Harutaka Sakai, a geology professor at Kyushu University, western Japan, said the finding was based on his research of some 10 pieces of rock brought back by a Japan-China expedition team last year.

According to the research, the 8,848 m mountain used to comprise two giant fault plates, which had measured nearly 15,000 m in height.

But the upper sedimentary rock started sliding 20 million years ago, halving the mountain to its current level, the researcher said. It was later shaped into the current peak by glacial and natural weather erosion.

``The 10,000 m long fault was formed with accumulation of rock and soil for over 400 million years, and then slid at least 70 km toward the north,'' said Sakai.

The expedition team also found fossils, which support a theory that the present-day Everest peak used to lie underwater,he said.

``The present-day peak of the Everest was in fact filled with excrements of crabs and shrimps if you see it under a microscope,'' Sakai said.

``Today's Everest could have been something similar to a beach where micro-organisms had vigorously thrived,'' he said.