Found on long walk to blow away the boxing day cobwebs, tucked away and not fully legible. I wonder if the full text is written about somewhere?
Who planned upon this mountain's rock to build
High o'er the shifting sands of Mawddach's flood
They knew the soul of man had need of food
From Heaven and that the world's Creator willed
That from far hidden deeps should hearts be thrilled
With touch of ocean's wild infinitude.
They drank the dews of morning as they stood
And with the sunset's latest awe were filled.
?? 30th 1891 HDR
Filled in missing words that I couldn't read from this blog post https://salsin.zenfolio.com/blog/2014/4/the-ashes
Update 29th Dec 2018:
I had the initials as HDB but then got comment from Ceridwen, which made me look again and it does look more like HDR for Hardwicke Drummond Rawnsley
That then led me to this other photo of the engraving and confirmation of all of the words: https://compubooks1blog.wordpress.com/2013/08/15/mawddach-poem-1891-by-canon-rawnsley-noels-father-engraved-in-rock/
And from the 2013 photo it seems that the date is October 30th 1891.
It is interesting, since the place it is is the first piece of land that was acquired by the National Trust in 1895 donated by Fanny Talbot a friend of Octavia Hill and Canon Hardwicke Rawnsley, two of the National Trust's founders - see: https://www.nationaltrust.org.uk/south-snowdonia/features/our-beginnings-at-dinas-oleu
But presumably the matter was talked about quite a few years earlier than the formality in 1895.