In ca. 700-year-old woods, pine and fir, dug out from a 2-m deep soil layer, pH 7.75, wood losses were 55.8 and 26.4%, holocellulose losses 74.35 and 24.2%, hemicellulose losses 90.4 and 44.8%, cellulose rises in holocellulose 36.7 and 9.70/6, cellulose left 34.9 and 83.2%, lignin lost 24.7 and 21.4%, max. moisture 473 and 318%, mineral content tripled.. Conditions close to anaerobic favored mineralization and extraction with water. Carbohydrate degradation was more advanced in pine than in fir. More than 20% of lignin decomposed in either wood. Lignin structure modifications occurred via demethylation, depolymerization, and autocondensation.