Public Release: 

EARTH: Growth rings in rocks reveal past climate

American Geosciences Institute

Alexandria, VA - For years, scientists have used mineral, sediment and ice layers, deposited intermittently throughout geologic time, to track the global climate record. These can come from caves, lakes, the oceans and ice sheets. But over the course of the last decade a new method has been developed that presents an opportunity for geoscientists to assess global climate history in almost any arid landscape.

The technique relies on testing a thin, sometimes only millimeters thick, layer of calcite that precipitates on rocks as rainwater filters through the ground. This method of dating the growth-ring-like layers called pedothems has improved with advances in instrumentation. Using rocks extracted from a soil trench, scientists have reconstructed a climate record for western North America. Find out if this record is in agreement with other climate records in EARTH Magazine:

The 2016 May issue of EARTH Magazine is now available at, and is filled with stories from around the geoscience community. Included are stories about China's Red Deer Cave people, the first all-digital geologic map of Alaska and a link between global climate and mid-ocean volcanic ridges. All this and more in EARTH Magazine.


Keep up to date with the latest happenings in Earth, energy and environment news with EARTH Magazine online at: Published by the American Geosciences Institute, EARTH is your source for the science behind the headlines.

The American Geosciences Institute is a nonprofit federation of geoscientific and professional associations that represents more than 250,000 geologists, geophysicists and other earth scientists. Founded in 1948, AGI provides information services to geoscientists, serves as a voice of shared interests in the profession, plays a major role in strengthening geoscience education, and strives to increase public awareness of the vital role the geosciences play in society's use of resources, resiliency to natural hazards, and interaction with the environment.

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