Volcanology of Mars through the crust to produce volcanic mountains. However, the largest volcano on the planet, Olympus Mons, is thought to have formed when the plates were not moving. Olympus Mons may have formed just after the plate motion stopped. The mare-like plains on Mars are roughly 3 to 3.5 billion years old. The giant shield volcanoes are younger, formed between 1 and 2 billion years ago. Olympus Mons may be "as young as 200 million years." Norman H. Sleep, professor of geophysics at Stanford University, described how the three volcanoes that form a line along the Tharsis Ridge may be extinct
Climate of Mars have once had a much thicker and warmer atmosphere, and oceans and/or lakes may have been present. It has, however, proven extremely difficult to construct convincing global climate models for Mars which produce temperatures above 0 °C at any point in its history, although this may simply reflect problems in accurately calibrating such models. Evidence of a geologically recent, extreme ice age on Mars was published in 2016. Just 370,000 years ago, the planet would have appeared more white than red. Mars' temperature and circulation vary every Martian year (as expected for any planet with an atmosphere). Mars lacks oceans,