If Lava Mingled with Ground Ice on Mars
Written by Linda M.V. Martel
posted June 26, 2001
Hawai'i Institute of Geophysics and Planetology

Clusters of small cones on the lava plains of Mars have caught the attention of planetary geologists for years for a simple and compelling reason: ground ice. These cones look like volcanic rootless cones found on Earth where hot lava flows over wet surfaces such as marshes, shallow lakes or shallow aquifers. Steam explosions fragment the lava into small pieces that fall into cone-shaped debris piles. Peter Lanagan, Alfred McEwen, Laszlo Keszthelyi (University of
Arizona), and Thorvaldur Thordarson (University of Hawai`i) recently identified groups of cones in the equatorial region of Mars using new high-resolution Mars Orbiter Camera (MOC) images. They report that the Martian cones have the same appearance, size, and geologic setting as rootless cones found in Iceland. If the Martian and terrestrial cones formed in the same way, then the Martian cones mark
places where ground ice or groundwater existed at the time the lavas surged across the surface, estimated to be less than 10 million years ago, and where ground ice may still be today.

Reference:

Lanagan, P.D., A. S. McEwen, L. P. Keszthelyi, and T. Thordarson (2001) Rootless cones on Mars indicating the presence of shallow equatorial ground ice in recent times, Geophysical Research Letters, vol. 28, p. 2365-2368.

For full story, see http://www.psrd.hawaii.edu/June01/lavaIceMars.html