From The Archives: Martian Plateau And Plain Terrain

The photo gracing the cover of the January 31, 1972, issue shows a Martian equatorial depression, possibly caused by the collapse from volcanic activity or subsurface ice melting.

The depression was measured around 8,000 to 10,000 ft. deep, along scarps seen at the right of the image. These are marked by parallel grooves resembling those left by terrestrial avalanches on steep grades.

Irregular terrain on the left side of the depression is younger than the surrounding plateau, and we reported that it was formed through the cutting back of the higher surface. North is to the left, and the sun is shining from the west, or bottom. 

The cover was taken by Jet Propulsion Laboratory's Mariner 9, from an altitude of 1,130 mi.

Read more about Martian features on page 44. 

See the cover and read the full issue dated January 31, 1972. 

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