Clark Wissler of the American Museum of Natural History can be credited as one of the first individual scientists to realize the importance of such naturally occuring rings in trees can be used to tell how old it is. Pith is found at the center of the tree stem, then rings can bee seen followed by a layer that insulates between what is called vascular cambium (the source of xylem and phloem) and the outer appearance of the tree, or its bark.
Each year a new layer of xylem is produced, thus giving us the tree rings we all can observe and count.
The purpose of this lab is to learn the basic field, lab, and computational procedures necessary to conduct dendrochronological research.
For example, if rainfall is the limiting factor than tree rings, or essentially tree growth is reliant upon the factor of rainfall.The aggregate tree growth principle states that many conditions, both natural and human induced are responsible for any one tree-ring series growth pattern.The uniformitarian principle is the assumption that present day physical and chemical processes responsible for the environmental change that producet tree-ring formations is the same today as it has been in the past.The limiting factor principle is one which states that rings can only form as fast as the limiting factor.A tree-ring series found in certain species of trees that have high survivability near desert like conditions would mean that a dendrocrhonologists could deliberately sample those trees to glean past drought conditions.
Essentially what is the most practiced principle is comparing dates of tree-ring series from one tree to many other trees from a different location.Once tree rings from one general area are compared with corresponding patterns observed in another area it is compiled as a set of data and crossdating has been achieved.Through many over-lapping ring chronologies, what is called a master dendrochronology can be defined and used to interpret past conditions more precisely.By using dendrochronology scientists have dated certain living trees or their root systems in certain cases as having ages in excess of what is expected given the Biblical chronology of the global flood.National Geographic reported in April of 2008 These types of findings are used by evolution proponents to aid their debate in silencing anything related to Biblical chronology.These tree-rings are wood cells formed within a year or growing season, thin walled cells formed in the early growing season (earlywood) and thicker walled cells produced later in the growing season (latewood).