Mile 616.0 - Knowlton Crevasse

RBD 616 Knowlton Crevasse

The Mississippi River broke the levee here on the Arkansas side in 1912 and then again during the great flood of 1927 and a blue hole survives as reminder to the power of water overtopping an obstruction. A blue hole can be created anywhere flowing water is made to climb over something and roll down the other side, such as a pile of heavy driftwood, or a wrecked barge, or a dike or a pile of rip-rap -- or by the levee itself as it did at Mound's Crevasse (1927) and here at Knowlton. As it comes rolling down the other side it falls and digs in deep into the mud & sand and scoops it all out. After the water level recedes a hole is left behind which clears out with blue water. At Knowlton the blue hole created a small oxbow shaped lake, probably in the shape of the levee at the time. 2,000 people were left homeless in this area in 1927 and at least 18 perished before the waters finally drained away.

Today there is a high bluff of big-grained creamy yellow sand and gravel piled up between the river and the oxbow blue hole. Its the highest ground in the region, not going under water until well above flood stage, which means it was created in a much higher water event, most likely by the flood of 1927 itself. (Note: the flood of 2011 submerged everything between the levees along this entire section of river). You won't want to camp here, because its private property and there is frequent travel & hunting due to easy land access from the nearby Arkansas levee for 4WD. Regardless its an interesting place to stop and get a view of the river from a high place. This used to be the best rock-hounding in the area but recent high waters have been submerging the gravel bars in sand. In the past twenty years we've seen conch fossils, bison antiquus bones, other mega-fauna long bones, chrinoids, geods, coral, and rocks of origin from everywhere upstream such as Rocky Mountain marble, Great Plains granites and Appalachian shales -- as well as strange globs of petrified river mud (not found anywhere else but the Lower Mississippi Valley). This gravel bar used to extend from the Knowlton high point mile 617 all the way down to the top end of Island 69, but in recent years the gravel has been disappearing.