There were some patches of snow a few inches deep and some sections of pure ice. (automobilemag.com)
A meteorite impact has revealed nearly pure ice (white dot in yellow - brown smudge)-- possibly left from an earlier ice age — beneath a thin layer of martian soil. (sciencemag.org)
By measuring the remaining difference — the 20,000 - year old ice deep in the West Antarctic ice sheet is about 1 degree Celsius cooler than the surface — the scientists were able to estimate the original temperature based on how fast pure ice warms up. (sciencedaily.com)