The Positives and Negatives of Fissure Eruptions

Fissures on Mars are often distinguished as being linear (negative-relief) troughs or depressions such as this one (marked A in the cutout). Its edges appear raised, but that may be due to thick accumulations of wind-blown dust. Just to the south is a much narrower fissure (B) that is parallel to A but appears to be slightly raised (positive relief) with erupted material to either side.

More: https://uahirise.org/hipod/ESP_083598_1780
#Mars #science