One of Earth’s distinctive features is it’s geologically dynamic nature. Heat is distributed through the molten core and mantle via vast slow convection currents, and these steady flows have fractured the crust into continent-sized plates. As these currents flow, they drag the plates around, in a process called Plate Tectonics. Where plates slide against each other, tension builds in the rock which jerks free as earthquakes, and where they collide directly, mountain ranges are thrust skywards. Without this process, the Earth would have been eroded into a perfectly smooth sphere covered by a shallow ocean billions of years ago.
But fresh observations of Vales Marineris by An Yin, a planetary geologist from UCLA, suggest that Mars may also have tectonic activity. Valles Marineris is one of the Solar System‘s great canyon systems: at 4000km long and reaching 200km wide at points, it’s twice the width of the Rift Valley in Africa and almost as long, and nine times longer than North America’s Grand Canyon. Yin studied detailed satellite imagery of Valles Marineris and noticed features similar to those he’d observed on fault structures which he’d studied in the Himalayas in Tibet, and also close to home in California. In a paper he submitted to the Geological Society of America late last year, he concluded that the two sides of the canyon have shifted relative to each other, suggesting that Mars posesses tectonic plates. However, unlike Earth with it’s fractured crust made of many plates of different sizes, he believes that Mars has just two plates. Mars is half the diameter of Earth, and so has retained a great deal less heat in its core, which means less energy for geological activity. This would have resulted in much less fracturing of the crust.
This news comes at an interesting time, as NASA announce their latest Discovery class mission, InSight. This lander is designed to drill beneath the Martian surface and monitor seismic activity and heat transfers, and now we know that it will have interesting data to return!