Scientists are beginning to think perhaps Mars's volcanoes aren't extinct, but merely dormant. The evidence from new, more precise probes like the Mars Global Surveyor seem to indicate that a single "hot spot", moving underneath the Martian crust, may have powered all the volcanoes of the Tharsis Bulge. This is exactly opposite of what happens here on Earth, bringing yet more weirdness into one of the more peculiar places in the solar system.