A model of the way ice deforms based on experiments on blocks of ice conducted in the early 1950s by J. W. Glen and adapted by J. F. Nye to apply to glaciers. Glen found that the strain rate in a block of ice subjected to constant stress reaches a steady value. In glaciers, the relationship between strain rate (e) and effective shear stress (τ) is given by e = Aτn, where A is a constant related to temperature and n is an exponent with a mean value of approximately 3.