Scientists theorise that the thickness and the composition of these layers in the south polar region could hold a record of climate change just as years of drought and years of plentiful rain change the width of rings in an Earth tree trunk. This mosaic shows complex erosional patterns that have developed on the south polar cap, perhaps by a combination of sublimation, wind erosion, and ground-collapse. These images were acquired by the Mars Orbiter Camera aboard the Mars Global Surveyor spacecraft during the southern spring season in October 1999. Each of these two pictures is a mosaic of many individual MOC images. They show features at the scale of a small house.
Sunlight illuminates each scene from the left.
The grey gaps in the the second mosaic, above, are areas that were not covered by MOC in October 1999. All rights reserved.