  We present an intuitive physical picture for fractures in nacre-type
stratified materials via scaling arguments: strain distributions around a
fracture are rather different depending on directions and size of fractures. We
thus observe that viscoelastic effects are important for parallel fractures.
These effect are taken into account via the simplest viscoelastic model for
weakly cross-linked polymer. Within a certain limit, we find a trumpet crack
shape similar to that in certain polymers and make predictions for the fracture
energy of certain stratified materials in this mode.
