A Terraced Fan and Valley in a Crater
A Terraced Fan and Valley in a Crater
PSP_005583_1700  Science Theme: Mass Wasting Processes
This image shows a terraced fan (center left) located adjacent to a short valley. Terraced fans are rare deposits on Mars: they have only been seen in a few dozen locations.

On Earth, terraced fans are found in alluvial environments and in deltas. When water flowing down steep slopes, such as mountains or hills, encounters a flatter surface, the sediments carried by the water are deposited along the shallow slopes to form alluvial fans. Deltas can also produce terraced fans when water from rivers and streams meets oceans or lakes; a delta deposit results at the contact between the confined, fast-moving water (river/stream) and the open body of water (ocean/lake).

The fact that this Martian terraced fan is found adjacent to a valley supports the hypothesis that water was the mechanism that transported and deposited the material that now forms the fan. It is unclear, however, if this fan formed in an alluvial or deltaic environment, or by some other process.

Written by: Cathy Weitz  (31 October 2007)

This is a stereo pair with ESP_057801_1700.
Acquisition date
05 October 2007

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
259.1 km (161.0 miles)

Original image scale range
26.0 cm/pixel (with 1 x 1 binning) so objects ~78 cm across are resolved

Map projected scale
25 cm/pixel and North is up

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Emission angle

Phase angle

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

Solar longitude
325.6°, Northern Winter

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North azimuth:  97°
Sub-solar azimuth:  354.9°
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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.