The mystery of a strange Martian rock formation that has baffled scientists for decades has now been solved. Since its discovery in the 1960s, researchres have been trying to work out exactly what causes the undulating hills and sharp ridges of the Medusae Fossae formation. The formation covers an area of about 2 million sq km (770,000 sq miles) around the Martian equator and is described by Nasa as an'enigmatic pile of eroding sediments'. In the absence of any scientific explanation, conspiracy theorists have said that at least some of the exotic shapes found in the area belong to a'crashed UFO'. But a new study claims the rocks in this area of Mars are in fact the remains of volcanic eruptions that would have changed the climate of the red planet 3 billion years ago.