The submerged forest time sequence

Click to enlarge.

This table, assembled from multiple sources, suggests how the submerged forest around the West Wales coast  relates to sea-level changes, climatic and vegetation changes and variations in sedimentation.  

It is suggested that during the time of rapid marine transgression (1.4m per century) eustatic sea level rise was faster than the residual rate of isostatic rebound.  During the "submerged forest growth period" (approx 7,000 - 4,600 yrs BP) the rate of isostatic rebound was temporarily faster than the rate of eustatic sea-level rise (between 4 and 8 cm per century), causing a shoreline retreat.  After that, the rate of sea-level rise was slightly faster........

The 7 ka eustatic event was the "switch" which made the growth of the forest possible in what is now the intertidal zone.

https://brian-mountainman.blogspot.com/2020/03/the-7000-bp-eustatic-event.html