150-year mystery of lost expedition may be solved: A chance find by a man on holiday may explain an Arctic disaster, reports James Buchan

In Baffin's Bay where the whale-fishes blow, / The fate of Franklin no man may know

Canadian archaeologists are preparing an expedition to a remote Arctic island this summer, partly to examine two large mounds that may hold the answer to the greatest of all polar mysteries: the fate of the Franklin Expedition of 1845.

A team from the Prince of Wales Northern Heritage Center at Yellowknife in the Northwest Territories intends to use ground-penetrating radar to make computer images of the mounds, on the north-western tip of King William Island. Dr Charles Arnold, director of the centre, said last week: 'It should indicate if they are natural or have been built.'

Two Royal Navy vessels, the Terror and the Erebus, with 134 men commanded by Sir John Franklin, sailed from the Thames on 19 May 1845 to seek the Northwest Passage, an Arctic route to the East Indies. The ships were last seen at the entrance to Lancaster Sound on 26 July. Fifteen expeditions, several equipped and financed by Lady Franklin, were sent to search for them. But no survivors or remains were found. The mystery haunted an entire generation, including Dickens and Tennyson, and inspired the folk-song 'Lord Franklin', quoted above.

The mounds were discovered last July by a Royal Navy recruiting officer, Lt Ernie Coleman, during a holiday on King William Island. Measuring 100ft long and 60ft feet wide, they are made of earth and rise about 15ft above the flat of the island.

Geomorphologists say they may be 'pingoes', hummocks created naturally by upheaval in the Arctic permafrost. But Lt Coleman, 50, said: 'They're entirely alien to their surroundings. There's nothing like them in the whole Arctic.'

The mounds are just inland of the nearest landfall from the point where, according to a note found in a cairn on the island in 1859, the Terror and Erebus became stuck in ice in September 1846. They are aligned on a precise north-south axis. Lt Coleman believes they were built in the summer of 1847 to cover the dead of each vessel.

On one of the mounds are two scars, marked with what appears to be a pattern of rocks, where he believes bodies or expedition documents - even its cameras and plates - may have been buried.

'We may be on the verge of one of the most important finds in polar history,' said Pia Casarini, who is writing a dissertation on Lady Franklin at the Scott Polar Research Institute in Cambridge.

The cairn where the note was discovered was south of the mound site. The note, found by officers of the Fox, a yacht rigged out by Lady Franklin in a last effort to learn her husband's fate, is now in the National Maritime Museum in Greenwich. It is dated 28 May 1847 and ends 'All Well'. Scrawled in the margin are a few lines, dated 25 April 1848, saying that the ships had been abandoned in the ice, that 105 survivors were setting off overland to the south, and that Sir John had died on 11 June 1847 - barely three weeks after the 'All Well'. This sudden collapse of the expedition has haunted 150 years of research.

In 1984, Professor Owen Beattie, a forensic anthropologist at the University of Alberta, exhumed the bodies of three sailors from the expedition, which had been buried at Beechey Island in the winter of 1845-46. He found high levels of lead in their bones and proposed the controversial theory that the expedition had been poisoned by lead solder in their canned provisions.

This July's expedition will make a detailed survey of all the cairns on King William Island, and will also examine a group of skulls, bones and metal discovered last summer. If the mystery is ever to be solved it could be this summer.