Today's Image of Mars shows Ceraunius Tholus (lower) and Uranius Tholus (upper), two Tharsis volcanoes on Mars. The fact that these volcanoes have craters on them tells us that the volcanoes are very old and inactive today. If they were active then lava flows would have covered any impact craters.
if you look at the bottom right of the larger Ceranius Tholus you will see that it is much lighter than the surrounding terrain. What you see are the deposits left from the global dust storm in 2001.
To give you some idea of scale, the large crater you see in the center of Ceraunius Tholus is approximately 25km in diameter. Ceraunius Tholus rises about as high above the Martian surface as Mt. Everest.
This image was taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in 2001. Clicking on it will take you to the original image fact page from NASA.