Earth's Grand Canyon is a wondrous spectacle of history and slow, steady power.  Mount Everest, the tallest of all Earth's mountains, reaches nearly thirty thousand feet above sea level.  As encompassing and overwhelming as these features are, geologic features on Mars far outmatch these tiny irregularities on Earth's crust.  Olympus Mons on Mars is the solar system's largest mountain (actually a shield volcano) towering twenty-five kilometers above the surrounding plain.  Valles Marineris is a huge gash cutting three quarters the distance around the planet, easily dwarfing the Grand Canyon on Earth.  Total relief on the Martian surface is thirty-two kilometers.  It would follow that adiabatic cooling is of major importance among Martian climatic controls.
     Below are links to images taken by the Mars Global Surveyor (Twicken and Hinson, 1996).  Like the normal lapse rate on Earth, the Martian lapse rate undergoes directional changes in its temperature curve as altitude increases.  Since these changes in Earth's normal lapse rate are attributed to different chemical and other characteristics in the stratification of the atmosphere, one can assume a similar explanation for the appearance of the Martian lapse rate.

       Late Fall Temperature versus Altitude
      Early Summer Temperature versus Altitude 

     The lack of definitive temperature inversions in the early summer chart suggest a fairly uniform atmosphere at that time.  Possibly, the warming and expanding atmosphere, with increasing summer winds provides the mechanism for a fairly homogenous atmosphere.
    Although Mars has very large relief, one must keep in mind that Mars has no oceans.  If the oceans were striped away on Earth, vast trenches would be revealed in subduction zones.  The relief on a waterless Earth would be much greater that what is now displayed on Mars.  This follows the fact that tectonic activity on Earth is still shaping and reshaping the crust while Mars is tectonically dead (or very nearly dead).