shifting (
http://definr.com/shifting)
adj 1: continuously moving or changing from position or direction;
"he drifted into the shifting crowd"; "their nervous
shifting glances"
2: continuously varying; "taffeta with shifting colors"
3: (of soil) unstable; "shifting sands"; "unfirm earth" [syn:
unfirm]
n : the act of moving from one place to another; "his constant
shifting disrupted the class" [syn:
shift]