The Geology of Tuzigoot National Monument, Arizona

Tuzigoot National Monument sits on the Verde River in Yavapai County, Arizona, about 58 km (36 mi) southwest of Flagstaff. Proclaimed on July 25, 1939, it covers about 328 hectares (812 acres). It protects the archeological remains of the Sinagua culture, including a large hilltop pueblo and related historic and prehistoric sites and artifacts, as well as the ecologically sensitive Tavasci Marsh.

The name Tuzigoot is an Apache word meaning "crooked water." The pueblo, the remains of a large village several stories high, runs along the crest of a hill above the winding Verde River. Excavations there have produced some of the largest collections of Sinagua artifacts in the Verde Valley, dated between 1100 and 1450 CE. Tavasci Marsh, which the Park Service describes as the largest freshwater marsh in Arizona outside the Colorado River system, supports a varied community of plants and animals that people have used for food, medicine and tools since prehistoric times.

The pueblo's south rooms and the Verde River valley. Image from the National Park Service's page.

Where the park sits

Tuzigoot lies in the Verde Valley, in a zone of transition between two physiographic provinces, the Basin and Range and the Colorado Plateau; the Park Service places the monument in the Basin and Range. All of the bedrock inside the monument belongs to the Verde Formation, sediments laid down in the Miocene and Pliocene epochs. The pueblo is built on a ridge of the formation's lacustrine deposits, which stands above the surrounding valley floor.

The major geologic parts of the Verde Valley are:

• basin sediments;
• lacustrine, swamp and playa deposits of the Verde Formation;
• uplifted Paleozoic sedimentary rocks.

A river that moved

The Verde River has shaped the whole landscape around the monument. The ancestral and modern river built the floodplain and laid down the terraces on which the ruins stand, and Quaternary terrace deposits and river wash now drape the land around the park.

The park's geologic map shows that Tavasci Marsh and Peck's Lake occupy an old meander of the river, outlined by terrace deposits. As the river kept cutting down into its channel, it abandoned that loop. The marsh lies on the outside of the old bend, and Peck's Lake is a cutoff "oxbow" lake.

Part of the digital geologic map of Tuzigoot National Monument from the Geologic Resources Inventory. National Park Service.

Maps and inventories

Tuzigoot's page is part of the NPS Geodiversity Atlas, which gathers information on the rocks, minerals, sediments, fossils, landforms, soils and physical processes of each park to support education, geoconservation and management of both living and non-living parts of the ecosystem. The atlas draws on the Geologic Resources Inventory, which produces digital geologic maps and reports for more than 270 natural resource parks. Its products include scoping summaries from meetings where Park Service staff and local geologists planned the mapping, GIS map data, reports on each park's geologic features and management issues, and posters. A Soil Resources Inventory project had not been started for the monument when the page was written.

Sources

• National Park Service, "NPS Geodiversity Atlas—Tuzigoot National Monument, Arizona." https://www.nps.gov/articles/nps-geodiversity-atlas-tuzigoot-national-monument-arizona.htm
• The atlas page cites KellerLynn (2019) and National Park Service (2016).
• Geologic Resources Inventory products for the park: NPS DataStore, https://irma.nps.gov/DataStore/SavedSearch/Profile/3186
• The Park Service's page spells the lake both "Pecks Lake" and "Peck's Lake"; this page uses the second.