The three telephoto photographs taken from by the river show Jabz Cave. As is shown by the photograph taken from above, it is not a cave, but a gap in the edge. A dry stone wall has been built in it to form a lookout place. The centre photograph shows the seat.
There is a splendid view from here over the villages of Grinton and Reeth and on up Swaledale.
Jabz lived in nearby Reeth village in the cottage now known as Raisbeck, which is shown above right. He used to come up to Fremington Edge, so I'm told, to write poetry.

The OS map labels 'Jabz cave', but he is listed, with more information in the Bulmer's Directory of 1890 on the GENUKI site, © Colin Hinson, (scroll down to Reeth Grocers and shopkeepers). It lists him as Raisbeck Jabez, a Reeth shopkeeper, printer, stationer, bookseller and Darlington and Stockton Times agent.

I will be grateful for any more information about him.