Geology of Upper Illinois. 143 
to the Wabash, in Indiana, at a point several miles above La 
Fayette.* 
We are now prepared to enter upon a more minute description 
of the geological features of the country, contiguous to the wes- 
tern termination of the canal, where the coal in particular is 
largely developed. To render the subject the more easily intelli- 
gible, a sketch of the region, together with a cross section exhib- 
iting the north bluff of the Illinois river, from Ottawa to Spring 
creek, are subjoined. 
SECTION. 
ro 
. 6 
x = 
f E = 3 
a) o = .> 
> = es 
2 ‘ z ca 
= ae Bm 
x = o 
a a a 6a 
} ij 
a i : 
: 
TAY 
“In speaking of the boundary of the coal-field, I wish to be understood in gen- 
eral, as treating of its line of junction with the magnesian limestone. Whether 
the coal-beds run out against this rock, or are continued beneath it, no facts have 
yet been observed in this country sufficient to show. The extent of the magne- 
