They are the evidence of a dark episode in recent Scottish history that saw children who had already been robbed of their lives then robbed of their identities.
It is estimated that the bodies of as many as 100 children lie unmarked and unmourned in St Mary’s - all of them former residents of the town’s notorious Smyllum orphanage.
The Catholic nuns who ran the institution until it shut in the 1980s already stand accused of terrorising the living in their care.
Now it has been revealed how children who died during Smyllum’s century in existence were placed without ceremony in paupers’ graves at nearby St Mary’s and no record kept of their final resting place.
Survivors of the home, many of them still struggling with their own horrific experiences of abuse, are now determined to honour the children who never left.
They are campaigning for the Catholic Church to fund a proper memorial and properly examine records so the dead can finally be given back their identities.
Frank Docherty, 59, survived two years of beating and humiliation at Smyllum after his alcoholic parents decided they could no longer look after him and his siblings and dumped them in the care of the Catholic Church in 1954.
Docherty told Scotland on Sunday that when children died from diseases none of the nuns would speak about it. He never recalls attending a requiem mass for any of the orphans.
In stark contrast, he recollects vividly having to kiss the forehead of a dead nun as she lay at the entrance to St Mary’s Church in Lanark at the start of a requiem mass before burial at St Mary’s Cemetery.
The part of the cemetery reserved for nuns and priests contained rows of crosses and headstones. Tiny mounds of earth are all that mark the existence of the dead orphans.
There are few, if any, clues to when the children died, how they died, and whether their deaths were investigated and recorded within the requirements of the law.
"The nuns were a law unto themselves at Smyllum," said Docherty. "I fear that years ago many of these children were buried without proper records being kept of who they were."
Docherty said that on his first day at the orphanage a nun reacted to his crying by beating him with a hairbrush and repeatedly kicking him. Worse was to follow, but his main preoccupation was with those who didn’t survive.
He said: "It’s nothing short of criminal to leave so many dead children abandoned in this way. What hope is there of any relative trying to find a loved one? What are they supposed to do? Pray beside any old mound in the ground? That’s truly unholy and an insult to the little ones’ memories."
At present, the only memorial to the children is a stone engraved with the words: "Sweet Jesus have mercy on the souls of the children of Smyllum."
Docherty and his fellow campaigners at In Care Abuse Survivors (INCAS) claim the Church has obstructed their efforts to identify and remember the children, by erecting a wall of red tape.
Church officials, according to Docherty, say it is now too difficult to research the identities.
INCAS secretary, Jim Kane, of Forth, Lanarkshire, said: "These children had names, had friends, and some had relatives. No one knows when they died or who they are because they’ve been completely forgotten.
"It’s a pitifully sad sight to see so many little humps and indentations in the grass that are the only indications of their last resting places.
"It’s bad enough that adults have come forward to tell of the cruel regime at Smyllum. But to leave these children’s graves unmarked is just as big a sin."
Kane says he is one of several orphans who were physically, psychologically and spiritually abused at the hands of the nuns at Smyllum.
He said he was facing an uphill struggle against Catholic Church officials who hold records of the names of the orphans who died between 1864 until Smyllum closed in the 1980s.
Kane said there was no suggestion that any of the children had died other than from natural causes.
He added: "I estimate there are up to 100 orphaned children’s graves in the cemetery. There are scores of indentations where burials have obviously taken place over many years.
"I contacted the Sisters of Charity for help and was very disappointed to be told by their principal archivist that they had absolutely no record of the dead children’s names.
"I was told to contact officials at St Mary’s Church in Lanark, but every time I’ve tried to make an appointment to discuss this I’ve been fobbed off. I was originally told I would have to provide names and dates of the children who died before parish records could be checked. That’s impossible because I don’t have their names.
"Now I’ve been told I’ll have to wait until someone at St Mary’s has time to provide a list of orphans buried in the cemetery then send those details to London where, hopefully, the information will be sent to me."
Smyllum was sold off in the 1990s and the building and grounds used to build flats and houses. The profits the Catholic Church made in the sell-off only exacerbate the sense of injustice among the Smyllum survivors.
Kane, 62, said: "INCAS and many local people want the Church to pay for a new memorial.
"The Church could use some of the wealth it gained in selling Smyllum itself for the development of flats, as well as selling off other land in the town for housing."
A spokesman for the Catholic Church in Glasgow denied that it had been "insensitive" about the children’s graveyard and requests for a new memorial.
The spokesman added: "I will speak to the Motherwell diocese to find out what can be done to speed up finding the children’s names, though I expect it will be a difficult task.
"It may be that if they were not originally from the Lanark parish their records may be elsewhere. I will also pass on the INCAS request for funding for any future memorial."
Hundreds of former residents of children’s homes run by the Catholic Church in Scotland, including Smyllum, are involved in an ongoing legal case for compensation for the alleged abuse they suffered.
Last year, Scotland on Sunday revealed how a former resident of Nazareth House children’s home, Kilmarnock, claimed she was raped by a priest.