Researchers at the University of Portsmouth believe they have solved an ancient Mediterranean mystery.
The mystery of how 2ft deep tracks were cut into the rock of Malta has been a puzzle for years.
Now Professor Derek Mottershead, of the university's geography department, has followed generations of scholars to unravel the mysteries of the Maltese landscape.
The tracks, or ruts, were almost certainly caused by carts because the rock was not strong enough to support the wooden wheels of loaded carts.
They are up to 2ft deep and more than 30km of them run in pairs criss-crossing the island.
Professor Mottershead's team came up with a design of a cart to fit the field evidence, estimated its weight and calculated the stresses involved.
They discovered that in some places the rock was so soft that after heavy rain a single passage of a cart could cause the rock to fail.
Professor Mottershead said: 'The ruts have been studied and talked about for centuries and though it is obvious they are related to vehicles nobody understood how they were made or even when.
'The underlying rock in Malta is weak and when it's wet it loses about 80 per cent of its strength.
'What is unique to Malta is the sheer number of ruts. For years they have attracted the attention of archaeologists but until now we didn't have a convincing explanation of the mechanics of how they could have been formed.'
The team included Dr Alastair Pearson and Martin Schaefer, also of the University of Portsmouth. Their research was published in the journal Antiquity.
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