What map are you looking at? Maybe if you post an image we can figure it out.
Look at either Steve's SPOT locator or the Spotwalla page (links above) in Terrain view. Shows clearly in the images Wagga posted above.
It looks to me that these shades of green are crude approximations of vegetation type. The color scheme changes as you zoom out but the general concept is similar - zig zaggy lines roughly delineating vegetation zones. If you zoom out to a different map scale (without contours) you'll see the Whitney area and other areas above treeline as white shaded regions. I'm guessing these vegetation layers just haven't been fully developed yet so they're somewhat off. If someone has a better explanation I'd like to read about it.
