[ETL]

Those features on Mars that you refer to may well have formed as a result of water flowing along the edges of regions of exposed square block and other jointing, like the type I provided examples of above. The water flow ultimately then carved the intersecting lines deeply such that the square forms are more pronounced.

"Erosional features in the outflow channels often form around obstacles such as craters..."

"Tiu Vallis appears to have started from an area of collapsed terrain (a region known as Hydaspis Chaos), moved northward through a fairly narrow channel, and then spread out and eroded a large area to the north and west. A more detailed view of the source shows the chaotic terrain, the initial channels, and various eroded features:

Erosional features in the outflow channels often form around obstacles such as craters..."

http://www.ig.utexas.edu/research/projects/mars/education/picture_pages/hydaspis_chaos.htm

[Jack Hydrazine]

What ever you do, don't mention the nature-made object on the right found on Mars.