This is Roald Tweet on Rock Island.
Two great rivers flow past Rock Island on their way to the Gulf of Mexico. One of these has a name, the Upper Mississippi. Storied, mythic, shining. Native Americans traveled this river ten thousand years ago, followed by explorers, trappers, missionaries, by Mark Twain, by steamboats and tourists, by barges of corn and soybeans.
Had the waters of the Mississippi been clear, these generations of travelers could have watched another river below the surface, a dark river of sand, the Mississippi's alter ego, moving in a current slower than the water up above.
One river is fed by rain, the other by ancient deposits of sand left near St. Paul by the glaciers during the ice age. Like twins with opposite personalities, these two rivers bicker and fight.
The Mississippi wants to flow, the sand says "stay." The water wants to turn left, the dark river says "no."
In this dance, the water sometimes wins, sometimes the sand. In September and October when the Mississippi is low, the sand pushes up islands and sandbars or fills in side channels, choking the water, sometimes forcing it into such new channels that Illinoisans would wake up and find themselves in Missouri. In spring when the water is high, the current washes the sand away, sending it down stream to new adventures. During floods, many levees made of sand melt and give under the push of the water.
In the 19th century, it was this sandy river beneath the water that stopped boat traffic or changed the channel so that steamboats wrecked and sank. The sand made every steamboat pilot memorize the river and pay attention to the subtle signs the sand sends to the surface. The sand built townsites beneath the bluffs, the river often washed them away. Prehistoric Indian civilizations, some eight layers deep, lie beneath the relentless sand.
Today, the dance of the water and the sand is quieted by the locks and dams that keep both rivers in their place. We have almost forgotten the dark river. But it's there, beneath the water, waiting.
Rock Island Lines with Roald Tweet is underwritten by Augustana College, Rock Island, Illinois.
