IT IS DARK in the shed. Stacked on shelves in the half-light are boxes filled with bits of bones teeth, broken delph, pottery, blades, nails. Beth Cassidy gingerly lifts a dirty, mud-clogged, plastic bag out of one cardboard box.

She holds it aloft, relishing the chilling effect of its contents - a human skull.

"You can recreate instances in time which allow you to reach back and pull actual events from the past into the present," she says.

"That split second in time, we could recover that. Everything we recover tells us something."

Archeologists are detectives, she explains - detectives with a deep appreciation of events and moments that have usually remained buried and forgotten for centuries.

This dig on Church Street in Dublin - the site of new offices - has been carried out by Cassidy's company, Archeological Development Services. The next step is to catalogue all the material that has been uncovered in order to produce an excavation report.

The remains of 12 young adults and children have been found, dating back to early-medieval dimes. "We are respectful of what we are dealing with," Cassidy explains pointing out, however that archeologists cannot allow themselves to be superstitious.

The tools of her trade include mattocks, shovels, pickaxes, garden implements and wheelbarrows. "We don't go out with teaspoons," she laughs. "We use builders' tools."

Her interest in archaeology stems from the combined influences of her parents. "My mother had an influence because she was a keen historian, and my father was a very practical man," she says.

AFTER SECONDARY school at the Daughters of the Cross in Donaghmore Co Tyrone, she went to Queen's University Belfast to study archaeology. She later specialised in environmental archaeology, working with Dr Chris Lynn.

Her face lights up as she recalls one of her most thrilling finds while she was still a student, working in Armagh city on a dig in 1980, when she uncovered "wee tiny needles".

They were "very tiny glass rods twists of coloured glass", she explains, which had been used for chalices to give the impression of built-in jewels.

"I'd found the tools of the trade from an early-Christian period. It really is little needles in a haystack sometimes." In 1988 she moved to Dublin. The following year she set up Archeological Development Services with her colleague, Eoin Halpin. The company employs 12 full-time staff as well as a further 30 to 40 people who are on contract.

With so many apartment, office and retail developments taking place in old parts of the city, her firm provides developers with the means to carry out the archaeological investigations required by planning law before building begins.

It offers developers a range of services, including the management of all aspects of archaeological work, archaeological monitoring, excavation and post-excavation and artefact and ecofact analysis.

Her own main involvement today is not so much at the dig but at the management side of the business.

"Our main concern is to record and retrieve traces of our past which are going to be removed." The archaeologist's job, she explains, does not always involve a long, drawn-out process.

In about 90 per cent of cases, she says, "there would be nothing further than a site assessment and some consultancy advice".

On a day-to-day level, archaeology doesn't match "the romantic illusion that people have. You do find wonderful things, but you wouldn't want to melt in the rain - you cannot be a little sugar cube."

Archaeologists work in "muddy sites that are frozen and wet. You have to be fairly fit if you are at the field end of the excavation. You empty wheelbarrows - you cannot afford to stand aside and wait for somebody else to do it.

"You do dig. There is a physical element as well as an academic side."