Is Tharsis a gaseous or lava-filled dome thus an indicator of an expansion of the crust?
A final observation of the red planet, its north polar terrain map displays few craters, while its south polar map shows many. A digital image map of Mars is available at: http://nssdc.gsfc.nasa.gov/image/planetary/mars/mars_dim.jpg . Could the north polar map be an area of new crust and therefore, younger than the south polar region? Mars strongly suits the expansion model by having many indicators of expansion and it raises many new questions for our own planet. Mars has two relatively small moons, Phobos and Deimos. Both moons display stretch markings and the apparent widening of older craters. It is surprising that these indicators of expansion are noticeable on such small bodies. New photos taken by Mars Global Surveyor show grooves and fractures possibly due to a large crater on Phobos. Phobos may be producing gas which is very likely water vapor. This is according to a Russian probe. A close up image of Phobos is available at: http://nssdc.gsfc.nasa.gov/image/planetary/mars/f854
