Knobby terrain in Northern Arabia Terra

Scaled Image

Image Credit: NASA/JPL/ASU

About this image

This THEMIS visible image shows a region in northern Arabia Terra. Knobby or 'scabby' plains units that mantle and modify a pre-existing cratered surface dominate the unusual landscape in this region. Several large (5-8 km diameter) impact craters seen in the upper left of the image have been extensively modified since their initial formation. The rims of these craters can still be seen, but the ejecta deposits and the surrounding plains have been buried by a layer of material.This mantling layer has itself been modified to produce a pitted, knobby surface. Circular depressions of all sizes, presumably the remnants of impact craters, are filled with smooth deposits. In some places large regions have been covered by this smooth material; an example can be seen in the lower right portion of this image. In many cases the impact craters have been extensively modified prior to their being filled. This modification indicates an erosion process that has removed material from the walls to produce shapes that vary from circular with crisp rims, to circular with no rims, to oblong and elliptical forms, and finally to irregular shapes whose initial circular outline can barely be detected. The slope of the channel at the top of the image has an unusual deposit of material that occurs preferentially on the cold, north-facing slope. Similar deposits are seen frequently at mid-northern and southern latitudes on Mars, and have a characteristic, rounded boundary that typically occurs at approximately the same distance below the ridge crest. It has been suggested that these deposits once draped the entire surface and have since been removed from all but the cold north-facing slopes. The presence and removal of ground ice may play an important role in the formation of this layer, as well as the knobby terrain and unusual features seen in this image. This image is the 22nd image in a series of daily images released by the THEMIS Team.

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


Image ID: 
V01272006 (View data in Mars Image Explorer)
2002-03-29 00:52
Thu, 2002-04-25
1024 pixels (19 km)
3648 pixels (69 km)
0.019066 km/pixel
0.019204 km/pixel


PNG | JPEG (high res) | JPEG (reduced res) | PDF | TIFF