In principle, any material of plant or animal origin, including textiles, wood, bones and leather, can be dated by its content of carbon 14, a radioactive form of carbon in the environment that is incorporated by all living things.
Scientists at the Lamont-Doherty Geological Laboratory of Columbia University at Palisades, N.
Y., reported today in the British journal Nature that some estimates of age based on carbon analyses were wrong by as much as 3,500 years.
Permafrost—soil that remains frozen year-round—lies underneath the moss, needles and topsoil of the site.
As that permafrost thaws, the ground above it can sink, knocking trees askew and forming pools of water called thermokarst lakes.
Methane bubbles pop on the surface of a lake near Fairbanks, Alaska.
Thawing permafrost in the lakebed soils releases old carbon, which microbes eat up and turn into methane. There are bubbles popping up among the reeds, like bubbles from a fish tank aerator. Some of them are not growing in the directions trees normally do.
by Kate Ramsayer / FAIRBANKS, ALASKA / At first glance, it looks like a typical, picture-perfect lake.
But scan the reeds along the shore of this pool on the outskirts of Fairbanks, or glance at the spruce trees lining the banks, and you notice something different is going on.
It is too soon to know whether the discovery will seriously upset the estimated dates of events like the arrival of human beings in the Western Hemisphere, scientists said.