This is Roald Tweet on Rock Island.
I am sorry to report that the Guinness Book of World Records has just rejected an application to list the Upper Mississippi River Valley as the world's largest mural.
The application was perfectly legitimate. The mural in question was formed creatively over thousands of years by the Mississippi River. Millions of years ago, much of the Midwest was covered by an inland sea. Crustaceans living in the sea deposited layer upon layer of shells on the seafloor. The layers turned into limestone. Other conditions produced sedimentary layers of shale, sandstone, coal, and clay.
By the time the Mississippi arrived, there were 27 such layers, each different, named for where they appear along the Mississippi: the Dubuque Formation, the Galena Limestone, Decorah Shale, St. Peter Sandstone, Shakopee Dolomite. The Palisades at Savannah reveal the Racine formation. The island of Rock Island is made of the Wapsipinicon layer. The river cut a channel down through these layers from the Falls of St. Anthony to Burlington, Iowa, forming cliffs, bluffs, and palisades. These layers appear because the formations tilt an average of ten degrees to the southwest. The land often twists in other directions as well.
The result is a grand 500-foot-high mural some three hundred miles long on both sides of the Mississippi. Its ribbons of muted colors—the blue-gray limestone weathering to a buff yellow as the bits of iron oxidize, the gray shale, red clays and sandstones—tell the geological and biological story of that ancient lake and the swamps which followed to anyone who travels the river or the great river road beneath the bluffs. Also apparent is the work of the river itself, wearing away weak spots, seeping into caves and crevasses, sculpting natural monuments with names like Sugar Loaf and Half Dome.
All the other murals in the world would fit in less than one mile of ours, but the Guinness folks said no. Even their large imagination was no match for the Mississippi. In order to qualify, the said, a mural must have been done by an artist.
But of course, the Mississippi Mural was.
Rock Island Lines is underwritten by the Illinois Arts Council, a state agency, and Augustana College, Rock Island.
