The temperature of the burial environment contributed as well.

Chemical reactions, including the biological reactions of decomposition, proceed more slowly at lower temperatures.

The cool temperatures of the coastal Northwest, especially in the partially shaded deposit covered by forest, slowed the rates of whatever anaerobic decomposition was occurring.

The specific chemistry of the organic materials also mattered.

Wood contains compounds, particularly lignin, that are relatively resistant to decomposition even in anaerobic conditions.

While wood does degrade over geological time even in anaerobic settings, over the 500 years of the Ozette burial, the degradation was slow enough that the structural integrity of many objects was maintained, even though they absorbed water to replace the original cellular structure.