Help defend free speech and free scientific inquiry in the U.S.
Sign the Academic Freedom Petition.

Dendrochronology

From CreationWiki, the encyclopedia of creation science

(Redirected from Tree rings)
Jump to: navigation, search
Comparison of ring patterns can often illustrate missing rings produced by regional factors such as stress.
Comparison of ring patterns can often illustrate missing rings produced by regional factors such as stress.

Dendrochronology (also called tree-ring dating) is a technique of dating past climatic changes through a study of tree ring growth. Each year a tree adds a layer of wood to its trunk and branches thus creating the annual rings we see when viewing a cross section. Wide rings are produced during wet years and, narrow rings during dry seasons. These changes in tissue formation can be used to calculate age of the wood itself or surrounding archaeological artifacts.

Contents

History

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. Wissler worked with A. E. Douglass now considered the father of dendrochronology at the University of Arizona to further studies and solidification of such dating as a worthwhile scientific endeavor. [1] [2]

Tree-Ring Formation

Diagram of rings in a young conifer.
Diagram of rings in a young conifer.

Phloem is a tissue type substance, along with xylem, that can be found within trees, being responsible for transporting water and mineral nutritients, from the root of vascular plants, distributing it to the necessary parts. [3] 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 (also known as xylem or 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. 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).

Apparent old ages

Tree rings in Mexican Cypress (Cupressus lusitanica).
Tree rings in Mexican Cypress (Cupressus lusitanica).

By using dendrochronology scientists have dated certain living trees to having ages in excess of what is expected given the Biblical chronology of the global flood. Gerald Aardsma found that trees can produce multiple rings in a wet year. In the lab Walter Lammerts was also able to show that trees can also display extra rings in short drought periods.[4]

Principles of Dendrochronology

Theroccurringe are seven dendochronological principles that contain certain assumptions, that are used as a framework or theory to interpret tree-ring data. The most prominent of such assumptions, uniformitarianism is also an assumption that is quite prevelant within evolutionary science.

Uniformitarian

The uniformitarian principle is the assumption that present day phsycial and chemical processes responsible for the connection of enviornmental change and tree-ring formation is the same today as it has been in the past.

Limiting Factors

The limiting factor principle is one which states that rings can only form as fast as the limiting factor. For example, if rainfall is the limiting factor than tree rings, or essentially tree growth is subordinate to the limiting factor of rainfall.

Aggregate Tree Growth

The aggregate tree growth principle states that many conditions, both natural and human induced are responsible for any one tree-ring series growth pattern. Many factors of a tree growth patterns have to be taken into account, however in some cases one factor may be left out as potential data due to isolation of a different factor that requires study.

The four factors taken into account are:

  1. Tree growth related to normal physiological aging processes within the tree itself.
  2. Climate or weather induced factors.
  3. Outside of the forest factors such as disease, or insect problems.
  4. Random natural or human caused processes that effect tree growth.

Ecological Amplitude

The principle of ecological amplitude recognizes the ability for different species of trees to grow in many locations or specialized habitats. This is important to consider because useful trees for dendochronology are often found near zones of their natural range.

Site Selection

The site selection principle recognizes that certain species of trees propagate and sruvive better in certain conditions than others do. A tree-ring series found in certain species of trees that have high survivability near desert like conditions would mean that a dendocrhonologists could delibrately sample those trees to glean past drought conditions.

Crossdating

The most practiced principle of dendrochronology is achieved through comparing dates of tree-ring series from one tree and many other trees from a different location. Once tree rings from many separate trees are obtained within the same general area and those with corresponding or comparable patterns are observed and then compiled as a set of data 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. [5]

Replication

The principle of replication states the need of more than one stem radius per tree and more than one tree per site. Essentially samples will range up to many trees per site or even many sites of trees. This is an attempt to identify and minimize noise or environmental factors of little interest. [6] [7]

References

  1. ↑ Dating Techniques; Dendochronology Minnesota State Universiy
  2. ↑ "dendrochronology." Encyclopædia Britannica. 2008. Encyclopædia Britannica Online. 8 Jan. 2008 [1]
  3. ↑ Xylem by Wikpedia
  4. ↑ Tree Rings and Biblical Chronology ICR IMPACT No. 252 June 1994 by Frank Lorey, M.A.
  5. ↑ Crossdating - The Basic Principle of Dendrochronology by Lori Martinez, Laboratory of Tree-Ring Research, and The University of Arizona.
  6. ↑ Principles of Dendochronology Henri D. Grissino-Mayer's Ultimate Tree-Ring Web Pages
  7. ↑ Principles of Dendocrhonology by Henri Grissino-Mayer of the Laboratory of Tree-Ring Research at the University of Arizona, Tucson

External Links

Creationist links

Secular links


Browse


See Also

v • d • e
Chronology
Feature articles
Categories · Portal
Retrieved from "http://www.creationwiki.org/Dendrochronology"
Personal tools