NASA's Mars Global Surveyor shows an unconformity in a sequence of layered material in the martian north polar region created by erosion.

14 August 2006
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an unconformity in a sequence of layered material in the martian north polar region. MGS MOC has been examining many similar examples of unconformities created by erosion in the polar region this year. Long ago, the lower set of layers was deposited. Then, deposition ceased, and erosion occurred for some period. Then, the erosional period ended, and new layers were deposited. The older layers -- the ones deposited before the erosive event -- today appear truncated by the younger, more evenly-bedded layers. No one is certain what composes the north polar layers; they may be sequences of dust and ice.

Location near: 84.3°N, 235.6°W
Image width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Spring

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