Closure was achieved on Grosse Ile. After years of Famine studies, visiting the former quarantine island in Quebec was for me a searing experience. More than 5,000 Irish emigrants were buried there during a fever epidemic in 1847.

This most important Famine memorial outside Ireland is maintained today by the Canadian Parks Service - due partly to the dedication of people such as Marianna O'Gallagher, Quebec historian and author. Ms O'Gallagher, who has shown our two women Presidents around the island, arranged for The Irish Times to take a Parks Canada ferry one morning at Montmagny. Thousands of geese preparing to migrate southwards added to the atmosphere during a 40-minute trip on the St Lawrence.

In 1847, as the panic-driven exodus from Ireland got under way, some 20,000 emigrants perished on this route. The vessels which brought the first wave of Famine refugees across the Atlantic have been described as "pigsties", "floating lazarettos" and, most symbolically, "coffin ships".

The poorest took the cheaper route to British North America. They were crammed into ships designed for transporting lumber, without proper air, water or sanitation. Already weakened by malnutrition before embarkation, disease and death made terrible inroads during the voyages, which lasted up to 45 days. On some ships almost a third of the passengers died. Black '47 was by far the worst year in this respect, with the mortality rate among Irish emigrants to Canada reaching 17 per cent. As conditions improved, it fell to 1 per cent the following year.

The latest Canadian research puts the number of deaths among emigrants arriving through Quebec in 1847 at 17,477; of those, 5,293 perished on board ship, either during the crossing or in quarantine; 3,452 died in the fever sheds on Grosse Ile; the remaining deaths occurred as immigrants, released after cursory medical inspection, carried disease to Canadian townships. Emigration through New Brunswick followed the same calamitous course on a smaller scale, with 2,000 deaths recorded.

At Grosse Ile the authorities were overwhelmed by the scale of the influx. Typhus spread quickly to epidemic proportions, despite outstanding humanitarian efforts. The Cork and Liverpool passengers were "halfdead from starvation and want before embarking", according to the medical superintendent, Dr George Douglas.

By May, more than 12,000 emigrants were detained at Grosse Ile. Dr Douglas considered it physically impossible to quarantine them on the small island. His decision that healthy passengers be quarantined on board the line of vessels awaiting disembarkation contributed to the disaster. A fatal delay of several days occurred before fever victims were removed. Infection enveloped the emigrants as healthy and ill, dying and dead were confined in the fetid holds.

One of the priests tending the sick, Father Bernard O'Reilly, said it was unacceptable that thousands of his fellow countrymen should be sacrificed through neglect and lack of foresight. Father Edward Horan observed that, "seeing the gauntness of most of these poor people, we can assume that lack of food is the main source of their sickness".

Ashore, with 2,000 sick crowded together, the situation verged on anarchy. A French-Canadian priest described conditions: "Beside each tent lies fermenting waste which nobody has had time to carry away, and inside, in two and sometimes three rows, lie living skeletons; with hardly enough straw on which to stretch out their limbs, men, women and children, pell-mell; and so close together that one could hardly take a step without treading on some part of the breathing mass. Nearly all are suffering from dysentery as well as from fever, and are too weak to drag themselves outdoors, and hence must wallow in their own filth."

Under the July sun the heat was suffocating, while at night a north wind chilled the sick. In the sheds, "the infectious air is thick with a fetid stink that would rattle the head of the strongest". The priest heard "a song of death, a savage bellow" from a woman driven insane by the loss of her husband and children.

ThE shipping of the destitute and diseased continued until perilously late in the season. Lord Palmerston, the British Foreign Secretary, had chartered nine ships to clear his Sligo estates of 2,000 tenants. One of those, the Lord Ashbur- ton, was the last vessel to be inspected at Grosse Ile in the 1847 navigation season. The Quebec Gazette said its condition was a disgrace to the home authorities: 107 passengers had died during the crossing and another 60 were ravaged by fever.

A 40 ft granite Celtic cross dominates Grosse Ile. Designed by Ms O'Gallagher's grandfather, it was erected by the American Ancient Order of Hibernians in 1909. The cross has inscriptions in Irish, English and French. The French version recalls that "thousands finished their sorrowful pilgrimage consoled and fortified by Canadian priests" (four Roman Catholic and two Anglican priests died during the fever epidemic).

A monument unveiled last August commemorates the 7,553 immigrants of every nationality buried on the island. "The memorial sculpts the landscape just as recollections shape memory." Names are inscribed on glass panels, with space left for the 1,545 "unknown but not forgotten". Sheets of iron symbolise vessels sailing westward.

Most evocative for this pilgrim, however, was the memorial to four doctors who died of typhus contracted in the summer of 1847. On a side of the marble column is written: "In this secluded spot lie the mortal remains of 5,424 persons who, flying from Pestilence and Famine in Ireland, found in America but a grave." The trenches dug for mass graves were still clearly visible, as the wind covered them with the golden foliage of another Canadian autumn.

The French-Canadian priest wrote in the autumn of 1847: "The dying gasps of agony, the cries of despair and the shrieks of madness have been succeeded by the silence of the tomb. Around the funereal fields the voice of man is quelled."

While Grosse Ile was a quarantine station from 1832 to 1937, in Quebec it evokes the recollection of les immigrants irlandais. Besides remembering the Famine tragedy, it illustrates the drama of immigration. Among the exhibits is a disinfection unit opened in 1892. Each immigrant was showered and had his clothes disinfected. The unit was considered so advanced that Ellis Island officials came up from New York to inspect it.

An Anglican nun, Sister Anna, who worked in Belfast, described Grosse Ile as holy ground after a visit in 1993: "Here men, women and children in the thousands lie buried. They have at last found peace, having suffered beyond all measure and died appallingly. We can still find peace and even joy on Grosse Ile but only if we discover it as a holy place, a memorial where the last drops of bitterness are washed away."

Brendan O Cathaoir's Famine Diary will be published this month