Layers in Arabia Terra
Layers in Arabia Terra
PSP_004434_1885  Science Theme: Sedimentary/Layering Processes


This HiRISE image shows part of an extensive series of layered materials in a crater in Arabia Terra. The crater is about 60 kilometers (37 miles) in diameter and mostly filled with layered rocks, which are common throughout the area.

This image covers a swath of the crater from the center to the rim; the rim is at the northern edge (top). The northernmost layered materials are exposed as small buttes and stacks of layers, forming circular or elongated knobs. Further south, the appearance of the layers changes, forming more expansive outcrops with a few small knobs. This could be due to a change in the properties of the layers at given levels of the crater; materials of various strengths may erode at different rates. It might also reflect local slopes or erosional processes. This area looks darker-toned from a distance, but this appears to be due to partial covering of some of the layers by dark sand. A large sheet of sand is visible at the southern (bottom) edge of the image.

Many small faults are visible throughout the layers, expressed as small discontinuities and offsets; these indicate places where tectonic stresses have caused the layered deposits to break and shift.

The origin of such layers is not certain. Materials a few hundred kilometers away have been explored by NASA's Opportunity rover, and are sandstone formed by ancient dunes; the same could be true at this site, as sandstone on Earth often forms extensive layered deposits. Other possibilities include ancient lake or ocean sediments or volcanic airfall deposits. It is possible that multiple processes contributed to the rocks here, but the regularity of layering suggests a single repeated process.

Written by: Colin Dundas  (25 July 2007)
Acquisition date
07 July 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
275.3 km (171.1 miles)

Original image scale range
28.1 cm/pixel (with 1 x 1 binning) so objects ~84 cm across are resolved

Map projected scale
25 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
52°, with the Sun about 38° above the horizon

Solar longitude
272.2°, Northern Winter

For non-map projected images
North azimuth:  96°
Sub-solar azimuth:  323.4°
Black and white
map projected  non-map

Black and white
map-projected   (2555MB)

Black and white
map-projected  (1020MB)
non-map           (1254MB)

B&W label
EDR products

Black & white is 5 km across
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.