Nirgal Vallis

Scaled Image

Image Credit: NASA/JPL/ASU

About this image

This THEMIS image shows a sinuous valley network channel with sharp bends cutting across the cratered highlands of the southern hemisphere of Mars. The channel is named Nirgal Vallis, which is from the Babylonian word for Mars. Nirgal Vallis is a channel with a total length of approximately 500 km. It is approximately 6 km wide in this region. Gullies and alluvial deposits discovered by Mars Global Surveyor are clearly visible on the polar-facing (south) wall and floor of Nirgal Vallis. These gullies appear to emanate from a specific layer in the walls. There is a pronounced sparsity of gullies on the equator-ward facing slopes. The gullies have been proposed to have formed by the subsurface release of water. Patches of dunes are also seen on the channel floor, notably along the edges of the channel floor near the canyon walls. There is still debate within the scientific community as to how valley networks themselves form: surface runoff (rainfall/snowmelt) or headward erosion via groundwater sapping.

Please see the THEMIS Data Citation Note for details on crediting THEMIS images. 


Image ID: 
V01138003 (View data in Mars Image Explorer)
2002-03-17 22:33
Wed, 2002-03-27
1024 pixels (17 km)
3648 pixels (62 km)
0.017267 km/pixel
0.017392 km/pixel


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