Geodiversity refers to the full variety of natural geologic (rocks, minerals, sediments, fossils, landforms, and physical processes) and soil resources and processes that occur in the park. A product of the Geologic Resources Inventory, the NPS Geodiversity Atlas delivers information in support of education, Geoconservation, and integrated management of living (biotic) and non-living (abiotic) components of the ecosystem.
Geologic Features and Processes
Capulin Volcano is one of the tallest and most perfectly formed cinder cones in North America. The volcano stands 2,494 m (8,182 ft) above sea level and nearly 400 m (1,300 ft) above the surrounding plain. It is the primary geologic feature at Capulin Volcano National Monument and a fundamental resource and value of the monument (National Park Service 2014c).
Capulin Volcano lies near the center of the 20,000 km2 (8,000 mi2 ) Raton-Clayton volcanic field, which extends for more than 130 km (80 mi) between the cities of Raton and Clayton from which the field received its name.
The eruption of Capulin Volcano occurred about 55,000 years ago (Pleistocene Epoch) toward the end of the most recent phase of volcanism in the RatonClayton volcanic field. Hills, peaks, and other features both younger and older than Capulin Volcano formed as a result of regional volcanic activity. These features can be seen from the Crater Rim Trail. The largest of these features is Sierra Grande, an extinct volcano rising 670 m (2,200 ft) above the surrounding plain to the southeast of Capulin Volcano. To the northwest, mesas such as Johnson Mesa are capped with some of the oldest lava in the field.
Geologic features and processes at Capulin Volcano National Monument include the following:
- Capulin Basalt. Capulin Volcano National Monument and the surrounding area are composed entirely of a single, formally named map unit— Capulin Basalt. Analysis of rock samples from Capulin Volcano and nearby Baby Capulin, a cinder cone outside the monument, found that the rock is technically a “trachybasalt,” having more abundant alkali elements, such as sodium and potassium, than true basalt. The presence of Dakota Sandstone xenoliths (foreign rock fragments) and xenocrysts (foreign crystals) is a characteristic feature of Capulin Basalt. Silica from Dakota Sandstone quartz grains is a factor in the relatively high amount of silica (50%–55%) in Capulin Basalt.
- Raton-Clayton Volcanic Field. Capulin Volcano National Monument is part of the 20,000-km2 (8,000-mi2 ) Raton-Clayton volcanic field, which has been active episodically for the past 9 million years in three phases: (1) Raton phase, which had two distinct episodes (9.0 million–7.3 million years ago and 5.6–3.5 million years ago); (2) Clayton phase (3.0 million–2.2 million years ago); and (3) Capulin phase (1.69 million–32,000 years ago). Capulin Volcano erupted during the Capulin phase. The volcanic field consists of an estimated 125 vents and is characterized by a low volumetric eruption rate and inverted topography
- Capulin Volcano. Not only is Capulin Volcano a type example of a cinder cone, it is archetypal— bigger and more perfectly formed than most cinder cones. The beauty of this volcano is the reason for its inclusion in the National Park System.
- Volcanic Features. Richman (2010)—the source for the GRI GIS data set—mapped Capulin Volcano and the complex boca, delineating two boca ramparts, 16 lava cascades, 19 lava lakes, 15 lava levees, 18 lava ridges, one pooled lava flow, one push-up, two rafted cinder cones, 24 spatter deposits, one spatter flow, 23 squeeze-ups, 18 tumuli, and seven vents.
- Age of Capulin Volcano. Once considered less than 10,000 years old, Capulin Volcano is now known to have formed 55,000 ± 2,000 years ago.
- View from Capulin Volcano. The view from the crater rim is probably what led Homer Farr, the custodian of Capulin Mountain National Monument (former name of the monument) from 1923 to 1955, to build a road to the summit. The “dramatic view” is one of four statements of significance identified in the monument’s general management plan; the other three are the classic cinder cone, occurrence in the geologically diverse Raton-Clayton volcanic field, and the cinder cone’s accessibility.
- Playa Lakes. Playa lakes—ephemeral lakes in arid or semiarid regions that appear in the wet season and subsequently dry up—are one of the only nonvolcanic features in the viewshed of Capulin Volcano National Monument. Playa lakes are visible to the south and east of Capulin Volcano.
- Aeolian Features. A notable aeolian (windblown) feature at Capulin Volcano National Monument is the asymmetrical crater rim, which is higher on the northeastern side. At the time of cone building, prevailing southwesterly winds caused more cinders to accumulate on the opposite (northeastern) side of the volcano. Loess (windblown dust) is another aeolian feature at the monument. This material fills vesicles and cracks on lava flows. Loess-infilling serves as an informal dating method of lava flows and associated landscapes. Loess also plays a role in soil formation.
- K-T Boundary. Although Capulin Volcano National Monument does not contain the Cretaceous-Tertiary (“K-T”) boundary, the nearby exposure at Goat Hill may be of interest to visitors. This boundary marks a massive, worldwide extinction of an estimated 50% of all species, including dinosaurs, 66 million years ago.
Also see the park Geologic Resources Inventory Report for details on these and other volcanic features and process, as well as a discussion of resource management issues.
Geology Field Notes
Students and teachers of college-level (or AP) introductory geology or earth science teaching courses will find that each park's Geologic Resource Inventory report includes the Geologic History, Geologic Setting, and Geologic Features & Processes for the park which provides a useful summary of their overall geologic story. See Baseline Inventories, below.
Capulin Volcano National Monument is a part of the Great Plains Physiographic Province and shares its geologic history and some characteristic geologic formations with a region that extends well beyond park boundaries.
Geologic Resources Inventory
- Scoping summaries are records of scoping meetings where NPS staff and local geologists determined the park’s geologic mapping plan and what content should be included in the report.
- Digital geologic maps include files for viewing in GIS software, a guide to using the data, and a document with ancillary map information. Newer products also include data viewable in Google Earth and online map services.
- Reports use the maps to discuss the park’s setting and significance, notable geologic features and processes, geologic resource management issues, and geologic history.
- Posters are a static view of the GIS data in PDF format. Newer posters include aerial imagery or shaded relief and other park information. They are also included with the reports.
- Projects list basic information about the program and all products available for a park.
- Capulin Volcano—Natural Features and Ecosystems
- Capulin Volcano—Volcano Formation
- Capulin Volcano—Volcanic Fields
- Capulin Volcano—Park Home
- NPS—Volcanic Landforms: Extrusive Igneous
- NPS—Geologic Time
- NPS—Explore Regional Geology
Related ArticlesCapulin Volcano National Monument
National Park Service Geodiversity AtlasThe servicewide Geodiversity Atlas provides information on geoheritage and geodiversity resources and values within the National Park System. This information supports science-based geoconservation and interpretation in the NPS, as well as STEM education in schools, museums, and field camps. The NPS Geologic Resources Division and many parks work with National and International geoconservation communities to ensure that NPS abiotic resources are managed using the highest standards and best practices available.
For more information on the NPS Geodiversity Atlas, contact us.
Series: National Park Service Geodiversity Atlas
Last updated: October 24, 2019