Heading for Cincinnati, I left Columbia this morning and traveled in the wake of a storm system that rumbled through Missouri during the preceding hours. By the time I caught up with the storm, in St. Louis, it was clearly moving on to the northeast and I elected to take the southern route to Ohio, using Interstates 64 and 71.
After crossing the broad, floodplain of the Mississippi, I-64 climbs into the rolling farmlands of southern Illinois; cropfields and wooded stream channels characterize this region which, this morning, was brightened by scattered fields of yellow mustard. The swollen Wabash River marked my entry into Indiana, where the Interstate begins to parallel the Ohio River, some 10-15 miles to the south. Just beyond the outskirts of Evansville, the highway climbs into the Shawnee Hills, which have eroded from a thick layer of Carboniferous sandstone and limestone; the southern section of this geophysical province dips into north-central Kentucky where Mammoth Cave penetrates its eastern rim.
Dropping from the Shawnee Hills, I-64 crosses the Ohio at Louisville and continues on toward Lexington. I picked up I-71 and, just east of Louisville, entered the Bluegrass Region (the Lexington Peneplain), with its bedrock of Ordovician shales and limestones; numerous roadcuts and stream valleys expose these sedimentary rocks along the Interstate. Paralleling the Ohio, the highway angles to the northeast and undulates toward Cincinnati, crossing many tributaries of the Ohio en route; the largest of these is the Kentucky River, which rises in the mountains of southeast Kentucky and has eroded a broad, deep valley before entering the Ohio at Carollton.
