The western portion of the mountain range has pale green formations, differing from the eastern, steeply carved and striking brick-red volcanics.

[5] The range stretches approximately 25 miles (40 km) in an east-west direction, and reaches an elevation of 2,695 feet (821 m) at Savahia Peak at the western end.

These linear ridges mark the tops of tilted crustal blocks lying in the hanging wall of an extensive detachment fault, and the range as a whole comprises one of the best exposed and most studied metamorphic core complexes in the world.

The entire region accommodated major crustal extension between the Sierra Nevada block and the Colorado Plateau during the early and middle Miocene.

Francisco Garcés, the explorer, missionary, and regional "peacemaker" based at Mission San Xavier del Bac had initiated expeditions along the river and surrounding terrain through and past the Whipples in the early 1770s.

They passed through the range en route to the Needles area and onwards inland, traveling in peace with the local indigenous people west of the river.