Frost wedges in the Arctic can be several meters wide, but they are built incrementally. The annual cracks that fill in with water in the thaw, which subsequently freezes to grow the wedge, are much less wide. Consider a site in which the current frost wedges are 2.5 m wide, the minimum annual temperature is -30°C, and the mean frost wedge polygon diameter (hence spacing between ice wedges) is 20 m. If the coefficient of thermal expansion is 1x10^-5/°C, how wide will the resulting contraction crack be? How old is the frost wedge?