Uranium from the surrounding bedrock seeps into the water and forms a carbonate that becomes part of each layer of the speleothem as it forms.
Beyond their breath-taking beauty, the formations in Carlsbad and the more than 100 other caves in the area provide a record of rainfall in the southwestern United States.
Tucked away inside the Earth, the rocks are protected from the weathering and large-scale erosion that taints other land-based climate records.
However, the reservoir effect may be of minor importance when compared to contamination with younger carbon.
by Holli Riebeek · design by Robert Simmon · June 28, 2005 The first pieces of evidence for climate change came from the land itself, from the misplaced boulders scattered across much of the Northern Hemisphere, though there were other signs as well.
Little growth might indicate a drought, just as rapid growth could point to heavy precipitation.