Many are impressed that Denver is one mile above sea level, yet the Mile High City is less than the average elevation of Colorado. At 6,800 feet above sea level, Colorado has the highest average elevation in the nation. Thirty one percent (32,649 square miles) of the state is  "mountainous", or greater than 8000 feet above mean sea level. The vertical range in elevation is more than two miles, ranging from a low of 3,313 feet above sea level where the Arikaree River enters Kansas, to 14,440' at the crest of Mount Elbert near the center of the state. We have 58 named peaks that are greater than 14,000 feet in elevation (the fourteeners). And, there are well over 700 peaks higher than 13,000 feet above sea level.  Why?

Two phenomena cause the higher elevation: 1. a thicker crust and 2. a thinner lithospheric mantle. And why is that?  Well, the crust is apparently thicker because it is old and cold. And, the lithosperic mantle is currently being thinned by heat coming from deeper in the mantle.