Formation of Clays

At https://phys.org/print437125828.html … in this instance, clay formation on the planet Mars. Temperature on Mars is well below freezing but it must once have been warmer if liquid water carved out features on the surface. Not only that but the water had to be warm enough for surface clays to form. The researchers opt for a series of short term warming episodes leading to temporary wet climates. All speculation of course.