Wallula Gap is famous as the constriction where the massive ice age floods (a.k.a. the Missoula floods) were temporarily delayed on their journey to the Pacific Ocean. At Wallula, the Columbia becomes narrower, hemmed in by steep lava cliffs.
The right hemisphere, which functions as the noncritical, holistic, nonverbal and pattern-oriented component of the brain appears to accept what the left hemisphere passes to it without question.