quote:
Living Seals were carbon-dated as having died 1400 years ago! The shell of a living clam was carbon-dated as having died thousands of years ago!
It was actually a snail, not a clam. These are from reports of tests from the early 1960's to early 1970's, and were publicized by the infamous Kent Hovind. Since then, the reservoir effect was discovered. The reservoir effect is where old carbonate/bicarbonate salts are in a water supply, which have a diminished concentration of 14C due to their age, thus diluting the 14C ratio in the water body and, when that carbon works its way into the bodies of the creatures living in the water, gives a false, old age.
For example, the snails lived in what is called a limestone catchment, a lake fed by underground springs in which the ground water traveled through limestone (calcium carbonate ) formations. The carbonate in the limestone, being very old, no longer had any 14C. When the grounwater travels through the limestone beds, some of the calcium carbonate (with depleted 14C) dissolves into the water, and then into the lake. The carbonate is taken up by the snails, and used to make their shell material. Since the 14C concentration was diluted, radiometric dating of its shell gave a false, old age.
In the case of the seals, which lived around Antartica, a deep ocean current upwelling exists, where a current which has traveled deep along the ocean floor for thousands of years upwells back to the surface. The current contains the dissolved CO2 and carbonates from when the current first descended from the surface to the depths thousands of years ago. During the years on the sea floor, the C14 in the carbonate in the deep current decayed, so when the current upwelled, the 14C concentration in the bicarbonate was again depleted. This bicarbonate was taken up by plankton, and then worked its way up the food chain, ultimately to the seals. The carbonate in their bodily tissues, having a depleted 14C conc., gave an artificially old age.
More information on the reservoir effect is here:
Corrections to radiocarbon dates.
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