A mysterious shipwreck has finally been identified as a whaler lost more than 160 years ago after scientists analysed tree rings in the rotting timber.
The rings revealed the wreckage off the coast of Argentina to be the remains of the Dolphin, an American whaling ship that sank in 1859 some 10,000 miles from home.
Archaeologists have spent years researching the ship's origin without making a definitive identification.
However, a new analysis of tree rings in its timbers by a team of Argentinian and American researchers, published in the journal Dendrochronologia, may finally have solved the mystery.
Lead author Professor Ignacio Mundo, of Argentina's Laboratory of Dendrochronology and Environmental History, said: "I cannot say with 100 per cent certainty, but analysis of the tree rings indicates it is very likely that this is the ship."
Prof. Mundo and scientists at the Columbia Climate School's Lamont-Doherty Earth Observatory used a huge database of rings from old North American trees to show that the timbers were felled in New England and the south-eastern United States just before the ship was built in 1850.
Other evidence includes artefacts found near the wreck and historical accounts from Argentina and Warren, Rhode Island - the Dolphin's home port.
Co-author Doctor Mukund Rao, a Columbia tree-ring scientist, said: "It's fascinating that people built this ship in a New England town so long ago, and it turned up on the other side of the world."
New England was a major player in the global whaling trade from the mid-1770s until the 1850s.
The industry faded in the 1860s after whale populations were decimated and petroleum came in.
Warren local historian Walter Nebiker believes the Dolphin was built between August and October 1850, of oak and other woods.
Measuring 111 feet long and weighing 325 tons, the Dolphin was launched on November 16, 1850, and Mr Nebiker described her as "probably the fastest square-rigger of all time."
Her last voyage started from Warren on October 2, 1858. The ship ended up off Patagonia a few months later.
A letter to the owners from her master, a Captain Norrie, said she was destroyed when she "lay upon the rocks in the southwestern part of New Bay" - an apparent reference to the Golfo Nuevo, one of Patagonia's few good natural harbours, where whalers were known to anchor.
Shifting sediments revealed the partial remains in 2004 of a wooden vessel in the intertidal flats just off Puerto Madryn.
Researchers discovered that Argentine mariner Luis Piedrabuena had rescued 42 members of the Dolphin's crew.
After processing samples of wood from the wreck in his lab, Dr Mundo turned to Professor Ed Cook, founder of the Lamont-Doherty Tree Ring Lab, a long-time collaborator with South American colleagues, and pioneer in dendroarchaeology, the science of pinpointing the age and provenance of old wooden structures.
Prof Cook utilised the North American Drought Atlas, a massive database whose creation he spearheaded in the early 2000s.
Varying rainfall levels create subtle yearly variations in ring width that allow researchers to chart past climates, date trees' precise years of germination and growth and - in the case of old wooden structures - often where and when trees were cut, since climates vary from place to place, leaving distinct regional signatures.
