It is just as well that the birds in London's Natural History Museum are dead and stuffed. They lie in rows inside mahogany cases, sharing a conventional museum existence with miscellaneous fossils, ossified tree stumps and skeletons.

Dead, they are unaware that tomorrow the doors to the adjacent geological galleries will be thrown open to allow a blast of the latest in high-technology exhibitry to rush into their more sober halls.

On Saturday the public will see the first fruits of a Pounds 12 million project to turn the geological museum into what can only be called an "earth science experience".

Serried cases of minerals and metals, the geological counterparts of stuffed birds, have been banished to temporary exhibition space. In their place will be a cascading journey through volcanoes; earthquakes as realistic as the Health and Safety Executive would allow; drifting continents; and swirling waters reproducing the erosion of the mountainous products of plate tectonics.

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The project is the most ambitious the museum has ever undertaken. It has built some pioneering exhibitions in the life sciences over the past 20 years. More recently it decided that geology's image needed modernising. Surveys showed the public thought it boring and irrelevant.

Giles Clarke, head of exhibitions and education at the museum, says that today such galleries must be "competing for the public's leisure time - with shopping, sitting in front of the television and football".

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So from tomorrow the earth galleries will exude the excitement of earthly forces. The visitor enters through a hall of cathedral dimensions and almost religious atmosphere, its walls lined in grey slate etched with images of the solar system.

In place of an altar, however, there is a massive globe to worship, suspended in the air. It gazes down the hall like a disembodied eyeball. An escalator pulls the visitor up from the ground, through the rotating earth and on to the beginning of the exhibition.

Last week the galleries were still a building site. Through the scaffolding protruded the wreck of a car covered in volcanic ash and the corner of a Kobe supermarket that will shake just as supermarkets did during last year's earthquake, as revealed by supermarket security films. Further on a woman was pasting gold paint on to a model of the world's mountains.

The designers ranged from sculptors to academics to the design company responsible for the spectacular Museum of the Moving Image, Neal Potter.

"We tended not to put them all in the same room together," says Dr Clarke. But the result is not a theme park, he says.

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"It is a very specialist business communicating scientific information to the public. Interpretation is really the critical thing. Rocks do not speak for themselves. We're very keen to make people realise that science is a happening activity, to take people along in the process."

Visitors will be encouraged to think about how to study what they see. They will be shown, for example, the tools of the geologists' trade: monitors at the top of the escalator flash the details of recent earthquakes.

Nevertheless, some may cringe to see supermarkets and collapsing walls judged a better use of space than precious specimens, although there will be many of these scattered through the galleries.

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The old galleries were filled with specimens. But they were built as a working geologists' museum and have gradually lost that role, more so since the British Geological Survey parted company from the geological museum, left the site and handed the galleries to the Natural History Museum in 1985.

Academic geologists are delighted with the potential of the galleries to improve the image of geology, claims Dr Clarke. So those who suffer most from the renovation will probably be amateur geologists who do not need things explained from scratch.

"They were very concerned that we shouldn't clear away all the specimens," says Dr Clarke. He hopes such people will find valuable a soon-to-be-built resources centre. This and three other galleries will be added over the next two years.

When those galleries are ready, the cultural change from geological museum to "mind-blowing journey through the centre of the earth", as the museum's publicity material terms it, will be complete.

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