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Archaeological wood

 
     
    Deterioration in Historic and Archaeological Wood
 

Our past research on microbial and enzymatic degradation of wood and wood components has provided a great deal of information that has been useful in helping to protect and conserve historic and archaeological wood. In addition to our investigations on biological and non-biological degradation processes in the expedition huts of Antarctica (link to Antarctic research), studies have been done or are currently underway with The Getty Conservation Institute, The Metropolitan Museum of Art, The American Museum of Natural History, the U. S. National Park Service, The Institute for Nautical Archaeology, as well as many archaeologists and conservators working to preserve wooden cultural properties around the world.

A few projects are listed here to demonstrate how our research is being used to better understand deterioration processes that affect ancient woods and to help preserve these national and international heritage sites long into the future. Our research is also providing important new information on the biology and ecology of these little known microorganisms that attack ancient wooden objects and other organic materials.



Ancient Egyptian Wood

An ancient Egyptian wooden statue (2340 B. C.) from a tomb in Saqqara now in the Metropolitan Museum of Art, New York. Photo courtesy of the Metropolitan Museum of Art.
 
Transmission electron micrograph of a section from the Scribe of Mitre Statue showing severely degraded cell walls caused by a brown rot fungus. The attack occurred in the tomb before excavation. The wood is extremely weak and easily fractures into dust-like particles. Our research provides information on the types of decay found in ancient tombs and is used by conservators to determine the most appropriate methods of preserving the ancient cultural properties.

For more information on deterioration in ancient Egyptian woods see pdf file of: Blanchette et al. Assessment of deterioration in archaeological wood from ancient Egypt. Journal of the American Institute of Conservation 33:55-70.

 

 

 

 


Waterlogged Woods From Ancient Shipwrecks

Underwater excavation of the Uluburun, a 14th century B. C. Late Bronze Age shipwreck, by Cemal Pulak, Photo courtesy of the Institute of Nautical Archaeology. In addition to wood from the ship, ebony logs that were part of the ships cargo were also found.

 



Scanning electron micrographs of sections from the ship hull showing extensive bacterial degradation of the wood cells. Bacterial attack of waterlogged wood causes loss of wood strength. The wood cells shown in the bottom photo are distorted and have collapsed due to the lack of cell wall integrity.

 

More information on decay of waterlogged archaeological woods can be found at:
Blanchette, R. A. 2000.A review of microbial degradation found in archaeological wood from different environments. International Biodeterioration and Biodegradation 46:189-204.

 


Deterioration in Thomas Edison's Historic Laboratory


A view of Thomas Edison's historic laboratory in Fort Myers, Florida.

 


 


An unusual type of wood deterioration was found to be taking place in the laboratory. This damage was caused by a caustic chemical spill that occurred long ago and resulted in a slow defibration of the wood. Over many years, very serious damage has resulted.

 


The chemical corrosion of the wood over many decades resulted in wood cells detaching and separating into a fibrous mass. This scanning electron micrograph demonstrates the degradation took place in the middle lamella between the cells leaving only the secondary wall layers of the wood cells .

 


Tumulus MM - The Ancient Tomb of King Midas


This large mound in Turkey called Tumulus MM, thought to be the tomb of King Midas, contains the largest wooden tomb ever found. No gold was found in the tomb but spectacular furniture, a massive coffin with the King and many other items were discovered in the tomb that dates to 700 B.C.
 

 

Our investigations have shown that a soft rot type of wood destroying fungus was responsible for the decay in the tomb and this ancient fungus was likely causing decay for hundreds, possibly thousands of years.


For additional information on:
The fungi in the tomb see:
Filley, T. R., R. A. Blanchette, E. Simpson and M. L. Fogel. 2001. Nitrogen cycling by wood decomposing soft-rot fungi in the “King Midas tomb”, Gordion, Turkey. Proceedings of the National Academy of Science 98: 13346-13350.

Information on how this research has help conservators find the best treatments to preserve the wood see:
Spriydowicz, K., E. Simpson, R. A. Blanchette, A. Schniewind, M. Toutloff and M. Murray. 2001. Preserving dry archaeological wood with polyvinyl acetal resins: a case study. Journal of the American Institute of Conservation 40:43-57.

