the earth nothing but a cooling mass… and has
its cooling been uniform? … I do not think it can be denied
that such conditions may exist, and may so greatly affect
the supply, and the loss, of terrestrial heat as to destroy
the value of any calculations which leave them out of
sight. ”
30. T.C. Chamberlain
1899
“The fascinating impressiveness
of rigorous mathematical
analyses, within its atmosphere
of precision and elegance,
should not blind us to the
defects of the premises that
condition the whole process.
There is perhaps no
beguilement more insidious and
dangerous than an elaborate and
elegant mathematical process
built upon unfortified premises.”
31. T.C. Chamberlain
1899
“What the internal
constitution of the atoms
may be is yet an open
question. It is not
improbable that they are
complex organizations and
the seats of enormous
energies.”
32. Rutherford & Soddy
1903
The energy from radioactive decay “must be
taken into account in cosmical physics. The
maintenance of solar energy, for example, no
longer presents any fundamental difficulty if the
internal energy of the component elements are
considered to be available, i.e., if processes of
sub-atomic change are going on.”
33. Ernest Rutherford
1904
“I saw [Kelvin] sit up, open an
eye and cock a baleful glance at
me! Then a sudden inspiration
came to me, and I said Lord
Kelvin had limited the age of
the Earth, provided no new
source of heat was discovered.
That prophetic utterance refers
to what we are considering
tonight. Radium! Behold!”
35. Problems with Kelvin’s Method
Parameters are poorly known (conductivity of
rocks; thermal gradient; initial temperature of
the Earth; heat released upon crystallization;
exact composition and structure of the Earth).
Considers conduction but not convection.
Ignores other sources of heat:
36. Sources of Heat
Heat left over from the formation of the
Earth, e.g. gravitational energy from compaction,
mechanical energy from meteor impacts, chemical
energy from the formation of the Fe-Ni core.
Energy from contraction due to cooling
Energy from ongoing core expansion
Radioactivity
42. Constant Decay
The radioactive decay rates of nuclides used in radiometric
dating have not been observed to vary since their rates
were directly measurable, at least within limits of accuracy.
This is despite experiments that attempt to change decay
rates.
There is insufficient energy in geological processes to affect
the decay rate.
The half-lives of radioisotopes can be predicted from first
principles through quantum mechanics. Any variation would
have to come from changes to fundamental constants.
43. Ernest Rutherford
1906
“The helium observed in the radioactive
minerals is almost certainly due to its
production from the radium and other
radioactive substances contained
therein. If the rate of production of
helium from known weights of the
different radioelements were
experimentally known, it should thus be
possible to determine the interval
required for the production of the
amount of helium observed in
radioactive minerals, or, in other words,
to determine the age of the mineral.”
44. Arthur Holmes
1890 - 1965
“The association of lead with
uranium in rock-minerals and its
application to the measurement
of geological time.” Transactions of
the Royal Society (1911)
Used U-Pb methods to date
rocks from Ceylon to
1,640,000,000 years – the oldest
rocks then known.
48. By 1950
The geologists had come to a lower limit for the
age of the Earth of 3.35 billion years.
The cosmologists however thought the
universe was 1.80 billion years old.
We have a problem. Who is right?
49. Modern Estimates
Oldest metamorphic
rocks: 3.85 billion years
Age of crystallization of
oldest mineral: 4.40
billion years
65. “Heavier-than-air
“X-Rays are a hoax” flying machines are
impossible.”
“There is nothing
new to be discovered in
physics now. All that remains is
more and more precise
measurement
66. “Heavier-than-air
“X-Rays are a hoax” flying machines are
impossible.”
“There is nothing
new to be discovered in
physics now. All that remains is
more and more precise
measurement
Editor's Notes
kelvin &#x2013; a (thermodynamic) revolution against a (geological) revolution that would require another (radioactive) revolution to get the right answer.
up to 1900
1650
published after death / slow development by natural processes (Neptunian)
1715 - long-term data was required / collected &#x201C;for the benefit of future ages.&#x201D;
1909: 150 million years. / Invented radium treatment (&#x201C;The Dublin Cure&#x201D;) for cancer
35 of 50 volumes with supplements, one of which (1778) discussed geological history
Privately believed 3 billion years.
Attended Glasgow University at age of 10 to study mathematics and then went to Cambridge. Upon retirement had over 600 articles and 70 patents.
Ironically, the only one of these assumptions that actually holds is the second one!
But &#x2026; 98 million years is most likely.
Developed equations for determining humane hangings. / Opposed Darwin &#x2013; so not doing this to help
Died here in Phoenix of TB
president of the Geological Society, 1869. Points out the uncertainty in both assumptions and data.
Columbia geologist / Elegant models are only as good at the premises and data that are entered into them. / The engineers who say that bees cannot fly.
Becquerel had discovered radioactivity three years earlier &#x2013; much was to be discovered
TC for the win!
35 year old, giving talk in London. Kelvin was in the audience
importance of convection and radiation (in crust & core)
This is a statistical claim about any given atom in a sample. Given the large number of atoms in even a small sample, the claim hold nicely / decay constant is probability of given atom decaying per unit time / Soddy & Rutherford 1902
This is a statistical claim about any given atom in a sample. Given the large number of atoms in even a small sample, the claim hold nicely / decay constant is probability of given atom decaying per unit time / Soddy & Rutherford 1902
Only a single variation in decay rate has been reproduced (that of 7Be) and that was a variation of only 0.18%, not enough to alter any clock (if there was one using 7Be)
&#x201C;One of the greatest pieces of geological literature ever published.&#x201D; (Peter Wyse Jackson, 2007
How do you test this assumption of a closed system? You don&#x2019;t just take a rock, any rock, measure some stuff, and come up with an age.
Meteor Crater / 50,000 years ago / 45 m wide rock weighing 300,000 tons moving at ~30,000 mph. / Impact ~ 2.5 megatonnes TNT (i.e. 150x Hiroshima) / 175 million tons of rock were moved and scattered over 100 sq miles. Everything up to 10 miles away was flattened. / 5.5 scale earthquake was produced.
Meteor Crater / 50,000 years ago / 45 m wide rock weighing 300,000 tons moving at ~30,000 mph. / Impact ~ 2.5 megatonnes TNT (i.e. 150x Hiroshima) / 175 million tons of rock were moved and scattered over 100 sq miles. Everything up to 10 miles away was flattened. / 5.5 scale earthquake was produced.
Meteor Crater / 50,000 years ago / 45 m wide rock weighing 300,000 tons moving at ~30,000 mph. / Impact ~ 2.5 megatonnes TNT (i.e. 150x Hiroshima) / 175 million tons of rock were moved and scattered over 100 sq miles. Everything up to 10 miles away was flattened. / 5.5 scale earthquake was produced.
Meteor Crater / 50,000 years ago / 45 m wide rock weighing 300,000 tons moving at ~30,000 mph. / Impact ~ 2.5 megatonnes TNT (i.e. 150x Hiroshima) / 175 million tons of rock were moved and scattered over 100 sq miles. Everything up to 10 miles away was flattened. / 5.5 scale earthquake was produced.
Meteor Crater / 50,000 years ago / 45 m wide rock weighing 300,000 tons moving at ~30,000 mph. / Impact ~ 2.5 megatonnes TNT (i.e. 150x Hiroshima) / 175 million tons of rock were moved and scattered over 100 sq miles. Everything up to 10 miles away was flattened. / 5.5 scale earthquake was produced.
Later became a pioneer of studying lead contamination
