/iccount of a Remarkable Fossil’ Tree. 287 
where portions of it have been disengaged, and carried 
away ; but-no portion of what remains is elevated more than 
afew inches above the surface of the rock. It is owing, 
however, to those partial disturbances, that we are enabled 
to perceive the columnar form of the trunk—its cortical lay- 
ers—the bark by which it is enveloped, and the peculiar 
cross fracture, which unite to render the evidence of its lig- 
neous origin, so striking and complete. From these charac- 
ters and appearances, little doubt can remain that it is refer- 
able to the species juglans nigra, a tree very common to the 
forests of the Illinois, as well as to most other parts of the 
immense region drained by the waters of the Mississippi. 
The woody structure is most obvious in the outer rind of 
the trunk extending to a depth of two or three inches, and 
these appearances become less evident as we approximate 
the heart.. Indeed, the traces of organic structure in its in- 
terior, particularly when viewed in the hand specimen, are 
almost totally obliterated and exchanged, the vegetable mat- 
ter being replaced by a mixed substance analagous in its ex- 
ternal character, to some of the silicated and impure calca- 
reous carbonats of the region. Like those carbonats, it is 
of a brownish grey colour, and compact texture, effervesces 
slightly in the nitric and muriatic acids, yields a white streak 
under the knife, and presents solitary points, or facets of 
crystals resembling calc spar. All parts of the tree are pen- 
etrated by pyrites of a brass yellow colour, disseminated 
through the most solid and stony parts of the interior,—fill- 
‘ing Interstices in the outer rind, or investing its capillary 
pores. ‘There are also the appearances of rents or seams 
between the fibres of the wood, caused by its own shrink- 
age, which are now filled with a carbonat of lime, of a white 
colour, and crystallized. 
‘There is reason to conclude that the subject under con- 
sideration, is the joint result partly of the infiltration of min- 
eral matter into its pores and crevices prior to inclosure in 
the rock, and partly to the chemical action induced by the 
great catastrophe by which it was translated from its parent - 
forest, and suddenly enveloped in a bed of solidifying sand. 
With respect to the difference which exists between its ex- 
ternal and internal structure, we may suppose that it had 
partially submitted to decay, and: became hollow, before the 
process of petrifaction commenced, .and. that the interior 
