Last crossing

Kate pulls the canoe across the pressure crack in the middle of the lake.  As you see in some of the other photos, these cracks are very beautiful. The ice shrinks and pulls apart, then the water in the cracks freezes, and the pressure builds again as the ice expands. 

Sometimes that expansion causes pressure enough to make the ice buckle.  It rises on one side of the crack, and dips on the other side.  And these up and down places ripple along the crack. The ice that gets pushed down melts faster, sometimes creating large pools of water surrounded by thick ice.