Walther's law

1. n. [Reservoir Characterization]
A law stating that lithologies that conformably overlie one another must have accumulated in adjacent depositional environments. Exceptions occur where there are erosional breaks. This law allows for transformations from the vertical data to a horizontal set and is often used when a vertical sequence of facies has been identified and characterized (for example, with Markov chain analysis) to estimate the horizontal depositional pattern.