Dr. Hovind (R4): It is very difficult or impossible to prove that a given sample has not been contaminated. Parent or daughter products could have leached in or out of the sample.

R4. In the case of carbon-14 dating, the daughter product is ordinary nitrogen and plays no role in the dating process. We are only interested in the amount of C-14 present in the sample. Since the C-14 is an integral part of the carbon structure of a sample, such as cellulose, it isn't going to do much migrating. If it did there wouldn't be any sample left! Residues which do migrate can usually be washed out with various chemicals.

A sample, of course, can be contaminated if organic material, rich in fresh atmospheric C-14, thoroughly penetrates it. Such contamination will make the sample appear younger than its true age. Thus, creationists are barking up the wrong tree on the contamination issue!

Laboratories, of course, do have techniques for identifying contamination and correcting for it. There are various methods of cleaning the material, and the activity of each rinse can be measured. Lab contamination can be checked for by running blanks. A careful choice of samples can often minimize or check contamination. Dating various portions of a sample is another kind of check on contamination.

Often there are cross-checks. Samples from top to bottom of a peat bog gave reasonable time intervals (Science, vol.200, p.11). The calibrated C-14 method confirmed Egyptian records, and most of the Aegean dates which were cross-dated with Egyptian dates were confirmed (American Scientist, May-June 1982). The marvelous agreement with tree-ring data, after correction for variations in the earth's magnetic field, has already been mentioned.

Carbon-14 dating thus presents a deadly challenge to young-earth creationists. If an old date is reasonably accurate, they're out of business; if an old date is bad, then they are still out of business because the true date is almost certainly older still. On the average, the great majority of bad dates would be too young. It hardly seems fair, but that's the way it is. With that in mind, let's look at a few carbon-14 dates.

Egyptian barley samples were found which dated to 17,000-18,300 years old (Science, April 7, 1978). On page 1346 the author explains some of the care that goes into such dates.

A wooden walkway buried in a peat bog in England dated to about 4000 BC (Scientific American, August 1990, p.30). Odd, that Noah's flood neither destroyed it nor deposited thick sediments on top of it! Jennifer Hillam of the University of Sheffield and Mike Baillie of Queen's University of Belfast and their colleagues were actually able to date the walkway by tree-ring dating. The road, known as the Sweet Track, was built from trees felled in the winter of 3807-3806 BC. Pretty close agreement, huh?

Stonehenge, as dated by carbon-14, was built over a period from 1900 BC to 1500 BC -- long before the Druids came to England. Astronomer Gerald Hawkins found, after careful computer calculations, that the arrangement of the stones at Stonehenge are aligned with key positions of the sun and moon as they were almost 4000 years ago. (Weber, 1982, p.29). Thus, we have another remarkable confirmation of the C-14 method.

When did the volcano that destroyed Thera (and probably the Minoan culture as well) explode? Radiocarbon dating of seeds and wood buried in the ash, done by scientists at the University of Pennsylvania, pointed to no later than 1600 BC. Being that this was one of the biggest volcanic eruptions in recorded history, it almost certainly caused worldwide cooling which would, in turn, affect tree growth. Sure enough, the growth rings among oaks buried in Ireland's bogs show the effect of unusual cooling from 1628-1618 BC. Nor was that just an effect of local weather conditions. The bristlecone pines in the White Mountains of California show the same thing. A third estimate came from studies in Greenland. "In 1987 Danish geologists examining signs of volcanic acidity in the Greenland ice sheet concluded that the Thera volcano erupted in 1645 B.C., give or take 20 years. (Biblical Archaeology Review, Jan/Feb 1991, p.48). Thus, we have a remarkable agreement between three different methods, all within two or three percentage points of each other!

Trees buried by the last advance of glacial ice at Two Creeks, Wisconsin were dated at 11,850 years. (Strahler, 1987, p.251). Between those trees, which are buried in Valders red till, and an earlier, deeper layer of till, the Woodfordian gray till, lay the remains of a forest bed! What is a forest, including developed soil and rooted stumps, doing between two advances of ice? That could be an interesting question for someone who believes in only one "ice age." In 1878 Baron Gerard de Geer, a Swedish geologist, made a careful study of the annual varves left in European glacial lakes. By careful counting and cross-checking he was able to determine that the oldest glacial lakes, which would have formed at the start of the retreat of the ice, were 12,000 years old. Thus, we have a rough check between varves in glacial lakes and radiocarbon dating.

"Richard Foster Flint, a professor of geology at Yale University and an expert on the Pleistocene epoch, was among the first to apply radiocarbon dating to glacial events. Collecting wood, bones and other organic material that had been covered over by the Laurentide Ice Sheet as it plowed across eastern and central North America, Flint collaborated with geophysicist Myer Rubin to demonstrate in 1955 that in most places the ice sheet achieved its greatest advance about 18,000 years ago, began to withdraw shortly thereafter and then hastened its retreat about 10,000 years ago." (Chorlton, 1984, p.120)

Ancient cave art, at cueva de los caballos, near Castellon, Spain has been dated at about 6000 BC. (The Times Atlas of World History [1978]).

On the wall of Gargas Cave in the French Pyrenees are the outlined hands of Ice Age artists which date to at least 12,000 years. Such cave art, in various places in Europe, was at its height around 20,000 years ago, and some examples probably go back 30,000 years!