Tectonics of Mars southern highlands, and the Tharsis plateau. Much tectonic study of Mars seeks to explain the processes that led to the planet's division into these three provinces, and how their differing characteristics arose. Hypotheses proposed to explain how the two primary tectonic events may have occurred are usually divided into endogenic (arising from the planet itself) and exogenic (foreign to the planet, e.g., meteorite impact) processes. This distinction occurs throughout the study of tectonics on Mars. In general, Mars lacks unambiguous evidence that terrestrial-style plate tectonics has shaped its surface. However, in some places magnetic anomalies in the Martian crust that
The Angry Red Planet find a recording of an alien voice, which announces that the ship's crew were allowed to leave Mars so they could deliver a message to their home planet. The voice then states that "we of Mars" have been observing human development on Earth for many thousands of years and have determined that humanity's technology has far outpaced progress in cultural advancement. The alien then accuses humankind of invading Mars, warning that if future expeditions ever return to the Red Planet, the Earth would be destroyed in retaliation. "The Angry Red Planet" began as "The Planet Mars", a treatment written by