Rock layers are also called strata (the plural form of the Latin word stratum), and stratigraphy is the science of strata. Stratigraphy deals with all the characteristics of layered rocks; it includes the study of how these rocks relate to time. The break would be caused due to old age and the sturdiness of the rock. if the rock is extremely old (has a lot of layers) it’s more likely to slowly crack due to old age and the piling of layers.