1. Walther’s law of correlation of facies
The principle that facies
that occur in conformable
vertical successions of
strata also occur in laterally
adjacent environments.
[A vertical progression of
facies can be found
corresponding lateral facies
changes]
2. Walther’s Principle
< vertical and horizontal facies match >
The various deposits of the same facies-area and
similarly 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 top
of each other.
As with biotypes, it is a basic statement of far
reaching significance that only those facies and
facies-areas can be superimposed primarily which
can be observed beside each other at the present
time.
3. 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.
4.
5. 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.
6. Walther’s Law
Facies belts could pile up vertically if the
relative rate of sea-level rise is exactly
balanced by the sedimentary output of the
land.
7. Walther’s Law
Facies 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
8. 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.
9. 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.