|
Based on the available images of Mercury, this small planet's surface has been geologically inactive, other than occasional impacts, since soon after the large planetary impacts declined. Mercury continued to cool and shrink. This contraction caused the cold outer crust to break and slivers of crust to thrust over each other, forming rough-edged ridges. Mosaic of Mariner 10 images, courtesy of NASA and the Jet Propulsion Laboratory. Inset: Mariner 10 image of Discovery Scarp, courtesy of NASA, the Jet Propulsion Laboratory, and Northwestern University. Image originally from Davies M. E., Dwornik S. E., Gault D. E., and Strom R. G. (1978) Atlas of Mercury. NASA SP-423. |