From 450-foot-high independence Monument, the largest free-standing rock formation in the park, to the smallest detail carved in stone, the grand sculptor in Colorado National Monument has been erosion. Time and lots of it -- has been a loyal ally, for it has taken millions of years to carve the many massive rock spires, huge domes, balanced rocks, arches, windows, stone pedestals, and sheer-walled canyons that make up the scenic splendor of the park. The erosive forces of water, wind, and frost work very slowly. Differences in the characteristics of the many layers of sandstone, shale, and other sedimentary rocks of the area help determine what form the rocks take. The harder rock layers are more resistant to erosion. One such layer -- the Kayenta Formation -- forms the protective caprock of Independence Monument and other bold, angular rock forms.