The image shows the effect of gas jets behaving almost like geysers. Translucent slabs of carbon-dioxide ice near Mars's south pole allow light from the springtime Sun (here just 8° above the horizon) to penetrate the slab and heat the surface below. The heat gets trapped (frozen CO2
is opaque at infrared wavelengths) and causes ice to sublimate into gas until sufficient pressure builds up to crack the ice. Escaping gas carries dust with it, which creates the fan-shaped deposits seen here. Click here
for more information and to see a larger view.
NASA / JPL / Univ. of Arizona