288 Account of a Remarkable Fossil ‘Tree.’ 
substance and the cale spar, were deposits from particles sol+ 
uble, or intimately mixed with ‘water, previous to the in- 
closure of the tree'm its rocky envelope. Ze 
“ At the time of our visit (August 13, 1821,) the depth of 
water upon the floetz rocks forming the bed of the river 
Des Plaines, would vary from one to two feet; but it will’ 
be recollected that it was at aseason when these higher trib~ 
utaries, and the Illinois itself, are generally at their lowest 
stage: Like most of the confluent rivers ‘of the Mississippi, 
and their tributaries, the Des Plainesis subject to great fluc- 
tuations, and during its periodical floods may be estimated 
to carry a depth of eight or ten feet of water to the junction: 
of the Kankakee. At those periods the water is also ren- 
dered turbid by’ the ‘quantity of alluvial matter it carries” 
down, and a search for this organic fossil, mtist prove unsue= 
cessful. But during the prevalence of the summer droughts, 
in ‘an atmosphere of little humidity, when the waters are 
drained to the lowest point of depression, and acquire the 
greatest degree of transparency, it forms a very conspicuous 
trait m the geology of the stream, and no person, seeking 
the spot, can fail to be directed to it. Although correspon- 
ding in its direction to the apparent course of the formation 
m which it rests, it forms an acute angle with the natural seams 
and fissures which chequer the surface of the rock; and from 
an effect analogous to carbonization, the exterior rind and bark 
of the tree, have acquired a blackish hue, while the inclosing 
rock, being a light grey, presents a contrast that i 18 teense 
te arrest the attention of the observer.” 
The sand stone rock in which this fossil tree reposes, “ is 
every where found in a horizontal ‘position, and differing on- 
ly with respect to’ hardness, and yagi OF ieee which do 
notnecessarily imply a different formation. | The remains of 
fossil organized bodies in this stratum, are not abundant, or 
have not’ been successfully sought’; and it appears to be 
wholly wanting in the various species of concholites so plen- 
tifully imbedded in the calcareous formation which rests: up- 
on it.) It is _probable that future observations will prove, 
that its organic conservata are chiefly referable to the vege 
table kingdom. ‘It is certain, that this inference is justifi- 
ed by the facts which are before me, and particularly by the, 
characteristic appearances of the ‘strata in the bed of thé 
river Des Plaines, where the imbedded walnut, is the only 
