The planet Mars is home to thick layers of clay that can span hundreds of feet. Since they need water to form, these outcrops have long been of interest to scientists looking for signs of past life on the Red Planet.

In a new study in Nature Astronomy, scientists from The University of Texas at Austin and collaborators took a closer at these clay terrains and found that most formed near standing bodies of surface water, which were common on Mars billions of years ago. This environment would help foster the chemical weathering needed to create thick, mineral-rich layers of clay and could have provided the right mix of water, minerals and a calm environment for life to develop.