perfectly sound (Harlow, 1970). Wooden stakes driven into 
anaerobic muds over 4,500 years ago, when recovered and 
examined, were found to be histologically intact and recogniz- 
able as to botanical taxa (Bailey and Barghoorn, 1942; Barg- 
hoorn, 1949). These samples, though highly depleted in 
holocellulose, retained essentially all of their lignin, albeit 
chemically modified (Jahn and Harlow, 1942). 
Under anaerobic conditions, lignin is the most decay- 
resistant constituent of the woody plant cell wall (Varossieau 
and Breger, 1952). Most fossil woods show an increase in the 
lignin/holocellulose ratio relative to their contemporary coun- 
terparts, Infact, specimens of Eogene age and older are usually 
completely devoid of holocellulosic material. This observation 
reflects the great difference in susceptibility of the two major 
structural components of wood toward biological degradation 
and chemical alteration under the conditions ordinarily atten- 
dant in nature. Among the polysaccharides, cellulose is more 
resistant to decay than the hemicelluloses. 
The fungi which attack wood can tolerate a comparatively 
wide range of pH, from at least 4 to perhaps as high as 9, but 
their most active growth generally occurs within the region 
between 4.5 and 7 (Browning, 1963, and Kaarik, 1974). Beyond 
the limits of pH favorable for fungal activity, wood decomposi- 
tion through chemical hydrolysis is greatly accelerated. This is 
especially true for environments of high alkalinity, as solutions 
of strong bases will dissolve a considerable quantity of wood 
substance, even at ordinary temperature (Browning, 1963). 
Hence, preservation of unmineralized wood in sedimentary 
settings of high alkalinity is precluded. 
For further discussion of the chemistry and microbiology of 
decay, the articles by Kaarik (1974), Kirk (1973), and Scheffer 
(1973) are recommended. For further information relating to 
the chemistry of fossil wood, see the references cited by Sen 
and Basak (1957) in their review of the topic. 
Ancient Wood in the Sedimentary Record 
Commonly, fossilization is initiated by the entombment of 
fresh wood within soft muds beneath a body of water receiving 
a substantial influx of sediment. The initial stage for many of 
the fossil woods that are preserved as silicified woods appears 
to be rapid burial in volcanic ash (Murata, 1940). Both of these 
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