Abrupt textural difference (submitted by John Hollis, Allan Lilly and Bob Jones, UK)

[StephanMantelISRIC]

The definition of an abrupt textural difference has changed slightly from the 2015 version. The latter stated that the change in clay content should occur ‘within < 5cm’. In the latest 2022 version this stipulation has disappeared and the only criteria related to the thickness over which the change should occur appears to be ‘a transitional layer, if present, has a thickness of < 2cm. We do not understand the reasoning behind this change which, in effect reduces the thickness over which it must occur from 5 to 2cm. In our view this difference is trivial, with respect to the importance of the magnitude of the change in clay content.

[StephanMantelISRIC]

Response Cezary Kabala:
As you wrote, in fact the Abrupt Textural Difference must occur within 2 cm. Maybe the wording is not clear, but the previous one has also been questioned... The change from 5 to 2 cm was done to harmonize the meaning of the 'Abrupt TD' with the meaning of the "abrupt" for the distinctness of the layer boundaries, where "abrupt' already means <2 cm (while the transition <5 cm is called 'clear').