Sinuous Ridges in Argyre Basin
Sinuous Ridges in Argyre Basin
PSP_001508_1245  Science Theme: Landscape Evolution
This observation covers a portion of a sinuous ridge on the floor of Argyre Basin in the southern hemisphere of Mars.

The ridge is one of a number of similar ridges that split and rejoin as they wind across the floor of the basin and around hills and mountains. It is unclear what process is responsible for formation of the ridges, but glacial, coastal, and fluvial processes have all been suggested.

For example, they may represent ancient coastal shorelines, sediments deposited in a river flowing under glacial ice, or an ancient river bed that has been left standing in relief as surrounding, probably finer grained sediments were subsequently eroded away.

This image shows that the sediments forming the ridge include many large boulders that are often 1-2 meters or more in diameter. In addition, the sediments appear to occur in crude layers in a few locations. Such characteristics hold important clues to the process(es) responsible for formation of the ridge.

For example, if the ridge is the deposit formed by an ancient river then it may be difficult to account for the transport of so many large boulders.

Written by: John Grant  (24 January 2007)
Acquisition date
21 November 2006

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
251.0 km (156.0 miles)

Original image scale range
50.2 cm/pixel (with 2 x 2 binning) so objects ~151 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
86°, with the Sun about 4° above the horizon

Solar longitude
138.9°, Northern Summer

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  42.9°
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IRB color
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Merged IRB
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IRB color
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Black and white
map-projected  (53MB)
non-map           (103MB)

IRB color
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non-map           (88MB)

Merged IRB
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Merged RGB
map-projected  (150MB)

RGB color
non map           (81MB)
B&W label
Color label
Merged IRB label
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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/JPL/University of Arizona

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.