It has been 100 years since Barrell (1917) solidified the base level concept, which is widely used in sequence stratigraphy. The concept was first introduced by Powel (1875). It is still broadly used in non-marine, near shore and deep-water settings. The problem arrives when the base level concept is applied in deep-water settings. Most of us will consider the sea level/wave base as a base level. However, it is simply not! The magnitude at which sea level or wave base varies is much smaller than the changes that we observe on the modern or ancient sea floor. Recalling, below the base level deposition happens and above it erosion is possible. This original definition gets violated when sea level is chosen as a base level proxy. As annotated in the figure below, the sea level or wave base can not be considered as a proxy for the base level since erosion and deposition happen below this level. To solve such a conceptual problem, we always need to place the base level close to the sea ...
Open discussion for fun!