while fast ice is relatively stable (because it is attached to the shoreline or the seabed), drift (or pack) ice undergoes relatively complex deformation processes that ultimately give rise to sea ice's typically wide variety of landscapes. wind is thought to be the main driving force along with ocean currents. the coriolis force and sea ice surface tilt have also been invoked. these driving forces induce a state of stress within the drift ice zone. an ice floe converging toward another and pushing against it will generate a state of "compression" at the boundary between both. the ice cover may also undergo a state of "tension", resulting in divergence and fissure opening. if two floes drift sideways past each other while remaining in contact, this will create a state of "shear".