The Granite Dells is a geological feature north of

Prescott, Arizona Prescott ( ) is a city in and the county seat of Yavapai County, Arizona, United States. As of 2020 United States census, 2020 Census, the city's population was 45,827. In 1864, Prescott was designated as the capital of the Arizona Territory, r ...

. The Dells consist of exposed bedrock and large boulders of granite that have eroded into an unusual lumpy, rippled appearance. Watson Lake and Willow Lake are small man-made reservoirs in this formation. The Peavine

National Recreation Trail The National Trails System is a series of trails in the United States designated "to promote the preservation of, public access to, travel within, and enjoyment and appreciation of the open-air, outdoor areas and historic resources of the Nati ...

follows the former railbed of the

Santa Fe, Prescott and Phoenix Railway The Santa Fe, Prescott and Phoenix Railway (SFP&P) was a common carrier railroad that later became an operating subsidiary of the Atchison, Topeka and Santa Fe Railway in Arizona. At Ash Fork, Arizona, the SFP&P connected with Santa Fe's opera ...

through the Granite Dells. This winding portion of the railroad was known as the "Peavine" because its twisting curves resembled that of a pea vine. It connects to the Iron King Trail, which follows the route of the old Prescott & Eastern Railroad through the eastern Granite Dells. Both are

rail trail A rail trail or railway walk is a shared-use path on a Right of way#Rail right of way, railway right of way. Rail trails are typically constructed after a railway has been abandoned and the track has been removed but may also share the rail corr ...

conversions.

Geology

The

Precambrian The Precambrian ( ; or pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

''Roadside Geology of Arizona,'' p. 168. Dells granite has been radiometrically dated at 1.4 billion years old. Its

pluton In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

was intruded at a depth of around one or two miles (1.6 to 3.2 km). These cover rocks have since been eroded away. Weathering along

joints A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

produced the rounded boulders and other unusual rock formations that characterize the Granite Dells. This process is called

spheroidal weathering Spheroidal weathering is a form of chemical weathering that affects jointed bedrock and results in the formation of concentric or spherical layers of highly decayed rock within weathered bedrock that is known as ''saprolite.'' When saprolite ...

, and is common in granitic terrains.Prescott Area Geological Field Guide, 1999, prepared for Earth Science Week. Copy available at

Yavapai College Yavapai College is a public community college in Yavapai County, Arizona. The main campus is in Prescott, with locations in Clarkdale, Prescott Valley, Chino Valley and Sedona. History Yavapai College was established in 1965 by means of a ...

library. The Dells granite has an unusually high

uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

content, and thus homes built over the granite should be checked for

radon Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to b ...

leaking from the granite.

References

* Chronic, Halka. ''Roadside Geology of Arizona,'' c. 1983, 23rd printing, Mountain Press Publishing Co. 322 pages. pp. 229–32 (''US 89A Sedona – Prescott''), pp. 165–68; Granite Dells, pp. 167–68.

External links

Prescott Trail System
*
Prescott Peavine National Recreation Trail
{{coord, 34, 36, 53, N, 112, 25, 06, W, display=title Geography of Yavapai County, Arizona Historic trails and roads in Arizona