Monday, October 1, 2012

So How Old Are the Rocks, Anyway?

The method used by geologists and others to date the age of the Earth is to date the age of the rocks found on the Earth. Radiometric Dating is the official name of the process, and to most people, especially when listening to scientists describe this process, it sounds like a trustworthy clock in order to accurately measure the age of Earth’s materials. In addition, this method is one of the linchpins of evolutionary education today, and presents the Earth as being billions of years old.

First of all, the method is based on a simple fact about atoms—if it has too many neutrons in its nucleus, it is unstable and will change into a stable form. Therefore, to date a sample, scientist calculate how much time would be required for the unstable atoms in the sample to change into a stable form.

Left: Carbon-12, a stable atom; Center: Carbon-13, a stable atom; Right: Carbon-14, an unstable atom because it has too many neutrons [yellow=Protons; blue=Neutrons; green=Electrons

For example, most carbon atoms are stable (unchanging) because they have only six or seven neutrons in their nuclei, but some carbon atoms (C-14) have too many neutrons and are unstable. That is, the neutrons in Carbon-14 are too large and will break down over a known period of time—these isotopes are radioactive and to achieve stability, the atom must make adjustments, particularly in its nucleus. In doing so, they eject particles, primarily neutrons and protons, which are the moving particles measured by Geiger counters. This is done to achieve stability; however, the end result is a different chemical element (not carbon) because the atom now has a different number of protons and electrons.

Thus, this process of changing one element (the parent isotope) into another element (the daughter isotope) in the process known as radioactive decay (the parent isotopes that decay are called radioisotopes, though there is no real decay, just a change from one atom to another). As an example, the parent uraniunm-238 changes into the daughter lead-206; uranium-235 changes to lead-207; potassium-40 changes to argon-40; rubidium-87 changes to strontium-87; and samarium-147 changes to neodymium-143, which are the five parent isotopes that geologists use to date rocks. Carbon-14 is not used (radiocarbon) because most rocks do not contain carbon.

Unstable atoms, such as uranium (U), eventually change into stable atoms, such as lead (Pb). The original version is called a parent atom (or isotope), and the new version is called a daughter atom

Nor can geologists use any old rock for dating. They must find rocks that have the isotopes listed above, even if these isotopes are present in only minute amounts. Typically, this is a rock body that has formed from the cooling of molten rock material (magma), like granite and basalts. Scientists then  measure the amount of the parent and daughter isotopes in a sample of the rock. Since laboratories can do this with accuracy and precision, few people quarrel with the resulting chemical analyses.

However, the system by which scientists interpret the information is based upon three all-important, but unprovable assumptions: 1) the original number of unstable atoms can be known—that is, scientists assume how many  unstable (parent) atoms existed at the beginning (formation of the rock) based on how many parent and daughter atoms are left today; 2) The rate of change was constant—that is, scientists assume that radioactive atoms have changed at the same rate throughout time, ignoring the impact of Creation or changes during Noah’s Flood, or the division of the Earth, etc.; and 3) The daughter atoms were all produced by radioactive decay—that is, scientists assume that no outside forces, such as flowing groundwater, contaminated the sample.

Now, since the rocks are supposed to be millions, or even billions, of years old, there is no possible way anyone today can determine any of these three assumptions to have existed as the measurement requires. As an example, not one was around millions of years ago to see what the rock contained at the beginning when it was formed, nor was anyone around during the intervening millions of years to see what might have happened to the rock during its lifetime, nor was anyone around during the Creation, Flood, or the dividing of the Earth, to see how these events interacted with the rock sample in question.

When Mt. Ngauruhoe in New Zealand erupted in 1954, new rocks were formed when the ejected magma cooled. These brand new rocks were dated by radiometric Dating and yielded a 3.5 million-year-old “age”

Obviously, then, if these clocks are based on faulty assumptions and yield unreliable results, then scientists should not trust or promote the claimed radioactive “ages.” Take for an example:

• Scientists do not know how many daughter atoms were present when most rocks first formed, so when they test rocks produced by lava flows in recent years, their bad assumptions yield inaccurate and old ages.
• A rock formed at Mount St. Helens in 1986 yielded a radiometric age of 350,000 years
• A rock formed by lava flows at New Zealand’s Mt. Ngauruhoe in 1954 yielded a radiometric age of 3.5 million years
• A rock at the top of Grand Canyon formed by a recent volcanic eruption yielded the same age as volcanic rocks deep below the canyon wall—1.143 billion years
• Mt.Etna in Sicily erupted in 122 B.C., but those rocks were recently dated to being 170,000 to 330,000 years old
• Mt. Etna 1972 basalt eruption formed rocks that were dated to 210,000 to 490,000 years old
• Kilauea Iki basalt in Hawaii formed 1959 but dated to 1.7 to 15.3 million years old
• Precambrian Cardenas Basalt in the Uinkaret Plateau dates younger (1 billion years old) than the Paleozoic  lava flows over the top of the sediments which date to 2.6 billion years
• Scientists  do not know how quickly radioactive atoms decayed in the past. So they assume a constant rate, but when they tested zircon crystals from a borehole in New Mexico, they found two very different dates, depending on what measurement they used…measuring the uranium these crystals yielded an age of 1.5 billion years—but measuring the amount of helium that leaked out as a result of the decay yielded an age of 6,000 years
• Scientis do not know how much the rocks have been contaminated so they usually assume no contamination, yet contamination of lava flows at Mt. Ngauruhoe, known to be less than 50 years old yielded three different ages—133 million years, 197 million years and 3.908 billion years

(See the next post, “So How Old Are the Rocks, Anyway? – Part II – The Assumptions,” to see how badly scientific assumptions mar the accuracy of what is believed to be an accurate way to measure the age of the Earth)

1 comment:

  1. Excellent posts about the age of the earth, carbon dating, etc. Clears up a lot of questions I have had over the years about why dates of carbon dating do not line up with scripture. Thank you Del.