Dating introduction ring tree
This, in turn, let him determine the year each tree started growing.The calculation was straightforward: count the dark rings inward and subtract that number from the year the tree was cut.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.Tree-ring analysis requires observation and pattern recognition.To the eye, the sequence looks like a series of parallel lines, with the width between each line the same as the width of each tree ring.Known dates are matched to the tree rings on the sequence.Nonetheless, scientists find they can construct limited sequences for certain tree species in places where seasons are more pronounced or the rains less dependable.
Also, the East’s humid, temperate climate decays wood beams quickly, so a sequence is limited in how far back in time it reaches.Douglass extended this bridging exercise by studying ring patterns visible in old wooden beams, some preserved in the pueblos (houses) of early Native Americans living in his study area.Ultimately, he charted a tree ring sequence to about 500.Each year a tree’s growth ring has two parts; one is wide and light colored, and the other is narrow and dark. This grows during the wet spring and early summer when the tree has a lot of sap, and the cambium cells giving rise to the trunk growth are large and thin walled.
As the summer winds down and the transition to the cooler autumn occurs, the tree’s growth rate slows.From recording tree-ring patterns in several geographic areas, scientists have found that all the region’s trees have the same pattern. He reasoned if he could trace patterns far enough back in time, he could outline a history of regional climate and see if sun spots could be related.