Eroded Scallops with Layers
Eroded Scallops with Layers
PSP_001938_2265  Science Theme: Sedimentary/Layering Processes
Western Utopia Planitia in the Northern mid-latitudes of Mars is marked by a peculiar type of depression with scalloped edges and by a network of polygonal fractures.

The scalloped depressions are typical features; a smooth layered terrain located between 40 and 60 degrees in both hemispheres. Scalloped depressions probably form by removal of ice-rich subsurface material by sublimation (ice transforming directly from a solid to a gaseous state), a process that may still be active today. Isolated scalloped depressions generally have a steep pole-facing scarp and a gentler equator-facing slope. This asymmetry is interpreted as being the result of difference in solar heating. Scalloped depressions may coalesce, leading to the formation of large areas of pitted terrain.

The polygonal pattern of fractures resembles permafrost polygons that form in terrestrial polar and high alpine regions by seasonal-to-annual contraction of the permafrost (permanently frozen ground). On Earth, such polygons indicate the presence of ground ice.

These landforms most likely show that sub-surface ice is present or has been present geologically recently at these latitudes, and they may slowly be continuing their development at the present time.

(NB: North is to the right.)

Written by: Alexandra Lefort  (9 January 2017)

This is a stereo pair with PSP_002439_2265.
Acquisition date
25 December 2006

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
301.0 km (187.1 miles)

Original image scale range
from 30.1 cm/pixel (with 1 x 1 binning) to 60.3 cm/pixel (with 2 x 2 binning)

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
57°, with the Sun about 33° above the horizon

Solar longitude
156.0°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  342.9°
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

Black and white
map-projected   (1169MB)

IRB color
map-projected   (741MB)

Black and white
map-projected  (617MB)
non-map           (433MB)

IRB color
map projected  (247MB)
non-map           (525MB)

Merged IRB
map projected  (374MB)

Merged RGB
map-projected  (359MB)

RGB color
non map           (514MB)
Map-projected, reduced-resolution
Full resolution JP2 download
Anaglyph details page

DTM details page

B&W label
Color label
Merged IRB label
Merged RGB label
EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

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NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.