AN archaeologist has discovered a giant carved rock face in the shape of a seal believed to be more than 8000 years old.

Edward Peterson, from Perthshire, who has studied rock art for 20 years, believes the 25ft sculpture proves Scotland's earliest inhabitants believed man descended from seals, and that the mammals were held sacred.

Mr Peterson said yesterday that his discovery at an isolated site between Killin and Lochearnhead, Perthshire, was ''the most significant proof that Stone Age man was religious''.

He said: ''There has never been anything like it discovered in Britain or Ireland. The sheer potential of this discovery is enormous.

''The sculpture is so well defined it proves that early Stone Age people, Scotland's indigenous people, were very religious and looked on the common seal as their ancestral spirit. These stone monuments were erected over the dead and paid homage to the whale and seal.

''There was a strong belief that people evolved from the seal. Seals acted like sentinels, watching and guarding the spirit of the dead as it rose with the rising of the sun.''

Mr Peterson, 73, who has carried out extensive studies of rock art in the UK and abroad, is convinced that his is the only discovery of its kind in Britain, although he said small sculpted seals were found at the top of some standing stones.

Mr Peterson said that the age of the site could be clearly determined by the depth of the peat surrounding the huge structure.

He said: ''I use a walking stick when I go to the area and it sticks in at least four feet in the ground, indicating a lot of water and an exceptionally old site.

''Peat indications and the way the rock is shaped show that the sculpture certainly dates from 6000BC and perhaps a little before.''

Mr Peterson said that man had already mastered the art of shaping stones to make tools long before the first appearance of the seal head on the rock face 8000 years ago.

He said: ''Neanderthal man was already working, chipping and cutting holes in stones, so there was no problem in the megalithic age.

''To sculpt something like this in a rock face, they simply used harder rocks to roughly cut, chip away and shape the stone.

''They were even able to polish the stone to quite a high standard, although much of the evidence for this is diminished through time and erosion.''

Mr Peterson will present his findings on the carved rock face today at a seminar in the Smith Museum in Stirling.