Accouat of a Remarkable Fossil Tree- 289:: 
species of petrification-to ‘be found. At a short distance. 
above, where the. bed. of the Des Plaines approaches nearer 
the summit level, limestone ensues, and continues from. that 
point northward to the shores of lake Michigan. . Inthe vi- 
cinity of Chicago, where this limestone is quarried for eco-., 
nomical purposes, it is characterized by the fossil remains of; 
molluscous, and other aquatic animals. fr 
‘* There exists a watér communication between the head : 
of Jake Michigan and. Chicago, and the river Des Plaines, . 
during the periodical rises of the latter, but its summer level. 
is about seven feet lower, at the termination of the Chicago, 
portage, than the surface of the lake. From this point to its. 
junction with the Kankakee, a computed distance of fifty. 
miles, the bed of the Des Plaines may be considered as hay-. 
ing a mean southern depression of ten inches per mile, so 
that'the floetz rocks ‘at its mouth, lying on.a level of forty-. 
eight feet eight inches below the ‘surface of lake Michigan, 
have an altitude, which cannot vary far, from five hundred 
and fifty feet above the Atlantic. There are no mountains 
fora vast distance either east or west, of this stream: it isa. 
country of plains, in which are occasionally to be seen allu- 
vial hills-of- moderate elevation; but the most striking ine- 
qualities of surface proceed fon the streams which have. 
worn their deep-seated channels through it; and an oceanic, 
overflow, capable. of covering the eountry, and producing. 
these strata by deposition, would also submerge all the. im-, 
mense tracts of secondary and alluvial country, between the, 
Alleghany and the Rocky Mountains, converting into an arm. 
of ‘the -sea, the great valley of the Mississippi, from the 
Gulph of Mexico north, to the Canadian lakes. We find in 
the alluvial soil along the Illinois and Des Plaines, blocks of 
granite, hornblende, and gneiss, exhibiting the same appear- 
ances of attrition, and of having been transported from their. 
parent beds, which characterize the secondary table lands 
along the margin of the great American lakes, iis prairies of 
Illinois,-and the western parts of New-York. 
~The country along both banks of the river Des Plaines, 
at the spot where this imbeded fossil tree. occurs, is a level 
and beautiful. prairie, covered. with a luxuriant growth of 
grass, and interspersed with small groves of oaks and hicko- 
ories—the quercus alba, and uglans dies i of the Amer- 
ream forest. uC 
