The Age of Earth
The Age of the Earth
• "Everything which has come down to us
from heathendom is wrapped in a thick
fog; it belongs to a space of time we
cannot measure. We know that it is older
than Christendom, but whether by a
couple of years or a couple of centuries, or
even by more than a millenium, we can do
no more than guess.
" Rasmus Nyerup, (Danish antiquarian), 1802
The Earth is Old
• By the mid 19th century geologist had
established beyond a reasonable doubt,
that the Earth was very old compared to
earlier Christian thought.
– Uniformitarianism.
– Developed geological time scale using the
principal of relative dating.
The question remained “How old is the
earth exactly?”
• Radiometric
dating allows
geologists to
assign absolute
ages to the
relative dates
established by the
geologic time
scale.
Geological Time scale
Principles of Radometric dating
•
The number of decay events observed in a rock sample
over time depends solely on how many radioactive atoms
are present.
–
•
This is why we can calculate constant half lives.
Decay rates are not affected by temperature, moisture, or any
other environmental factor.
Conclusion:
Radioactive isotopes function as natural clocks.
Principles of Radometric dating
1.
Uses unstable isotopes of naturally occurring
elements.
2.
The isotopes decay into either different
elements or different isotopes of the same
element.
3.
Each isotope decays at a particular and
constant rate, measured in half-life.
1.
One half-life is the amount of time it takes for
50% of the parent isotope present to decay into
its daughter isotope.
Measuring half-lives
• The analysis of a rock shows that it contains 25% of
the original parent radioisotpe. The half-life of this
parent isotope is 1000 years. How old is the rock.
A. 1000 years
B. 2000 years
C. 5000 years
D. 1.2 million years old.
• You are analyzing Moon rocks that contain
small amounts of uranium-238 which
decay into Pb-207 with a half-life of about
4.5 billion years. You determine that a
rock from the lunar highlands contains
55% of the original uranium and the other
45% decayed intoPb-207. How old is the
rock?
• A = 3.88 Billion years
• B= 5.18 Billion years
• C = 4.20 Billion years
Calculating Radiometric dates
Time
= ½ life
x
Log10
(
Current amount of Isotope
Original amount of Isotope
( )
Log10 1/2
)
Answer = A
Answer = 3.88 Billion years
Is Radiometric Dating
Accurate?
Nuclide
Half – life
Found in
nature?
Nuclide
Half – life
Found in
nature?
50
6.0 X 1015
Yes
244
Pu
8.2 X 107
Yes
2.4 X 1015
Yes
146
Sm
7.0 X 107
No
174Hf
2.0 X 1015
Yes
205
Pb
3.0 X 107
No
192
Pt
1.0 X 1015
Yes
236
U
2.39 X 107
Yes - P
115
In
6.0 X 1014
Yes
129
I
1.7 X 107
Yes - P
152
Gd
1.1 X 1014
Yes
247
Cm
1.6 X 107
No
123
Te
1.2 X 1013
Yes
182
Hf
9 X 106
No
190
Pt
6.9 X 1011
Yes
107Pd
7.0 X 106
No
138
La
1.12 X 1011
Yes
53
3.7 X 106
Yes - P
147
Sm
1.06 X 1011
Yes
135
3.0 X 106
No
4.88 X 1011
Yes
97
2.6 X 106
No
V
144
87
Nd
Rb
Mn
Cs
Tc
187
Re
4.3 X 1010
Yes
237
Np
2.14 X 106
Yes - P
176
Lu
3.5 X 1010
Yes
150
Gd
2.1 X 106
No
232
Th
1.40 X 1010
Yes
10Be
1.6 X 106
Yes - P
238
U
4.47 X 109
Yes
93
Zr
1.5 X 106
No
1.25 X 109
Yes
98
Tc
1.5 X 106
No
7.04 X 108
Yes
153
1.0 X 106
No
40
K
235
U
Dy
Nuclide
Half – life
Found in
nature?
Nuclide
Half – life
Found in
nature?
50
6.0 X 1015
Yes
244
Pu
8.2 X 107
Yes
2.4 X 1015
Yes
146
Sm
7.0 X 107
No
174Hf
2.0 X 1015
Yes
205
Pb
3.0 X 107
No
192
Pt
1.0 X 1015
Yes
115
In
6.0 X 1014
Yes
152
Gd
1.1 X 1014
Yes
247
Cm
1.6 X 107
No
123
Te
1.2 X 1013
Yes
182
Hf
9 X 106
No
190
Pt
6.9 X 1011
Yes
107Pd
7.0 X 106
No
138
La
1.12 X 1011
Yes
147
Sm
1.06 X 1011
Yes
135
3.0 X 106
No
4.88 X 1011
Yes
97
2.6 X 106
No
2.1 X 106
No
V
144
87
Nd
Rb
Cs
Tc
187
Re
4.3 X 1010
Yes
176
Lu
3.5 X 1010
Yes
232
Th
1.40 X 1010
Yes
238
U
4.47 X 109
Yes
93
Zr
1.5 X 106
No
1.25 X 109
Yes
98
Tc
1.5 X 106
No
7.04 X 108
Yes
153
1.0 X 106
No
40
K
235
U
150
Gd
Dy
Sr 87 / Sr86
Concordancy
2
4
6
Rb 87 / Sr 86
8
Sr 87 / Sr86
Concordancy
2
4
6
Rb 87 / Sr 86
8
Is Radioactive Decay Valid?
