On the surface of Mars, meanders are found – dry river beds. How could they arise on a dry, cold planet with no open bodies of water?

There are two hypotheses for the origin of these landforms: a) once there was a warm climate on Mars and rivers flowed; now this planet is going through a period of great glaciation, and the ice is covered with sand; b) Mars experienced a brief temporary warming, presumably due to a collision with another cosmic body, during which violent streams of water formed valleys.