Dating Ancient Limestone in Ireland

Dating Ancient Limestone in Ireland

In County Clare, Ireland, one of the main sight-seeing destinations is the Burren, a stretch of terrain often described as “lunar” in appearance. The karst landscape features expansive limestone pavements crisscrossed by cracks known as “grikes” (as though raked by a giant attempting to farm) and solemn portal tombs such as the Neolithic Poulnabrone Dolmen.

When I visited the Burren, I sensed a sort of ancientness hanging over the region and felt humbled by the history saturating the very stones I stood on. Information plaques posted near the Poulnabrone Dolmen told me this obscure burial site is possibly older than both Stonehenge and the Pyramids of Egypt. But oldest by far is the limestone itself, coming in at an impressive 340 million years old.

Scientists determine the date for the Burren and its artifacts using a technique called radiometric dating. And yet the reliability of this technique is a source of debate among Christian creationists. While old-earth proponents accept radiometric dating as valid, young-earth supporters doubt radiometric dating’s validity, often citing examples of wildly inaccurate results in support of their skepticism. I once had a fellow believer tell me these methods had been proven unreliable by a scientist who got a reading of thousands of years when he tested radiometric dating on a live snail.

The Institute of Creation Research even published a collection of papers documenting eight years work on the Radioisotopes and the Age of The Earth (RATE) project. Their conclusions challenged radiometric dating results and supported the young-earth view. (See here for a review of the study by Randy Isaac, executive director of the American Scientific Affiliation.)

RTB astronomer Hugh Ross addresses challenges to radiometric dating in his book A Matter of Days. He writes,

Just as thermometers, barometers, and radar all have specific applications and limits, so too do the more than 40 different radiometric decay dating methods….

Supposed ‘evidence’ against the reliability of radiometric dating focuses on the method’s ‘flaws’ or inaccuracies when applied outside its limitations….

When used outside of its intended purposes or limitations, any dating technique can produce incorrect and unreliable results. When used within its intended purposes and limitations, radiometric dating can and does serve as a reliable and trustworthy tool…

Hugh lists three requirements for obtaining accurate radiometric dating results.

  1. Proximity of the actual date to the (measureable) half-life of the radiometric chronometer (for example, carbon-14 dating is most reliable for organic material between 900–35,000 years old)
  2. Adequate sample size
  3. Adequate sample purity
With these three requirements in mind, it seems misuse of the technique renders tests on things like live snails irrelevant.

Thinking back on my experience at the Burren reminds me of God’s challenge to Job: “Where were you when I laid the earth’s foundation? Tell me, if you understand.” The Burren’s human history, though fascinating and ancient, pales in comparison to the awesome power and creative abilities of the eternal Designer of the very old universe.

— Maureen

Resources: Check out these RTB resources for more information on radiometric dating.