Big Pic: A Planet-Wide Map Of Martian Geology

From the equatorial highlands to the alluvial plains

The ground in Elysium is made of volcanic flows. That’s according to the newest geologic map of Mars, above, from the U.S. Geological Survey. Elysium Planitia is a named feature on Mars, but we’re guessing the area is rather drier than the mythical Elysium that Homer described as a meadowed paradise.

We’d love for you to go explore the map on your own here. Before you go, however, we’ll give you a guide on how to interpret it. All the different colored parts represent areas of crust that were formed at different times and from different processes. For example, the extensive green area near the north pole represents lowland plains formed during the Red Planet’s Hesperian Epoch, about 3.7 billion to 3 billion years ago. Scientists think those northern plains are covered in sediment from what were once Martian rivers and lakes. You can learn more about the green area, or any other colored area, in the extensive key on the right side of the map sheet.

One easy thing to spot are impact craters, which are roundish and marked on the map in bright yellow. Can you find Gale Crater, the site where NASA’s Curiosity rover landed? Gale Crater is just southwest of Elysium Planitia, which is the mostly pink area on the right side of the map.

NASA scientists made their first global map of Mars in 1978, using data from Mariner 9. Teams have made a few other maps since, as NASA sent more missions to the Red Planet. Compared to previous geologic maps, this new map finds a greater percentage of Mars’ crust originated from the first of its three epochs, the Noachian Epoch. The scientists who made this map also dated all the impact craters that are at least 150 kilometers (93 miles) in diameter. Mars’ biggest craters formed mostly early in the planet’s history—more than 80 of them formed in the Noachian Epoch, 4.5 billion to 3.7 billion years ago, but fewer than 10 formed after that.

The new map combines data and studies from the 1980s Viking missions onward. Among the data points the map uses are more than 600 million individual altitude measurements from the Mars Global Surveyor.