Dendrochronology
Dendrochronology (word derived from Greek , dendron, "tree limb"; , khronos, "time"; and , -logia) was developed during the first half of the 20th century originally by the astronomer A.E. Douglass, who founded the Laboratory of Tree-Ring Research at the University of Arizona. Douglass researched sunspot activity. He expected changes in solar activity would affect climate patterns on Earth. The climate would be recorded by tree-ring growth patterns.