KARST – kärst. An irregular limestone region with sinkholes, underground streams, and caverns; Noun, earliest use 1902 German, from Slovene dialect or Croatian dialect kras, kars, type of rock, region composed of such rock (Source: Merriam-Webster)
CaCO3 + H+ + HCO3– —–> Ca2+ + 2HCO3–
calcite + hydrogen ions + bicarbonate —–> calcium ions + bicarbonateKarst in the United States.
Karst features and landscapes occur where rocks prone to dissolution by weakly acidic natural waters occur at Earth’s surface or in the shallow subsurface. This includes limestones, marbles, dolostones, gypsum and rock salt. In the U.S., fully 1/5th of the surface area includes karst features. Twenty states, including Florida, Missouri, and Kentucky, are dominated by karst landscapes. Missouri alone has more than 6,000 recognized karst caverns and caves. Common karst features include sinkholes, collapse pits, disappearing streams, swallets, and caves. Using geologic maps produced by State Geological Surveys, including AZGS, the US Geological Survey built a national map showing areas of karst or potential karst or pseudokarst development (Weary and Doctor, 2014). The Karst in Arizona image below stems from that map product. Areas mantled in dark blue represent dryer, less humid, lower elevation environments; turquoise mantling reflects wetter, more humid, higher elevation environments.
Karst landscapes & features
Karst in Arizona. In Arizona karst landscapes and features are common and occur in the state’s three physiographic regions: Colorado Plateau, Transition Zone, and the Basin and Range Province. On northern Arizona’s Colorado Plateau the Permian Kaibab Formation, a karstic limestone, is prevalent at the surface and in the shallow subsurface.
This graphic above shows karst areas identified in Arizona – most occur in Pennsylvanian and Permian-age carbonates. For the complete document - KML file, GIS data and report of "Karst in the United States: A Digital Map Compilation and Database".
Paleokarst features are abundant in the buried Mississippian Redwall limestone. Collapse of overlying strata (i.e., overburden) into paleokarst caverns of the Redwall limestone drives the formation of fresh karstic features, e.g., Devil’s Kitchen sinkhole near Sedona (Lindberg, 2010). The breccia pipes of northern Arizona formed when overburden comprising Mesozoic- and Paleozoic-age rock (Permian and Pennsylvanian)- collapsed into the Redwall Limestone roughly between 200 my and 260 my ago.
A good source of karst literature in Arizona is the Bibliography of Arizona Geology -AZGeoBib. AZGeoBib comprises more than 13,000 citations of geologic and geohydrology research. A search of the database for ‘karst’ identifies 70 citations of research papers published between 1902 and 2002. (Note: the bibliography of Arizona Geology has not been updated since the early 2000s, so more recent papers are not included.)
Karst Aquifers and Breccia Pipes.
Karst Caves for Tourists and Spelunkers. Caves are among the most common of karst features and people flock to them for an otherworldly experience. Dissolution of soluble rocks (limestones, dolostones, and marble) can produce open caverns that abound in stunning products of stalactites, stalagmites, drapery formations (curtains), capillary tubes (hollow stalactites), columns, flowstone, and less commonly, helectites.
Caves of note in Arizona, in part because of their accessibility, include: Kartchner Caverns in Kartchner Cavern State Park, south of Benson, Arizona; Colossal Cave in Colossal Cave Mountain Park, Pima County; Cave of the Bells in the Coronado National Forest, Santa Rita Mountains; Grand Canyon Caverns east of Peach Springs, Arizona; Peppersauce Cave in the Santa Catalina Mountains, near Oracle, Arizona.
The Bibliography of Arizona Geology includes 108 citations related to cave geology, ecology or environment. You can review those citations here.
CAVEAT. Caves are surprisingly fragile environments. And they are dangerous. Please take great care in entering and exploring natural caverns. There are thousands of caves in Arizona, only a few are well-explored, well-known, and monitored regularly. Please enter unsupervised caverns with great care and with experienced cavers carrying multiple light sources. Caves are inherently dangerous, take all due precautions for the safety of you and your team. The National Speleological Society provides “A Guide to Responsible Caving” to assist cavers – new and experienced – in appropriate caving safety and etiquette.
Geologic Hazards of Karst Areas
From A Home Buyer's Guide to Geologic Hazards in Arizona. “Hazards from karst include the formation of sinkholes or collapse pits, as well as cracking of walls, foundations, roads, and other structures. Less obvious but equally important are the impacts karst can have on water quality. Networks of interconnected caverns and voids allow contaminants such as sewage, landfill leachate, or hazardous chemicals to travel unimpeded into shallow aquifers that may supply drinking water. The possible presence of solution features must be carefully considered when making land-management decisions, including protecting water supply, locating septic systems, and siting of waste disposal facilities."
