Walther’s law of correlation of faciesThe principle that faciesthat occur in conformablevertical successions ofstrata also occur in laterallyadjacent environments.[A vertical progression offacies can be foundcorresponding lateral facieschanges]
Walther’s Principle < vertical and horizontal facies match >The various deposits of the same facies-area andsimilarly the sum of the rocks of different facies-areas are formed beside each other in space,though in a cross section we see them lying on topof each other.As with biotypes, it is a basic statement of farreaching significance that only those facies andfacies-areas can be superimposed primarily whichcan be observed beside each other at the presenttime.
Walther’s Law• Sedimentary rock types record the environment of their deposition.• Depositional environments can shift laterally as conditions change.• When so, laterally related environments become superimposed.• Time-transgressive sedimentary formations, are the result.• The vertical succession and lateral sequence of facies will be the same.
Walther’s Law• Certain facies associations are common in the rock record.• For example, most clastic shoreline show a series of depositional environments that are progressively finer-grained in the offshore direction.• There are facies belts of coarses sands, and silts and clays. If the relative sea level changes, deposits of these facies belts accumulate.• Three facies pattern are possible.
Walther’s LawFacies belts could pile up vertically if the relative rate of sea-level rise is exactly balanced by the sedimentary output of the land.
Walther’s LawFacies show a transgressive pattern when the sediment supply is overpower by a relative rise in sea level, or when the land subsides tectonically. Both cause the shoreline to move landward
Walther’s Law Facies show a regression pattern when the shoreline moves seaward due to an excess sediment supply from land, when the land is tectonically uplifted and the sea level retreats, or when there is a relative lowering of sea level.
Walther’s Law Exceptions• The law is invalid where the contact between different lithologies is non-conformable (due to lack of deposition), or during cases of rapid environmental change when non-adjacent environments may replace one another.