CHAPTER IV.

=THE PRESERVATION OF PLANTS AS FOSSILS.= Pp. 54–92.

Old surface-soils. Fossil wood. Conditions of fossilisation. Drifting of trees. Meaning of the term ‘Fossil.’ Incrustations. Casts of trees. Fossil casts. Plants and coal. Fossils in half-relief. Petrified trees. Petrified wood. Preservation of tissues. Coal-balls. Fossil nuclei. Fossil plants in volcanic ash. Conditions of preservation.