Information on decay and pseudomorphs produced in the tomb see:
Blanchette, R.A. and E. Simpson. 1992. Soft rot decay and wood pseudomorphs in an ancient coffin (700 BC) from tumulus MM at Gordion Turkey. International Association of Wood Anatomists Bulletin. 13:201-213.

 

When the tomb was opened the bones of the King were found on a massive cedar coffin within the wooden tomb structure. Huge cut pine timbers formed the walls of the tomb with cedar timbers used for the floor. This inner wooden tomb structure was also covered by large juniper logs. Decay was evident in the structure and wooden contents of the tomb. Photo is courtesy of the University Museum, University of Pennsylvania.

Scanning electron micrograph of a section from the decayed wood showing a soft rot attack. This fungus caused cavities to form within the cells walls of the wood. Our investigations have also shown that the fungus was able to tolerate very adverse conditions and obtained nitrogen needed to decay the wood from the King's body. Carbon and nitrogen isotope analyses show the King's nitrogen was translocated by the fungus into the floor, walls and even the ceiling of the tomb as it attacked the wood. Throughout the tomb only one type of decay was found.

This work was done in cooperation with Professor Timothy Filley from Purdue University; Professor Elizabeth Simpson, Director of the Gordion Furniture Project, Bard Graduate Center for Studies in the Decorative Arts, New York; Professor G. Kenneth Sams, University of North Carolina; The Department of Antiquities, Ministry of Culture of the Turkish Republic and the Museum of Anatolian Civilization, Ankara, Turkey.


Prehistoric Great Houses of the Southwestern United States

Research is underway at Chaco Culture National Historic Park and Aztec Ruins National Monument in New Mexico to assess the types and extent of deterioration currently occurring in the wood of the great houses, determine the wood species used in their construction and evaluate reburial methods currently being used to preserve some of the great houses that are rapidly deteriorating. Although the Chacoan great houses were made of mud brick, they also contained large quantities of wood in their construction. Tens of 1000s of trees were used for beams, secondary roof supports and door and window lintels. Today, these great houses have one of the largest samples of prehistoric wood left of any site in the American Southwest. In the West Ruin of Aztec Ruins National Monument alone, over 6000 pieces of wood still exist. The wood is an integral part of the surviving Chacoan architecture and has served as a valuable resource for determining the exact age of the structures and for obtaining information about raw material production, procurement and harvesting methods.

 

View of Pueblo Bonito at Chaco Canyon, New Mexico


Chetro Ketl, a great house at Chaco Canyon, showing large wooden beams in the ruins.


Wood from one of the lintels that has been decayed. Both brown rot and soft rot fungi have been found in the great houses.


Salt deterioration also is causing problems on some woods. This beam has been deteriorated by salts that have precipitated on the exposed wood over many years.


The same area of Chetro Ketl shown in the above photo that has been reburied to preserve the mud brick and wood in the great house.

 

 

 

 

 

 

The reburial of archaeological sites as an effective conservation strategy to protect masonry structures and wood is currently being used to insure preservation of the Chacoan prehistoric structures for the future. For these programs to be successful, the agents responsible for deterioration and the reburial environment are being studied so that conservation plans will effectively prevent future biological and non-biological deterioration from taking place. These investigations, in cooperation with the Getty Conservation Institute and the National Park Service, will monitor the reburied sites over time to insure the environment is not conducive to decay and the buried wood is being protected from degradation.

 

For additional information on conservation of the prehistoric great houses, wood used in the structures and deterioration taking place see:

Blanchette, R. A., B. W. Held, J. A. Jurgens. 2004. Wood Deterioration in Chacoan Great Houses of the Southwestern United States. Conservation and Management of Archaeological Sites 6:204-212.

Ford, D., M. Demas, N. Agnew, R. Blanchette, S. Maekawa, M. Taylor and K. Dowdy. 2004. Chaco Canyon reburial programme. Conservation and Management of Archaeological Sites 6:177-202.

Follow this link for results from studies on wood identification in the Chacoan great houses


©2015 Robert Blanchette. All Rights Reserved.