Granite Dells, Ancient granite formation in Prescott, United States.

Granite Dells is a granite formation north of Prescott featuring exposed bedrock and large boulders shaped by erosion into rounded, rippled forms. Watson Lake and Willow Lake sit within these rocky landscapes and serve as central hubs for hiking, kayaking, rock climbing, and wildlife watching.

The Dells granite is Precambrian and has been radiometrically dated at 1.4 billion years old. Its pluton was intruded about one to two miles (1.6 to 3.2 km) below the surface, and the covering rocks have since eroded away. Weathering along joints, called spheroidal weathering, produced the rounded boulders and lumpy forms seen today.

The Peavine National Recreation Trail runs through these granite formations along the former Santa Fe, Prescott and Phoenix Railway route. Hikers can follow this path today and experience how the landscape once connected communities by rail.

The Peavine National Recreation Trail follows the old Santa Fe, Prescott and Phoenix Railway bed through the Dells and links up with the Iron King Trail, which runs along the former Prescott & Eastern Railroad through the eastern Dells. Both are rail-trail conversions, so walkers and cyclists share a graded route between the rock outcrops. Watson Lake and Willow Lake, the two man-made reservoirs, are the usual starting points.

The Dells granite has an unusually high uranium content, so homes built directly over it should be checked for radon seeping from the rock. The same rock was intruded as a pluton one to two miles (1.6 to 3.2 km) down and later exposed by erosion.