Claim CD011.4:
A freshly killed seal was carbon-14 dated at 1300 years old.
Source:
Response:
- This claim derives from Wakefield (1971):
Radiocarbon analysis of specimens obtained from mummified seals in
southern Victoria Land has yielded ages ranging from 615 to 4,600
years. However, Antarctica sea water has significantly lower
carbon-14 activity than that accepted as the world
standard. Therefore, radiocarbon dating of marine organisms yields
apparent ages that are older than true ages, but by an unknown and
possibly variable amount. Therefore, the several radiocarbon ages
determined for the mummified seal carcasses cannot be accepted as
correct. For example, the apparent radiocarbon age of the Lake Bonney
seal known to have been dead no more than a few weeks was determined
to be 615 +/- 100 years. A seal freshly killed at McMurdo had an
apparent age of 1,300 years.
This is the well-known reservoir effect that occurs also with
mollusks and other animals that live in the
water. It
happens when "old" carbon is introduced into the water. In the above
case of the seal, old carbon dioxide is present within deep ocean
bottom water that has been circulating through the ocean for thousands
of years before upwelling along the Antarctic coast.
The seals feed off of animals that live in a nutrient-rich upwelling
zone. The water that is upwelling has been traveling along the bottom
for a few thousand years before surfacing. The carbon dioxide in it
came from the atmosphere before the water sank. Thus, the carbon in
the sea water is a couple of thousand years "old" from when it was in
the atmosphere, and its radiocarbon content reflects this time. Plants
incorporate this "old" carbon in them as they grow. Animals eat the
plants; seals eat the animals, and the "old" carbon from the bottom
waters is passed through the food chain. As a result, the radiocarbon
content reflects a mixture of old radiocarbon, which is thousands of
years old, and contemporaneous radiocarbon from the atmosphere. The
result is an apparent age that differs from the true age of the seal.
The reservoir effect is well known by scientists, who work hard to
understand the limitations of their tools. It is explained, for
example, in Faure (1986) and Higham (n.d.). Contrary to creationist
propaganda, limitations of a tool do not invalidate the tool.
References:
- Faure, G., 1986. Principles of Isotope Geology, 2nd ed. New York:
Wiley.
- Higham, Thomas, n.d. Corrections to radiocarbon dates.
http://www.c14dating.com/corr.html
- Wakefield, Dort, Jr., 1971. Mummified seals of southern
Victoria Land. Antarctic Journal 6(5): 210-211.
Further Reading:
Aitken, M. J., 1990. Science-based Dating in Archaeology.
Longman, England.
Bowman, Sheridan, 1990. Radiocarbon Dating. Berkeley: University of
California Press.
Taylor, R. E., 1987. Radiocarbon Dating. An archaeological
perspective. Orlando, USA: Academic Press.
created 2003-6-1, modified 2004-7-8
