Last updated: April 17, 2023
Inverted topography is a classic type of landform in the American southwest with its young monogenetic volcanic fields and rapid arid-land erosion. Many volcanic deposits, whether they are lava flows or ash-flow-tuffs, flow down river valleys and topographic lows and even fill them. Because they are resistant to erosion, the volcanic rocks may erode away more slowly than the rocks that had made the sides of the former valleys. With time and this process of differential erosion, lava flows that once travelled down valleys later stand as mesas. This process reverses the elevation of volcanic features relative to other features; e.g., lava-filled valleys become mesas, and, in turn, former topographic high points become valleys.
Inverted topography can sometimes help geologists determine the relative age of volcanic deposits. In areas with numerous lava flows of varying ages, the oldest will stand the highest above the current landscape with progressively younger flows becoming closer to the current land surface.
The most common type of inverted topography is formed by basaltic lava flows. But inverted topography can also form in locations of former valleys that were filled by ash-flow tuffs or lava domes as these rock types are also frequently harder than surrounding country rocks.
Figure (right): Schematic illustrations of the formation of inverted topography. Top graphic: Lava flows travel in topographic lows and valleys below surrounding topographic highs. Middle graphic: The hard volcanic rock protects the underlying country rock from erosion, eroding more slowly than the surrounding topography. Bottom graphic: stream valleys in which lava once flowed stand as high mesas above modern valleys.
NPS image by Trista Thornberry-Ehrlich after Muehlberger et al. (2005, p. 4).
National Parks and Inverted Topography
At least ten units of the National Park System are in or near volcanic fields with examples of inverted topography.
Capulin Volcano National Monument
Capulin Volcano NM sits within the Raton-Clayton Volcanic Field which experienced three phases of activity during the last 9 million years. The older lava flows stand at an elevation above the current ground surface level, whereas younger lava flows, like those erupted from Capulin Volcano, are the current ground surface level.
The Johnson Mesa lava flow was erupted approximately 8 million years ago and now holds up a low mesa west of Capulin Volcano NM. Jose Butte is a cinder cone that erupted about 2.5 million years ago.
Credit: Photo by Allyson Mathis.
Photo with feature labels added
Credit: Photo by Allyson Mathis.
Grand Canyon National Park
Examples of inverted topography are found near Grand Canyon. Some of the basaltic lava flows capping mesas and buttes in the region provide important age constraints for the age of the landscape as geologists can determine the age of the lava flows and calculate rates of erosion using the age information and how high the lava flow is above the regional ground level.
Petrified Forest National Park
The Hopi Buttes Volcanic Field, which is mostly north of Petrified Forest NP but extends into the park, consists mostly of maar and diatreme volcanoes along with associated basaltic lava flows.
Petroglyph National Monument
West Mesa in Petroglyph National Monument is held up by resistant lava flows that now stand above the general elevation of the land. These lava flows were erupted approximately 200,000 years ago.
Volcanic inverted topography is recognized for having geoheritage values since these landscapes can be easy to understand, can readily be observed, and result from the passage of geologic time and geologic change.
International Journal of Geoheritage and Parks—Inverted volcanic relief: Its importance in illustrating geological change and its geoheritage potential
National Park Sites in Areas with Inverted Topography
- capulin volcano national monument
- chiricahua national monument
- grand canyon national park
- grand canyon-parashant national monument
- lake mead national recreation area
- petrified forest national park
- petroglyph national monument
- sunset crater volcano national monument
- zion national park
- volcanic landscapes