Why might a single rock layer exhibit different types of sedimentary rocks within it? View Available Hint (s) Why might a single rock layer exhibit different types of sedimentary rocks within it? Such a rock layer, termed a facies, when traced laterally represents a variety of depositional environments that formed in a sequence over time. Such a rock layer, termed a facies, when traced laterally represents a single depositional environment that formed over time. Such a rock layer, termed a facies, when traced vertically represents a variety of depositional environments that formed at the same time across a broad area. Such a rock layer, termed a facies, when traced laterally represents a variety of depositional environments that formed at the same time across a broad area. Such a rock layer, termed a facies, when traced vertically represents a variety of depositional environments that formed in a sequence over time.