Word: ellicott
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Dates: during 1940-1949
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Tree Rings. Dr. Andrew Ellicott Douglass, University of Arizona astronomer, is the founder of the 20th-century science of "dendrochronology"-telling time (in years) by means of tree rings. The thickness of the annual growth rings in trees is proportional to the year's rainfall. Thus the rings fall in patterns corresponding to the varying rainfall supplies during the life span of the tree. By matching patterns from logs of recent date to successively older & older specimens, Dr. Douglass carried a continuous record back several hundred years. Examining logs in the ruins of Indian pueblos built before Columbus...