The Hoodoos of Mars

On Mars, NASA's Mars Reconnaissance Orbiter often sees inverted river channels preserved perched above the surrounding terrain because the sediment inside the river channel was stronger than its surroundings. This is common in the American Southwest in places where lava flowed down river channels and the surrounding sandstone subsequently eroded away leaving ridges in places that started as valleys. There's another example of high-standing columns protected by a strong cap rock, called "hoodoos." Looking more closely at our image, we see what looks like a crater and its rays of ejecta, preserved and slightly higher than the surrounding terrain, possibly due to a similar process. https://photojournal.jpl.nasa.gov/catalog/PIA21883