Rock layers are the different layers of sedimentary rocks that have been formed over time. Seams, which is a five letter word, refer to the cracks or breaks in the rock layers. STRATA, which is a six letter word, refer to the layers of sedimentary rocks that have been formed over time. Folia, which is a five letter word, refer to the thin layers of sedimentary rocks that have been formed due to the pressure of the overlying rocks.