Usually I don’t like to mix geological arguments for an old earth with evidence for the theory of evolution as anti-evolutionists have a tendency to conflate the two as both part of some grand evolutionary cabal of evil instead of as two very separate disciplines that happen to independently support each other. However, in this series I’ll make an exception. This is a continuation of a previous thread, Evolution Happens, and is meant to gradually extend the concepts laid down therein. Previously we’ve seen how evolution is a reality, and by that I mean that the mechanisms of evolution (random mutations acted upon by selective pressures) have been observed to result in beneficial mutations that allow living things to do something they couldn’t do before. We also saw that there is no actual mechanism that would prohibit how far these beneficial mutations could change populations if given enough time, this thread exists to examine the current evidence for there being “enough time”.
(Note: The topic of this thread is concerned with the age of the earth, not the mechanisms of evolution, which can be discussed in Evolution Happens, or the applications of that mechanism onto large chunks of time, which will be the subject of an upcoming thread. As always, the purpose of this is not to convince individuals on a personal level but to provide an overview of how standard science explains the observable. If you have your own opinions on this subject that is your business, but I would that you would ask yourself why anyone else should care about your opinions if your theory can’t explain as much, or more, than the standard theories of biology and geology do.)
Current geologists date things using two methods; relative dating, which looks at stratigraphy, and absolute dating, which looks at stable radioactive decay rates to date things with a higher degree of accuracy. The former has been used as far back as the 11th century to deduce that the earth is older than YE interpretations can allow, while the later is a comparatively new field.
To understand absolute dating methods you need to understand some of the basic properties of matter. All matter is composed of atoms, which are in turn composed of a nucleus made of positively charged particles (protons) and particles with a neutral charge (neutrons) orbited by a cloud of electrons. Here’s an example. The number of protons determines what element it is. In our example above there are two protons and two neutrons, so we can flip over to our periodic table and look for an element with an atomic number of 2 (atomic number = number of protons) and in doing so we can see that this is a helium atom.
Each element can have a given number of isotopes, these are atoms that have the same number of protons but a different number of neutrons. As an example, here’s an isotope of helium. Notice that while the number of neutrons has changed this is still a helium atom because it still has two protons. This will become important later.
Atoms that are radioactive are unstable, so they throw off particles until they reach a more stable state. As the nucleus loses neutrons the atom can become a different isotope, as it loses protons the atom actually becomes a different element. We call this loss of particles “radioactive decay”, the original element is called the “parent”, while the new more stable form is called the “daughter”.
I really can’t stress enough that this is a very simplistic explanation of a very complicated process. If you want to get into exactly how or precisely why atoms and their particles behave this way you start getting into strong and weak nuclear forces and everybody starts to get headaches. That being said, the average decay rate is governed by those forces and, as such, is known. There’s no mechanism we know of that can actually alter these decay rates significantly. . .unless you drop a particularly unstable isotope into the center of, say, a very large star and strip off all it’s electrons. However, the decay rate for every isotope of every atom is unique, which means that if all of this were based on assumptions we wouldn’t expect different radiometric dating methods to reach the same results, which they consistently do.
Additionally, if radiometric dating isn’t reliable we certainly wouldn’t expect for radiometric dates to line up with non-radiometric dates derived from things like tree rings and varves but, again, they consistently do.
Further reading material on radiometric dating:
- Radiometric Dating: A Christian Perspective
- Age Correlations and an Old Earth
- Why Radiocarbon Dating Works – Lake Suigetsu
Ultimately, however, the strength of any theory depends on it’s ability to explain what we see. In this respect standard geology outstrips anything YE geology has been able to come up with so we shouldn’t at all be surprised that non-YEC’s reject YE geology wholesale. If YE Creationists want to change this they need to come up with YE geological models that explain formations and findings such as the law of faunal succession and radiometric decay rates as well or better than standard geology models.
So far we’ve seen that the basic mechanism of evolution does work, and that there was plenty of time for it to work in, which brings us to the essential point of the third part in this series; if evolution happens and if there was enough time for it to “happen in” why couldn’t the theory of evolution be true?
Itinerant Lurker 