Intense squeezing, stretching, collapsing and bulging of Venus' landscape may explain why the planet is marked by an amazing network of faults and cracks, Magellan spacecraft geologists say.

Geological forces deformed the planet's Alpha highlands so extensively that the region looks like "it's been kneaded, like making bread dough," said Steve Saunders, Magellan's chief scientist at NASA's Jet Propulsion Laboratory.Elevated, extensively fractured regions - named tesserae after the Greek word for tile - cover 10 percent to 15 percent of the Venus surface, Saunders said Wednesday during a NASA briefing.

Magellan's highly detailed radar pictures of the cloud-covered planet are giving geologists clues to the formation of the cracked landscape. The tesserae contain many criss-crossing faults - which scientists believe can cause "Venusquakes" - long mountain ridges and broad deep troughs resembling Africa's Great Rift Valley.

The complex geology of tesserae indicates they were subjected to different forces at different times.