... relative smoothness and scarcity of impact craters. This Martian real estate is believed to be 2 billion years younger than the rest of the planet. Even so, it, too, is marked by "fluvial" features that resemble stream beds. Question #1 . How did Alba Patera get smoothed out or "reworked"? In other words, what happened to the ancient craters that must have pocked its surface, as they do everywhere else? Question #2 . Where did the water come from to cut Alba Patera's stream beds if all of the Martian water disappeared 2 billion years earlier? One line of thought maintains that "fluvial" does not mean "pluvial," and that Martian water has come from below rather than as rain from the atmosphere. Both fluvial episodes ... The present atmosphere of Mars, in consequence, contains little water vapor. But some of the Martian landscape, notably Alba Patera, raises questions about the above scenario. The anomalous characteristic of Alba Patera is its relative smoothness and scarcity of impact craters. This Martian real estate is believed to be 2 billion years younger than the rest of the planet. Even so, it, too, is marked by "fluvial" features that resemble stream beds. Question #1 . How did Alba Patera get smoothed out or "reworked"? In other words, what happened to the ancient craters that must have pocked its surface, as they do everywhere else? Question #2 . Where did the water come from to cut Alba Patera's stream beds if all of the Martian water disappeared ...