Rock and Ice in Deuteronilus Mensae

Individual mesas stand like islands in an ocean in this false-color THEMIS image that focuses on Deuteronilus Mensae. This region lies on the border between the rugged southern highlands and the flat northern lowlands and it shows features found in both.

Today, a dozen miles or more separate the mesas, but at one time they likely formed a continuous layer. Planetary scientists think that subsurface water escaped through cracks and faults, making the ground collapse. In this manner, the layer began to break apart into isolated pieces, and mesas developed as slopes retreated.
The neutron- and gamma-ray spectrometers on the Mars Odyssey spacecraft found strong evidence for water (as ice) in the ground, both here and elsewhere on Mars. When ice and lots of rocky debris mix, the result is a rock glacier. Like ordinary glaciers, which contain mostly just ice, a rock glacier can flow slowly, given the right temperatures and slopes.
As THEMIS flew over this scene before dawn, it captured heat radiation coming from the surface. The colors in the imdage (which was taken at infrared wavelengths) tell about the materials in the ground. Bluer colors show colder surface temperatures while yellows and reds indicate warmer ones.
During desert nights on Earth and Mars alike, rocks hold on to daytime heat better than fine-grain materials such as dust. Thus the yellow and red colors map where the surface has more rocks and boulders exposed, while blue colors show what are likely cold, dust-covered areas.
Icy Apron
Resembling a melting brick of ice cream, this mesa, like others, is wrapped by an apron of debris. Its blue color indicates the surface is cold and dusty. In addition, the mesa slopes that face the Sun also appear cold, instead of warm as might be expected.
This contrasts with other mesas in the image that show yellow and red edges, which point to exposures of rocky debris. Why is this feature so cold? One explanation, say scientists, is that this mesa, its slopes, and its encircling apron may all be saturated with water ice under a blanket of insulating dust.
Buckling Under Pressure
On Earth, glaciers typically develop creases and wrinkles as the ice flows. Where flows merge, they buckle and push up ridges, called moraines.
If conditions were right, several rock glaciers from nearby mesas might flow together and, where they meet, produce a feature looking like this.
Burial or Exhumation
The rim of an almost-buried crater, 16 kilometers (10 miles) across, barely pokes above the flat terrain. Reddish colors tell us the rim is rocky - as occurs with other craters nearby.
Are these craters being buried by icy flows from the mesas - or are they emerging from under an ice-rich, dusty layer that is vanishing? At this point, scientists can't say for sure.
Computer simulations suggest that Mars' climate is changing away from a global Ice Age in which a thick coating of dust-covered snow mantled much of the planet's middle latitudes. If this occurred, then the landscape here may be showing us relics of the last martian Ice Age.


Vital Statistics

47.5°N, 28.4°E
Image Size: 


100m (330 ft)