Charles Darwin, Bartholomew Sulivan, and the geology of the Falkland Islands: unfinished business from an asymmetric partnership

When in 1846 Charles Darwin published the first account of the geology of the Falkland Islands he drew on his experiences in 1833 and 1834 during the voyage of Beagle, and on collections made at that time by the ship's Assistant Surgeon, William Kent. Aboard HMS Beagle Darwin struck up a particular friendship with Lieutenant Bartholomew Sulivan who subsequently revisited the Falklands between 1838 and 1845 in command of HMS Arrow and HMS Philomel. The surviving letters that Sulivan wrote to Darwin during those voyages contain a wealth of additional geological observations. Sulivan also dispatched additional geological specimens to Darwin, one of which can be identified in the extant Beagle collection. Darwin utilised some of Sulivan's structural geology sketches in his 1846 paper, but otherwise the detailed and accurate observations were only partly and ambiguously recorded there in a footnote. Sulivan described fold and cleavage relationships, made the first record of intrusive dolerite dykes in the Falkland Islands, and recorded landforms and lithologies that could have led to the early recognition of both Quaternary and Late Palaeozoic glaciation in the Falklands. Glacial phenomena were not generally understood at the time and Darwin at first misinterpreted some of Sulivan's prescient observations. The acknowledgements in Darwin's 1846 paper do scant justice to Sulivan's contributions which, as a result, have remained generally unappreciated. This paper seeks to rectify this situation whilst reconciling Darwin's account with the modern geological interpretation and reviewing his specimen collections in current terms.