Young Fault Scarps on the Moon
Lunar features called lobate scarps were first seen on the highest resolution images from the Lunar Orbiter and Apollo missions of the 1960s and 70s. These scarps are the result of thrust faults which form when materials in the crust contract or are pushed together. New high resolution coverage from the Lunar Reconnaissance Orbiter, launched in 2009, has allowed the discovery and mapping of lobate scarps on a global scale, well beyond the limited Apollo zone. The distribution and character of these scarps indicates that the most likely reason for their formation is global contraction of the Moon caused by interior cooling. Their young age indicates that the Moon has contracted relatively recently in geologic time (1 billion years ago or sooner).