IF THE Glasgow School of Art's most famous building is to rise from the ashes of its devastating fire, right now the work required to revive the Mackintosh building and its library looks both possible and formidable.

The devastated library, one of the architectural gems of Scotland and the world, is now a charred box with its floor a chaotic, jagged, jumbled pile of ash, charcoal, burned wood, glass and metal.

Directly outside the library, in rooms and corridors, black walls show the effects of the fire, with bubbled varnish on surfaces exposing the original timber below, and blackened plaster friezes and statues - but remarkably much of the building looks relatively untouched by the blaze and is now watertight after the recent addition of a temporary roof.

This week the destroyed library has become the investigation site for a team of archaeologists from Edinburgh-based Kirkdale Archaeology.

They have begun the painstaking process of sifting through its remains to find artefacts that can be salvaged, and accurately map the damage to the room. It will take weeks.

Already several artefacts have been recovered or identified in the wreckage of the library and the west end of the building, including Mackintosh lamps, enamel broaches, and parts of tables and chairs. In the library itself, part of the mezzanine survives, as well as the wooden poles that supported the gallery.

When The Herald visited yesterday, the eight-person team were carefully sifting through the pile of debris nearest the library door: ash and charcoal was being removed and each artefact studied and saved.

We saw a pile of papers from burnt books being removed on a plastic tray.

The fire-blackened neoclassical sculptures outside the library will be cleaned and are expected to be returned to the building.

The archeologists are working through the library in one metre cubes, excavating the layers of ash in 25cm increments, with each new exposed surface photographed and recorded.

Each ash layer is then transferred to the Mackintosh Museum, where a team sifts through looking for salvageable items.

Several kinds of artefacts are to be kept, including all coloured glass, the best of exterior and interior window glass, library office glass and bookcase glass.

Only original metal fittings will be kept, with modern fittings disposed of,.

The work is being led by Gordon Ewart, director of Kirkdale Archaeology, who has previously worked on projects at Stirling Castle, Edinburgh Castle, Holyrood Palace and Linlithgow Palace.

He said: "Over the next few weeks we will work through the remains of the library excavating layer by later through the ash."