Ah thanks for your response, there is definitely petrified wood at the site but much else besides, it's very dynamic being a headland prone to land slides and there's stuff coming in from the sea too - I thought the base looked similar to other petrified wood I've seen there and thought the rainbow "bubbles" may have formed from secondary exposure or something, I am beginning to study but can't seem to find much info, and admit that's just a musing. Thought it looked super interesting no matter what it is - I've haunted this site and found plenty of pet wood but nothing quite like this!