Old Earth theories propose that the Earth has existed for billions of years. These theories developed in connection with the theory of evolution, which would could not have possibly occurred in the thousands of years that people had previously estimated the age of the Earth to be.
Old Earth theories struggle to explain youthful characteristics of the earth, such as the massive fresh water Great Lakes. Over long periods of time fresh water reservoirs would inevitably dissipate. Theories of Ice Ages developed as a way to explain fresh water reservoirs. Underground wells provide a similar challenge for Old Earth advocates.
Flooding is another challenge for Old Earth advocates, as it would wipe out any evolutionary path, particularly among mammals. The likelihood of a massive flood increases with the period of time, and an older Earth means more disruptive flooding.
The principle basis for Old Earth is radiometric dating, but it is a logical tautology to assume that radioactive decay rates have always been constant, even at higher energy levels. Such assumption is identical to assuming that the Earth is old, and hence that argument is circular.
The discipline of uniformitarianism is also a basis for assuming an old Earth. Extrapolating the rate of geologic processes backwards in time yields an Earth substantially older than the Biblical 6,000 years. Uniformitarianism is also based on assumptions, however; namely, that all geologic processes were acting at the same or similar rates for the whole history of the Earth.
Contradiction in Old Earth Theory
The fundamental contradiction in the belief in an Old Earth is this:
- physical laws, such as rates of decay, must have been different at higher energies and times closer to the origin of the universe
- yet physical rates, such as rates of decay, must somehow have been constant since the origin of the universe, in order to use extrapolation to date it
Physical origin of the Earth
Those who accept an old Earth generally believe that natural processes formed the Earth and solar system over a long period of time. This is as opposed to the Young-Earth creationist belief in an essentially instantaneous creation.