The piano part of Movement IV of Crossing Rivers IV requires the pianist to play white-key note clusters with the palms of the hand and black-key note clusters with completely flat fingers (no tips). This is indicated at the beginning of the movement over the first four clusters. Black-key and white-key clusters are clearly indicated in the score by the placement of sharps or flats next to every note within a given cluster, or by placing no sharps or flats next to others. Stasack has mentioned that one need not hit the exact notes indicated in the score, but the important thing, according to her, is to follow the shape and dynamics of each short phrase, as well as the general range on the keyboard of each cluster. The hand is flat in shape and makes a crawling motion up or down the keyboard, following the direction of each phrase. In order for there to be legato connection between each cluster, the hand needs to be flexible.