Cross dating in dendrochronology douglass
Much of this work focused on regions in the arid Southwest where ancient pinyon pines still live or exist as beams in old houses.
Douglass used a bridging method to create his chronology.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.Another kind is the bald cypress, which grows well in wet areas like coastal swamps.Dendrochronologists make master tree-ring sequences by drawing vertical lines on a piece of paper at the end of every tree ring.
(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.