” - - - The biggest obstacle is jagged rocks jutting up from the bottom of the Mississippi which make it impossible for barges to move. - - - “
BULL PUCKEY! The only “jagged” rocks are where a.) the gradient of the Mississippi is steep enough to generate white-water rapids, or b.) The bank-stabilizing efforts of the US Corps of Engineers has added rip-rap to the banks.
IOW, in the sections of the Mississippi that are used by barges, the most likely “jagged” object is a rusty metal car, truck, air conditioner, freezer, refrigerator, you know the 99.9% of the stuff taken off EVERY YEAR from the bottom of The Father of Waters.
Old bridge pilings/debris might be out there, too. I know some of the older bridges over the upper Missouri River were dynamited after replacements were built.The same practice may have been used on the Mississippi.