Spirit Sol 105 Onion-layered structure

There is a great rock structure in Spirit Sol 105, at
http://www.lyle.org/mars/imagery/2P1...7L4M1.JPG.html

This can be compared to the following terrestrial image.
http://www.bangor.ac.uk/~azs80f/Phot...ges/image2.htm

See also the bottom of
http://atschool.eduweb.co.uk/radgeog...g/physical.PDF

If you look carefully there seems to be two more of these structures,
one on the left hand edge about a third of the way down, a second just
a little above and to the right of the second one.

The standard explanation for this type of weathering or erosion is
that it is a result of cyclical freezing and thawing -- with water of
course. That explanation seems a little weak and unsatisfactory to
explain what we are looking at. It looks more like something is
trying to push up from underneath something like an isolated instance
of a pillow lava. The Spirit rover is driving over basalt which is
consistent with onion-layered erosion in terrestrial igneous rocks. A
quick google search says that these onion layered are found in the
desert and also in cold wastes.

I suspect NASA is going to make a water connection and hold another
press conference saying yet again they have discovered water on Mars.

It would be nice if somebody would describe more carefully how these
structures are formed.

best
Michael
Mars Fossils, Pseudofossils and Problematica
http://aix1.uottawa.ca/~weinberg/mars
Come see our six new hallucinogenia!