EXPLANATION OF THE ILLUSTRATION 
Plate 1. Fossil oak wood, approximately 4500 years old, from the Boylston 
Street Fishweir deposits, Boston, Massachusetts. Wood silicified with ethyl 
silicate and then polished on one transverse surface with cerium oxide 
powder. Specimen appearing in Figures 2 through 4 was further treated by 
partial etching of silica with concentrated hydrofluoric acid. Original wood 
was not mineralized. 
Fig. 1. White light photograph of stem cross-section. Radial fractures re- 
sulted from accidental breakage in handling. Magnification: ca. X2. 
Fig. 2. Scanning electron micrograph (SEM) of a polished transverse sur- 
face sectioned from the specimen illustrated in Figure 1. X300. 
Fig. 3. Enlargement of a portion of the surface shown in Figure 2. SEM. 
X600. Note deposits of silica in lumina of the prosenchymatous cells. 
Fig. 4. Further enlargement of the above, emphasizing silica deposit in 
lumen of the vessel element. SEM. X1200. 
34 
