MARSIS finds the Medusae Fossae Formation to be massive deposits more than 2.5 km thick in places.

Ash, dust, or ice deposits? Dielectric constant measurements hint at ice...

http://www.jpl.nasa.gov/news/news.cfm?release=2007-126

The preprint of the Science paper "Radar Sounding of the Medusae Fossae Formation Mars: Equatorial Ice or Dry, Low-Density Deposits?" is available http://www.sciencemag.org/cgi/content/abstract/1148112

Mars radar opens up a planet’s third dimension
http://www.esa.int/SPECIALS/Mars_Express/SEMIF74XQEF_0.html

Interesting animation in the latest press release.

Neat images, but a minor quibble. The image comparing the MARSIS and SHARAD images of the same region show only a single nadir track. It apparently is for the MarsExpress MARSIS image; the MRO SHARAD image gives a sufficiently different surface contour that it must have had a different nadir track.

Nonetheless, great insights into the planet's glacial geology.

Steve M

Edited to correct text and image