29 July 1977: first scenes of Image of the Fendahl (1977) as the hiker meets his doom and the scientists play with their pet skull. (Will give reasons for this dating on Saturday.)
date of real event, almost but not quite specified in canon
29 July 1890: death of Vincent van Gogh
Further south, I think – there’s a feel of Ken Campbell’s Wol Wontok about it. Somewhere near the Philippines, perhaps?