Gideon Algernon Mantell, The Medals of Creation, Volumes 1 and 2
“ But incrustations are not petrifactions; stems and branches of trees, skulls, bones, shells, &c., are simply invested with a calcareous coating or crust, which is generally porous and friable, but often crystalline and compact. The inclosed bodies are not permeated by the stony matter; if the mass be broken, or the incrustation removed, we find the twig, or stem, either dry and shrivelled, as in the specimens, figs. 2, 3, 4, Plate III.; or tubular cavities are left by the decay and removal of the vegetable structure, as in fig. ”
