Tree ring dating and archaeology
Tree-ring analysis requires observation and pattern recognition.
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.
In his Trattato della Pittura (Treatise on Painting), Leonardo da Vinci was the first person to mention that trees form rings annually and that their thickness is determined by the conditions under which they grew. S., Alexander Catlin Twining (1801–1884) suggested in 1833 that patterns among tree rings could be used to synchronize the dendrochronologies of various trees and thereby to reconstruct past climates across entire regions.
During the latter half of the nineteenth century, the scientific study of tree rings and the application of dendrochronology began.
The sessions room at the northern end of the current pub is of brick construction probably built over a cart entrance in the early 19th Century.
The Olde Boar’s Head stands to the west side of Long Street, in Middleton (the A664 Middleton to Rochdale road), at its junction with Durnford Street (SD 87052 06266, Figs 1a/b).
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.
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 dating works because a tree grows larger--not just height but gains girth--in measurable rings each year in its lifetime.
Dendrochronology (or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed in order to analyze atmospheric conditions during different periods in history.
Dendrochronology is useful for determining the timing of events and rates of change in the environment (most prominently climate) and also in works of art and architecture, such as old panel paintings on wood, buildings, etc.
Dendrochronology is the formal term for tree-ring dating, the science that uses the growth rings of trees as a detailed record of climatic change in a region, as well as a way to approximate the date of construction for wooden objects of many types.
As archaeological dating techniques go, dendrochronology is extremely precise: if the growth rings in a wooden object are preserved and can be tied into an existing chronology, researchers can determine the precise calendar year--and often season--the tree was cut down to make it.