Olympus Mons Martian surface atmospheric pressure is less than one percent of Earth's, the much lower gravity of Mars increases the atmosphere's scale height; in other words, Mars's atmosphere is expansive and does not drop off in density with height as sharply as Earth's. The composition of Olympus Mons is approximately 44% silicates, 17.5% iron oxides (which give the planet its red coloration) 7% aluminum, 6% magnesium, 6% calcium, and particularly high proportions of sulfur oxide with 7%. These results point to the surface being largely composed of basalts and other mafic rocks, which would have erupted as low viscosity lava flows
Olympus Mons This inhibition of southeasterly basal spreading in Olympus Mons could account for the structural and topographic asymmetry of the mountain. Numerical models of particle dynamics involving lateral differences in friction along the base of Olympus Mons have been shown to reproduce the volcano's present shape and asymmetry fairly well. It has been speculated that the detachment along the weak layers was aided by the presence of high-pressure water in the sediment pore spaces, which would have interesting astrobiological implications. If water-saturated zones still exist in sediments under the volcano, they would likely have been kept warm by a high geothermal