Radiometric dating: Assumption One Debunked

Last year I started studying radiometric dating to see if the grand old ages for the earth, as presented by the evolutionary establishment do indeed stack up. This is something every thinking person on the planet should do. Below is a snippet of what I found out and will be in an essay published on the website later this year.

Modern radioisotope dating methods are like watching sand slide through an hour glass and working backwards to find the initial starting time. To trust an hour glass that is running with sand at the bottom we have to know if it was empty when we started, whether the flow has been consistent and unclogged, and whether no sand was added or subtracted from the pile at the bottom before we observed it.

The first of those three assumptions, in science-speak, goes something like this:

When the rock forms and hardens there should only be parent radioactive atoms in the rock and no daughter radiogenic atoms derived by radioactive decay.

If this assumption is violated, then the technique fails and all dates produced are false. If daughter atoms were present then the assumed age would be much older than the real age. Lets look at this assumption in detail to see if it stacks up by looking at the ages given for rocks that have a known historical age.

The potassium-argon (K–Ar) dating method is often used to date volcanic rocks. In using this method, it is always assumed that there was no daughter radiogenic argon in rocks when they formed. The K–Ar method works on the assumption that the radioactive decay ‘clock’ begins to ‘tick’ after the lava cooled and solidified as the argon from radioactive decay was unable to escape and started to accumulate.

For volcanic rocks which cool from molten lava, this would seem to be a reasonable assumption. Because argon is a gas, it should escape to the atmosphere due to the intense heat of the lava. It also assumes that no argon from radioactive decay was present initially. We can test these assumptions by studying modern lava flows of a known historic date.

In 1996 geologist Andrew Snelling investigated lava flows from Mt Ngauruhoe in New Zealand (Mt Doom in the Lord of the Rings movies!). Eleven samples were collected from five recent lava flows that occurred in 1949, 1954 and 1975.

The samples were sent progressively in batches to Geochron Laboratories in Boston for whole-rock potassium-argon (K–Ar) dating. Geochron is a respected commercial laboratory, with the K–Ar lab manager having a Ph.D. in K–Ar dating. The ‘dates’ obtained from the K–Ar analyses ranged from 0.27 to 3.5 (± 0.2) million years for rocks which were observed to have cooled from lava 25–50 years ago. The lab manager kindly re-checked his equipment and re-ran several of the samples, producing similar results. This ruled out a systematic lab error and confirmed that the low results were real.

Clearly, the argon content varies greatly within these rocks. Some geochronologists would say <0.27 million years is actually the correct ‘date’, but how would they know that 3.5 million years was not in fact the correct ‘age’ if they did not already know the lava flows were recent?

Because these rocks are known to be less than 50 years old, the K–Ar dates in the hundreds of thousands of years must be due to excess argon the rock inherited from the magma deep in the earth when the rock first formed. When the lava cooled the rocks contained higher than zero concentrations of normal radiogenic argon, which is indistinguishable from daughter radiogenic argon derived by radioactive decay of its parent potassium.

Some critics have argued that the magma must have picked up chunks of old rock as it moved through the Earth. They claim, without evidence, that these pieces of old rock, xenoliths, contaminated the sample and gave the very old age. Dr Austin anticipated this line of criticism and was particularly careful to identify xenoliths and ensure none were included in the sample. Other critics suggested feldspar crystal size gave wrong ages. This criticism was also anticipated, and proved incorrect as the old ages came from multiple crystals.

In another obvious example of dating error, rock samples from a lava dome within the Mount St Helens in the USA were dated using the K-Ar method. Whole-rock samples gave ages from 1.0 to 3.5 million years. However, the lava dome only formed after Mount St Helens exploded in 1980 and the samples were just 10 years old at the time the samples were tested. Similar errors have been compiled for historically known lava flows in Hawaii, Mt Etna in Italy, Mt Lassen in California and the Sunset crater in Arizona.

These examples of dating error clearly violate assumption number one of radioactive dating. The bottom of the geological hourglass was not empty of radioactive “sand” when it was flipped. Therefore, all potassium-argon tests and dates for the earth’s basement rocks are invalid. If the method fails on rocks when we have an independent eye-witness account, then why should we trust it on other rocks where there are no independent historical cross-checks?

In regards to rocks of unknown history but the same origin and location, radioisotope dating often gives us vastly inconsistent ages. This is another clue that daughter atoms were present when the rocks were formed. One study took samples of rock from the Grand Canyon and tested their ages with respected laboratories. Seven samples from one rock formation, which should all be the same age because they belong to the same metamorphosed basalt lava flow, gave ages ranging from 1,060 million to 2,574 million years. This includes two samples only 0.84 meters apart that yielded K-Ar model ages of 1,205 million years and 2,574 million years respectively. Is it any wonder that preconceived assumptions about the age of the earth play such a huge role in the dates that are accepted and those that are rejected?

Kevin Davis


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