<p>This image demonstrates the curious phenomenon called “topographic inversion.” The southern half of the picture is covered by a well-preserved lava flow. The flow stops just at the brink of descending a steep slope. Lava isn’t afraid of falling, so what happened here? 
</p><p>It is likely that the terrain to the north was once higher, and stopped the lava from flowing any further. Once the lava cooled, it protected the ground beneath it, while the softer rocks to the north continued to erode, “inverting” the topography so that what was once low-lying ground is now the top of a mesa.
</p><p>NASA/JPL/University of Arizona
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