evolved yet?
A Young Evolutionist
Age of the Earth
Methods scientists use to give an age for the earth.
Ways to find the age for the earth:
We can try to find the oldest rocks on the earth. While this doesn't guarantee an absolute age (for the original rocks aren't be available), it can at least give a lower limit for the age of the earth.
The oldest rocks exposed on the surface of the earth are 3.5 to 3.8 billion years in age. Consider the various dating methods applied to the Greenland Amitsoq Gneiss:
Rb-Sr isochron 3.70 +- 0.14 billion years
Pb-Pb isochron 3.80 +- 0.12 billion years
U-Pb discordia 3.65 +- 0.05 billion years
Th-Pb discordia 3.65 +- 0.08 billion years
Lu-Hf isochron 3.55 +- 0.22 billion years
Note that all of the methods agree (3.68-3.70 is within all of their ranges of error). Isochron and discordia methods also have an internal check which identifies undateable samples. Similar formations which give similar ages can be found as well in Everywhere. This date therefore gives some confidence.
If Danmac wishes to object to these dates, he will have to explain why a 10,000-year-old rock was "created" so that five independent dating methods would all yield the same fictitious age.
We can try to date other objects in the solar system. Both sides of the debate believe that other objects in the solar system formed at about the same time as the earth, and therefore an age for one of those objects is an age for the earth.
The moon is not as geologically active (dating should be more reliable, as rocks have less complex "histories"). Again, the original rocks need not be available, so the age will only be a lower limit; the moon must be at least as old as the oldest rocks we've found on it.
Lunar basalts were collected by six different Apollo expeditions, from six different sites. These samples all give ages ranging from 3.16 to 3.96 billion years, by both Rb-Sr isochron and Ar-Ar dating methods. When both methods are applied to one sample, the results agree to within 3%.
Meteorites are not geologically active at all; there is good reason to expect that most are undisturbed since their formation with the rest of the solar system.
Chondritic meteorites consistently give an Rb-Sr isochron age of 4.49 +- 0.07 billion years. Achondritic meteorites consistently give an Rb-Sr isochron age of 4.36 +- 0.11 billion years. A combined method using samples of minerals from many different meteorites gives an Rb-Sr isochron age of 4.46 +- 0.08 billion years.
I doubt Danmac has a convincing explanation for how young, "independently created" objects from all over the solar system could have their lead contents form an isochron. I wonder how he will account for the fact that the resulting age matches other dating methods' results for the solar system.
Your Turn
Methods scientists use to give an age for the earth.
Ways to find the age for the earth:
We can try to find the oldest rocks on the earth. While this doesn't guarantee an absolute age (for the original rocks aren't be available), it can at least give a lower limit for the age of the earth.
The oldest rocks exposed on the surface of the earth are 3.5 to 3.8 billion years in age. Consider the various dating methods applied to the Greenland Amitsoq Gneiss:
Rb-Sr isochron 3.70 +- 0.14 billion years
Pb-Pb isochron 3.80 +- 0.12 billion years
U-Pb discordia 3.65 +- 0.05 billion years
Th-Pb discordia 3.65 +- 0.08 billion years
Lu-Hf isochron 3.55 +- 0.22 billion years
Note that all of the methods agree (3.68-3.70 is within all of their ranges of error). Isochron and discordia methods also have an internal check which identifies undateable samples. Similar formations which give similar ages can be found as well in Everywhere. This date therefore gives some confidence.
If Danmac wishes to object to these dates, he will have to explain why a 10,000-year-old rock was "created" so that five independent dating methods would all yield the same fictitious age.
We can try to date other objects in the solar system. Both sides of the debate believe that other objects in the solar system formed at about the same time as the earth, and therefore an age for one of those objects is an age for the earth.
The moon is not as geologically active (dating should be more reliable, as rocks have less complex "histories"). Again, the original rocks need not be available, so the age will only be a lower limit; the moon must be at least as old as the oldest rocks we've found on it.
Lunar basalts were collected by six different Apollo expeditions, from six different sites. These samples all give ages ranging from 3.16 to 3.96 billion years, by both Rb-Sr isochron and Ar-Ar dating methods. When both methods are applied to one sample, the results agree to within 3%.
Meteorites are not geologically active at all; there is good reason to expect that most are undisturbed since their formation with the rest of the solar system.
Chondritic meteorites consistently give an Rb-Sr isochron age of 4.49 +- 0.07 billion years. Achondritic meteorites consistently give an Rb-Sr isochron age of 4.36 +- 0.11 billion years. A combined method using samples of minerals from many different meteorites gives an Rb-Sr isochron age of 4.46 +- 0.08 billion years.
I doubt Danmac has a convincing explanation for how young, "independently created" objects from all over the solar system could have their lead contents form an isochron. I wonder how he will account for the fact that the resulting age matches other dating methods' results for the solar system.
Your Turn
