Counting tree rings on the beach

This large, partly-burnt stump on the beach at the Merthyr Mawr end posed a challenge. The tree rings were very obvious but very far apart. The question is then whether the sea has eroded some of the intervening rings. Wide rings would be evidence of strong growth. I think that means good climate. I had a go at counting what I could see and estimate that 100 years would be a reasonable age if the rings are true. The other way of estimating the age is by girth. This source suggests a 100 year old tree might have a girth of 3m. It does give some provisos. 3m girth would mean a diameter of about 1m which is probably not far off given the burnt section. It suggests that no rings are missing.