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A lesson plan for grade 5 Science Provided by Research Laboratories of Archaeology (Ward, H. Archaeologists sometimes study the ring patterns in beams or other pieces of wood from archaeological sites to help date the sites; they may also study the ring patterns to infer the local climatic history. Time Before History: The Archaeology of North Carolina. Designed for grades four through eight, the web edition of this book covers fundamental concepts, processes, and issues of archaeology, and describes the peoples and cultures of the Paleoindian, Archaic, Woodland, and Mississippian periods.First he studied recently cut trees whose dates he knew.This initial step was critical because by knowing the cut date, Douglass knew when each tree added its last growth ring.He observed that the year a tree was chopped down could be determined by matching its ring pattern with the pattern of a tree whose cut year he knew.For example, say Douglass observed on his preliminary sequence that a drought occurred in 1900, appearing on trees as a very narrow growth ring.At that point, determining the year the tree was chopped down was, again, straightforward.
Also, the East’s humid, temperate climate decays wood beams quickly, so a sequence is limited in how far back in time it reaches.
Nonetheless, scientists find they can construct limited sequences for certain tree species in places where seasons are more pronounced or the rains less dependable.
One kind of tree whose chronology can be charted is the oak in the higher reaches of the Appalachians.
In their study of dendrochronology, students use activity sheets and a discussion to apply principles of dendrochronology to determine a tree's age and to recognize climatic variation. (den-droh-cruh-NOL-uh-gee) means “the study of tree time.” Usually called tree-ring dating, dendrochronology is a science based on the fact that every growth season a tree adds a new layer of wood to its trunk.
They will also analyze and experience how archaeologists can sometimes use tree rings to date archaeological evidence and study past climates. Over time, these yearly growth layers form a series of light and dark concentric circles, or tree rings, that are visible on cross sections of felled trees.By counting the dark ring segments, scientists can tell a tree’s age if the cross section of the trunk is complete. Based at the University of Arizona in Tucson, Douglass wanted to know how sun spot activity affected climate, and his research soon led him to pioneering tree-ring analysis.