Making Sense of the Patterns This three-part series will help you properly understand radiometric dating, the assumptions that lead to inaccurate dates, and the clues about what really happened in the past. Most people think that radioactive dating has proven the earth is billions of years old.
Yet this view is based on a misunderstanding of how radiometric dating works. Part 1 in the previous issue explained how scientists observe unstable atoms changing into stable atoms in the present. Part 2 explains how scientists run into problems when they make assumptions about what happened in the unobserved past.
When we look at sand in an hourglass, we can estimate how much time has passed based on the amount of sand that has fallen to the bottom.
They also measure the sand grains in the bottom bowl the daughter isotope, such as lead or argon, respectively. Based on these observations and the known rate of radioactive decay, they estimate the time it has taken for the daughter isotope to accumulate in the rock. Conditions at Time Zero No geologists were present when most rocks formed, so they cannot test whether the original rocks already contained daughter isotopes alongside their parent radioisotopes.
For example, with regard to the volcanic lavas that erupted, flowed, and cooled to form rocks in the unobserved past, evolutionary geologists simply assume that none of the daughter argon atoms was in the lava rocks.
Yet lava flows that have occurred in the present have been tested soon after they erupted, and they invariably contained much more argon than expected. So it is logical to conclude that if recent lava flows of known age yield incorrect old potassium-argon ages due to the extra argon that they inherited from the erupting volcanoes, then ancient lava flows of unknown ages could likewise have inherited extra argon and yield excessively old ages. We find places on the North Rim where volcanoes erupted after the Canyon was formed, sending lavas cascading over the walls and down into the Canyon.
These basalts yield ages of up to 1 million years based on the amounts of potassium and argon isotopes in the rocks.
But when we date the rocks using the rubidium and strontium isotopes, we get an age of 1. This is the same age that we get for the basalt layers deep below the walls of the eastern Grand Canyon. This source already had both rubidium and strontium. To make matters even worse for the claimed reliability of these radiometric dating methods, these same basalts that flowed from the top of the Canyon yield a samarium-neodymium age of about million years, 5 and a uranium-lead age of about 2.
No Contamination The problems with contamination, as with inheritance, are already well-documented in the textbooks on radioactive dating of rocks. Similarly, as molten lava rises through a conduit from deep inside the earth to be erupted through a volcano, pieces of the conduit wallrocks and their isotopes can mix into the lava and contaminate it.
Because of such contamination, the less than year-old lava flows at Mt. Constant Decay Rate Physicists have carefully measured the radioactive decay rates of parent radioisotopes in laboratories over the last or so years and have found them to be essentially constant within the measurement error margins.
Furthermore, they have not been able to significantly change these decay rates by heat, pressure, or electrical and magnetic fields.
So geologists have assumed these radioactive decay rates have been constant for billions of years. However, this is an enormous extrapolation of seven orders of magnitude back through immense spans of unobserved time without any concrete proof that such an extrapolation is credible. New evidence, however, has recently been discovered that can only be explained by the radioactive decay rates not having been constant in the past. Yet the same uranium decay also produced abundant helium, but only 6, years worth of that helium was found to have leaked out of the tiny crystals.
This means that the uranium must have decayed very rapidly over the same 6, years that the helium was leaking. As this article has illustrated, rocks may have inherited parent and daughter isotopes from their sources, or they may have been contaminated when they moved through other rocks to their current locations. Or inflowing water may have mixed isotopes into the rocks.
In addition, the radioactive decay rates have not been constant.