For a fuller treatment of karst hazards see the Karst Hazards section of Ray Harris’ (2002) “A review and bibliography of Karst Features of the Colorado Plateau, Arizona”. This report includes a map of the principal karst area of Arizona's Colorado Plateau, as well as numerous black & white photos of karst features, including open fractures and sinkholes.
Select Karst Features in Central and Northern Arizona
McCauley Sinks. The McCauley Sinks comprises several dozen small sinkholes restricted to a 3-km-wide depression. The sinks are arranged in a series of gentle arcs or rings. The size of individual sinks varies, but the largest are ~ 100 m in diameter and 50 m deep. The sinks crop out in Permian Kaibab Formation limestones. Collapse here may be the result of Karst formations in the older Permian Schnebly Hill Formation, which contains evaporites, principally halite (rock salt). From Neal and Johnson, 2002. Slow subsidence at some sinkholes is an ongoing process (Brian Conway, pers. comm, ca. 2015).
Sedona Devils Kitchen Sinkhole. One of the earliest descriptions of Devils Kitchen, which involved a collapse event there, was retold by long-term resident Albert E. Thompson (1968), "My parents were living in Sedona in the early1880s and heard the crash when the spot caved in. Mother said the dust from the cave-in filled the air all day and the sun looked like it was shining through heavy smoke. Her brother, Jim James, was the first one to see the new hole in the ground".
In late 1989, a second historic collapse event occurred at Devils Kitchen, enlarging the opening by as much as 1/3rd. The 1989 event was largely limited to the north wall, where a gigantic block, detached along three bounding walls from its caprock, rotated outward into the opening without dropping to a lower elevation. Edges of the newly broken rocks are highly angular and the surface soil has not yet begun to slough off.
Collapse of the southernmost wall of the sinkhole predated historic collapse events and probably represents an early, formative event in the history of Devils Kitchen. In contrast to the fresh, angular appearance of historically broken blocks, blocks of the south wall display rounded edges and the surfaces carry a patina of manganese oxide that suggests open exposure over several hundred years.
• Conway, B.D. and Cook, J.P., Monitoring Evaporite Karst Activity and Land Subsidence In The Holbrook Basin, Arizona Using Interferometric Synthetic Aperture Radar (Insar), 8 p.
• Cook, J.P., 2018, Investigations of the Possible Underground Extent of La Posta Quemada Sinkhole, Colossal Cave Mountain Park, Pima County, Arizona. Arizona Geological Survey Open-File Report OFR-18-01, 19 p
• Galloway, D.L., Jones, D.R. and Ingebritsen, S.E., 2000, Land Subsidence in the United States. US Geological Survey Fact Sheet-165-00.
• Gootee, B.F., 2014, The Redwall Limestone - The fascinating history and character of Grand Canyon's thickest limestone. Arizona Geological Survey Powerpoint Presentation http://repository.azgs.az.gov/uri_gin/azgs/dlio/1572
• Harris, R.C., 2002, A review and bibliography of Karst Features of the Colorado Plateau, Arizona.
• Harris, R.C. and Pearthree, P.A., 2002, A Home Buyer's Guide to Geologic Hazards in Arizona. Arizona Geological Survey Down-to-Earth #13, 48 p.
• Lindberg, P.A., 2009, Devil’s Kitchen Sinkhole: A potential geohazard. Arizona Geology, Winter 2009, v. 39, #3,
• Lindberg, P.A., 2010, Sedona Sinkholes and Groundwater Flow: The Geologic History of Their Evolution, Coconino and Yavapai Counties, Arizona:
• Lindberg, P.A., 2010, Geologic Report of the Devils Kitchen sinkhole, Sedona, Arizona: Arizona Geological Survey Contributed Report CR-10-B, 19 p.
• Neal, J.T. and Johnson, K.S., 2002, McCauley Sinks: A compound breccia pipe in evaporite karst, Holbrook Basin, Arizona, U.S.A. Carbonates and Evaporates v. 17, p. 98-106.
• Rauzi, S.L., 2002, Arizona has Salt!. Arizona Geological Survey, Circulars (C)-30, 42 p.
• Rauzi, S.L., 2000, Permian Salt in the Holbrook Basin, Arizona. Arizona Geological Survey Open File Report, OFR-00-03, 6 map plates, 20 p.
• Rauzi, S.L. and Neal, T.J., 1996, Storage Opportunities in Arizona Bedded Evaporites. Arizona Geological Survey Open File Report, OFR-96-27, 16 p.
• Veni, G. and 7 others, Living with Karst: A Fragile Foundation. AGI Environmental Awareness Series #4, 69 p.
• Weary, D.J., and Doctor, D.H., 2014, Karst in the United States: A digital map compilation and database: U.S. Geological Survey Open-File Report 2014–1156, 23 p.
• Wenrich K.J., Sutphin, H.B., 1988, Recognition of Breccia Pipes in northern Arizona. Arizona Bureau of Geology and Mineral Technology, Fieldnotes, V. 18, #1, Spring 1988, 5p.