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National Scenic Riverways


cover of park brochure

park geology subheading
photo of river
Ozark National Scenic Riverway, Missouri

Ozark National Scenic Riverways (OZAR) is located on the Salem Plateau of the Ozark Plateau's physiographic province in southeastern Missouri. It covers the Current River from Montak State Park, near Salen, MO, on the northwest to the Ripley County line at the southeast end with a gap of about 4 miles around the town of Van Buren. The Jack Fork River portion extends from near the city of Mountain View northeast to the confluence with the Current River with another approximately 4 mile gap around the town of Eminence, MO.

The Ozark Plateaus is an upland region covering about 50,000 square miles mostly in southern Missouri and northern Arkansas, but extending into southeastern Kansas and northeastern Oklahoma. The boundary is generally defined by the Missouri River to the north, the Mississippi River on the east, the Arkansas River on the south and the Grand and Neosho rivers (Kansas and Oklahoma) on the west. The Ozark Plateaus are subdivided into three subprovinces: the Boston Mountains, the Springfield Plateau, and the Salem Plateau. The Boston Mountains, the southernmost extension of the Ozark Plateau, and located in northwest Arkansas and northeast Oklahoma, form the highest section with peaks greater than 2,000 feet. The Springfield Plateau, located in northwestern Arkansas, northeastern Oklahoma and southwestern Missouri is slightly higher than the Salem Plateau, and is mostly gently rolling plains and hills. Elevations range from about 1,700 feet at its easternmost point to about 1,000 feet at the Kansas border.

The Salem Plateau in south-central Missouri and northernmost Arkansas, is a dissected karst plain consisting of rolling uplands and rugged hills with deeply entrenched stream valleys ranges between about 1000 feet to 1,400 feet in elevation. Locally, elevations vary from about 510 feet on the Current River to 1,273 feet on Wildcat Mountain. There are abundant sinkholes, caves, springs, and losing streams.

Ozark National Scenic Riverways is covered by 16 topographic quadrangle maps. Of these, two geologic quadrangle maps have been completed: Eminence (Orndorff, et. al., 1999) and Powder Mill Ferry (McDowell and Harrison, 2000). Much of the following discussion is taken from the text accompanying these maps.

Geologic Setting

The Salem Plateau is underlain by flat-lying to gently dipping upper Cambrian to Lower Ordovician mostly dolomitic strata with scattered knobs of Middle Proterozoic volcanics. The Paleozoic strata are up to 1,800 feet thick and overlay an irregular buried basement surface of Middle Proterozoic rhyolite and granite. The Paleozoic rocks are overlain by unconsolidated surficial deposits of Tertiary to Quaternary age.


The basement rocks in the subject area are all granitic and rhyolitic rocks of Middle Proterozoic age and are the southwestern extension of the St. Francois Mountains to the northeast. Radiometric dating gives ages around 1,475 Ma to 1,500 Ma. From oldest to youngest, the Middle Proterozoic units are:

  • Shut-in Mountain: lava, rhyolite, densely welded (Ysi)
  • Sutton Creek Rhyolite: alkali rhyolite to rhyolite, massive (Ysc)
  • Coot Mountain - Lower Unit: interbedded ash-flow tuff, air-fall tuff and lava-alkali
    rhyolite, to alkali trachyte to trachyte to rhyolite, commonly massive and dense (Ycl)
  • Coot Mountain - Upper Unit: rhyolite to alkali rhyolite to alkali trachyte ash-flow tuff,
    densely welded, well-developed flow layering (Ycu)
  • Volcanoclastic conglomerate, breccia, and sandstone: interbedded; conglomerate of
    subrounded cobbles 3"-5" diameter; large pebbles of rhyolite (from Sutton Creek and Upper Coot Mountain) (Yvc)

The exposed Paleozoic strata are from oldest to youngest are:

  • Potosi Dolomite (Upper Cambrian)
  • Eminence Dolomite (Upper Cambrian-Ordovician)
  • Gasconade Dolomite (Ordovician)
  • Roubidoux Formation (Ordovician)

Generally, all the units below the Eminence are locally absent due to erosion or non-deposition over basement topographic highs. In the subsurface, the stratigraphy consists, from oldest to youngest, of the Lamotte Sandstone, Bonneterre Formation, Davis Formation, and Derby-Doerun Dolomite, all Upper Cambrian.

Tertiary and Quaternary deposits lie conformably over the Gasconade Dolomite. These include residuum derived from either the Gasconade or the Roubidoux Formation, terrace deposits, colluvium, and Holocene alluvium.

Structural Geology

Detailed geologic mapping shows that there are many faults in the and around the Ozark National Scenic Riverways. Most of the faults are vertical to steeply dipping, have strike-slip displacement, and trend northeasterly and northwesterly. Joints in the rocks generally are vertical and trend north-south and east-northeast.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A geology photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading


For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

selected links subheading

NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

General information about the park's education and intrepretive programs is available on the park's education webpage.

Also, see the online Teacher's Guide to Caves and Groundwater

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 12/07/2007  I   http://www.nature.nps.gov/geology/parks/ozar/index.cfm   I  Email: Webmaster
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