Ductile behavior in rocks is often associated with plasticity due to dislocation motion or diffusion under high pressures and temperatures. However, ductile behavior can also occur in brittle materials. We consider a damage-based rheology for ductile behavior of the upper brittle crust. Damage has been used to describe inelastic behavior of solids in engineering, and covers a wide range of phenomena from microfracture in brittle materials to dislocation creep in the mantle. We apply continuum damage to describe the inelastic behavior of brittle materials and the temporal and spatial changes in rheology. We use this empirical method to simulate the bending of brittle layers under a constant bending moment and the flexure of a plate under a constant load. We introduce a yield stress below which damage does not occur. A damage variable α represents the degree of damage in the brittle material. Where α = 0 there is no damage, and where α = 1, failure occurs. We calculate quasi-elastostatic solutions and use the stresses and strains obtained from these solutions to obtain the damage rate dα/dt, which is proportional to powers of the excess stress and strain over the yield values. We investigate a wide range of behavior from slow relaxation to instantaneous failure. We obtain perfectly plastic behavior in brittle materials and develop fold hinges through damage mechanics. Thus continuum damage mechanics can be used to simulate ductile rheology in brittle materials analogous to folding due to cataclastic flow in the elastico-frictional regime.