This is from the 1976 USGS topographic map, with the principal parts of a daisy wheel superimposed in green. The center is the intersection of Maple Street and Arkansas Avenue, at the northeast corner of the University campus. North-south is an ever-widening transportation and service corridor, northeast-southwest is a ridgeline/watershed that follows a near-perfect sine curve through the center of Fayetteville. The brown area indicates the watershed, watercourses are blue. Gulley Park is in the upper right corner, bounded in red.
The White River gathers it’s tributaries from the north slope of the Boston Mountain and the south and east half of Fayetteville, flowing north into Beaver Lake, and eventually into the Mississippi River, nearly but not quite merging with the Arkansas River. The Illinois River also originates on the Boston Mountain, draining the north and west half of Fayetteville’s watershed, then turning south and passing through Oklahoma on its way to the Arkansas River. The two river systems are separated by a ridgeline that runs from Mt. Kessler to the Boston Mountain. The gap in the mountain to the southwest of Fayetteville (hwy. 62 corridor) was eroded by water, as was all the surrounding Ozark terrain.
I haven’t made this up, this is the landform that we live on. Go to a USGS topographic map, look at the relative size of the floodplains of the two rivers, at the subtle differences in elevation. A land formation that was created almost entirely by erosion; with one significant fault line running north-northeast, just east of the center of this circle. My theory is that at some point the fault shifted, lowering the terrain to the east; thus capturing the flow of the West Fork (and possibly the Middle Fork) from the Illinois River. When that might have happened is anybody’s guess, but it could have been as recent as 1812.