• Dating inner core of tree rings.
– Bristlecone pine live up to 6,000 years.
• Dating coral.
• Ice cores
– Differences between snow layers made in the summer
and winter (date the dust found in the layers)
• Dating varve layers.
– Seasonal variation in sedimentary layers deposited
underwater
• Dating historical artifacts that the dates are already known.
– A sample of acacia wood from the tomb of the pharoah
Zoser was dated. Zoser lived during the 3rd Dynasty in
Egypt (2700-2600 BC).
– Ancient Papyri with known dates. (Dead sea scrolls)
Is Radioactive Decay Valid?
• Compare radiocarbon results with the dates produced by
other dating methods,
– Agree with relative dating
– Uranium/Thorium dating (dating coral etc)
– Thermoluminescence (pottery, sediments),
– Obsidian Hydration (obsidian),
– Electron Spin Resonance,
– Amino Acid Racemisation dating (eggshell, bones).
Is Radioactive Decay Valid?
• An exponential decay is seen for short-lived isotopes with
half-lives of only a few days.
• For the decades they have been observed, the long-lived
isotopes also follow an exponential decay.
• The radioactive age of a rock layer is found using multiple
types of radioactive isotopes with different decay rates.
Parent Isotope
Stable Daughter Isotope
Half-life
Platanum-190
Osmium-186
690 billion yrs
Samarium-147
Neodymium-143
106 billion yrs
Rubidium-87
Strontium-87
48.8 billion years
Thorium-lead
Pb-208
14.1 billion yrs
Uranium-238
Pb-206
4.5 billion yrs
Potassium-40
Argon-40
1.25 billion yrs
Uranium-235
Lead-207
704 million yrs
Plutonium-244
Uranium-238
82 million yrs
Uranium-236
Thorium-232
23 million yrs
Iodine-129
Xenon-129
1.7 million yrs
Manganese-53
Manganese-55
370 thousand yrs
Neptunium - 237
Protactium-233
214 thousand yrs
Chlorine-36
Argon-36
300 thousand yrs
Beryllium-10
Boron-10
160 thousand yrs
Dysprosium-153
Terbium-153
100 thousand yrs
Carbon-14
Nitrogen-14
5730 years
Is Radioactive Decay Valid?
• Travel in a time capsule to see if the physics of
radiometric dating still apply.
• The gamma ray frequencies and intensities produced by
radioactive elements in supernova remnants change in
the same predictable way as they do here on the Earth.
• Example
– supernova SN1987A that is 169,000 light years away
in a satellite galaxy of the Milky Way. The predictions
for the decay rates have turned out to be correct for
all of the radioactive elements we have detected in
that remnant. Since the SN1987A is 169,000 light
years away, that tells us the decay rates were not
different 169,000 years ago. We find similar results
for supernova remnants even further away
The Appearance of Age
• Both parent and daughter elements in each
radioactive chain were created at the
beginning, probably in “equilibrium” amounts.
The amount of originally created radiogenic
end-product in each chain is uncertain; it is
likely however, that homologous amounts
were created in all such minerals so that all
such elements would, when created, give an
“ appearance” of the same degree of maturity
or of age.
The Appearance of Age
• In 10,000 years since creation, the actual
starlight that has had enough time to reach
us comes form only a tiny proportion of our
neighbors. This means that every event
witnessed at a distance by Hubbell space
telescope and other astronomical
instruments, including the explosive
disintegration of stars and the gravitational
effects of black holes, is fictitious. None of
these things happened-they were all
constructed, artificially, in the trillions of
photons assembled by the Creator to give his
cosmos an appearance of age
The Character of God
• Schemer?
• A trickster?
• A charlatan?
• A God who intentionally plants misleading
clues beneath our feet and in the heavens
themselves.
• This is all to lead astray anyone who uses
their God given ability to reason
• What effect does the views of Young Earth
Creationist’s have on promoting Christian
morality and ethics in society?
Reason and Faith
• “It is a disgraceful and dangerous thing for
an unbeliever to hear a Christian
presumably giving the meaning of
scripture and talking nonsense on these
topics.”
• “Many non-Christians are well versed in
natural knowledge so they can detect vast
ignorance in such a Christian and laugh
him to scorn.”
– St. Augustine 387 AD.
Reason and Faith
I am not astonished that infidelity prevails to
a great extent among the inhabitants of
the earth, for the religious teachers of the
people advance many ideas and notions
for truth which are in opposition to and
contradict facts demonstrated by science,
and which are generally understood.
(Brigham Young Journal of discourses 1856,)
Is it important to know the story of
the creation?
• If the Christian religion (indeed any
religion) is to be believable and have
intellectual integrity enough to command
even the attention, let alone the assent, of
thoughtful people in the beginning of the
next millennium they must begin to
acknowledge the ideas of Darwin and the
truths of science.
– Author Peacocke 1999
Why is it important to understand the
validity of Radioisotope dating?
• The Earth is very old.
• Life on earth is at least 500 million years old.
• Modern looking humans have been on the earth
for at least 100,000 years.
• The Americas have been continuously populated
for over 10,000 years.