Preservation or decay of artefacts is the result of environmental and natural conditions that affect the materials from which artefacts are made. Really, it’s all about chemistry…
Environments particularly GOOD for the preservation of certain artefacts
* Dry or desertic environments: you simply have to think of Egypt or the Sudan… the environment and the temperature in those countries are very, very dry. Large quantities of artefacts and lots of organic material have been superbly preserved in such dry environment because they do not rot.
* Salty soils: just imagine of salted fish or meat… the reason the fish or the meat is not rotting is because of the salt, which has been used to dry it. Salt helps inhibit biological decay.
* Waterlogged environments: certain artefacts can survive underwater (hence why there is such a thing as underwater archaeology), as long as they are constantly immersed in water.
* Anaerobic environments: try to imagine a vaccum-sealed package or a can… an anaerobic environment is an environment where there is very little oxygen. The lack of oxygen will lead to the preservation of organic matter because decay is slowed or halted.
* Frozen environments: the food you put in the freezer will last much longer in its frozen state than food left in the refridgerator. The same applies to certain artefacts and organic materials found in ice.
Environments particularly BAD for the preservation of certain artefacts
* Wet or humid environments: think of a tropical rainforest, where is it hot, wet, and humid… The fluctuation between heat, wetness, and constant humidity will increase the decaying or the corrosion process. Not much can survive these kinds of environments.
* Acidic soils: acids are very powerful chemicals and acids in soils will even cause inorganic materials (like the mineral portion of bone) to dissolve and cause metals to corrode.