Figure 11-42: R I V U X G
Dry Streambed The rounding of the pebbles at this site indicate they were exposed to flowing water for a period lasting at least thousands of years. The pebbles, and certainly the largest rock (in the white circle), could not have been rounded or transported by winds in the thin Martian atmosphere. The jagged overhanging rock ledge (running down the middle of the image) appears to be the bank of the stream, undercut by erosion from the stream itself. Even the rocky ledge appears to be made of a sedimentary rock from prior exposure to water.
Dry Streambed The rounding of the pebbles at this site indicate they were exposed to flowing water for a period lasting at least thousands of years. The pebbles, and certainly the largest rock (in the white circle), could not have been rounded or transported by winds in the thin Martian atmosphere. The jagged overhanging rock ledge (running down the middle of the image) appears to be the bank of the stream, undercut by erosion from the stream itself. Even the rocky ledge appears to be made of a sedimentary rock from prior exposure to water.
(NASA)