Well the difference between the Rockies and the Sierras -- Rockies are big, old, round mountains with long sloping grades and foothills. Sierras. Steep, sharp new mountains formed from extruded granite of plate tectonics.Instead of Julie Andrews dancing through a meadow, think hanging from a rope on El Capitan. Now that you've got the picture I wish I had one since I'll be called a liar! OK. So I'm finally going to breakdown and buy the digital camera for myself.
Check out Henness Pass Road, Rubicon Trail. That's the kind of terrain I'm talking about.
I forgot that Colorado builds actual roads through it's mountains.