National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science

Capulin Volcano National Monument

Geologic Resources Inventory Report

Natural Resource Report NPS/NRSS/GRD/NRR—2015/1031
ON THE COVER: Photograph of Capulin Volcano from the boca. Following eruption of First Series lava flows and 

Capulin Volcano, activity shifted to the boca on the western flank of the cinder cone. This view is looking east from 

the boca toward Capulin crater rim. Road cuts along Volcano Road can be seen just below the rim. Photograph by 

Matthew Zimmerer (MattZPhotography, www.mattzphotography.com [accessed 11 September 2015], used with 

permission), processed using Adobe Lightroom. 

THIS PAGE: Photograph looking west from Volcano Road on Capulin Volcano. Photograph by Dale L. Pate (taken on 

22 March 2010).
Capulin Volcano National Monument

Geologic Resources Inventory Report

Natural Resource Report NPS/NRSS/GRD/NRR—2015/1031

Katie KellerLynn 

Colorado State University Research Associate

National Park Service Geologic Resources Division

Geologic Resources Inventory

PO Box 25287

Denver, CO 80225

September 2015

U.S. Department of the Interior

National Park Service

Natural Resource Stewardship and Science 

Fort Collins, Colorado
ii

The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a 

range of reports that address natural resource topics. These reports are of interest and applicability to a broad audience 

in the National Park Service and others in natural resource management, including scientists, conservation and 

environmental constituencies, and the public. 

The Natural Resource Report Series is used to disseminate comprehensive information and analysis about natural 

resources and related topics concerning lands managed by the National Park Service. The series supports the 

advancement of science, informed decision-making, and the achievement of the National Park Service mission. The 

series also provides a forum for presenting more lengthy results that may not be accepted by publications with page 

limitations.

All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically 

credible, technically accurate, appropriately written for the intended audience, and designed and published in a 

professional manner. This report received informal peer review by subject-matter experts who were not directly 

involved in the collection, analysis, or reporting of the data.

Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and 

policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products 

does not constitute endorsement or recommendation for use by the U.S. Government. 

This report is available from the Geologic Resources Inventory website (http://go.nps.gov/gripubs), and the Natural 

Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). To receive this report in 

a format optimized for screen readers, please email irma@nps.gov.

Please cite this publication as:

KellerLynn, K. 2015. Capulin Volcano National Monument: Geologic resources inventory report. Natural Resource 

Report NPS/NRSS/GRD/NRR—2015/1031. National Park Service, Fort Collins, Colorado.

NPS 125/129746, September 2015
iii

Contents

Page

Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Products and Acknowledgments . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

GRI Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Geologic Setting and Significance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Geologic Features and Processes . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Volcanic Rocks and Volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Capulin Basalt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Raton-Clayton Volcanic Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Capulin Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Volcanic Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

View from Capulin Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Playa Lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Aeolian Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

K-T Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Paleontological Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Geologic Resource Management Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Slope Movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Aeolian Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Wind Energy Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Cave Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Cinder Mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Volcano Hazards and Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Geothermal Systems and Hydrothermal Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Geologic History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Raton Phase

(9.0 million–3.5 million years ago) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Clayton Phase

(3.0 million–2.2 million years ago) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Capulin Phase

(1.69 million–32,000 years ago) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Geologic Map Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Geologic Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Source Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

GRI GIS Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

GRI Map Posters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Map Unit Properties Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Use Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Additional References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Geology of National Park Service Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

NPS Resource Management Guidance and Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Climate Change Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
iv

Contents (continued)

Geological Surveys and Societies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

US Geological Survey Reference Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Appendix A: Scoping Participants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Appendix B: Geologic Resource Laws, Regulations, and Policies . . . . . . . . . . . . . . . . . . . . . . . . . 55

GRI Posters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .in pocket

Map Unit Properties Tables . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .in pocket

Page
v

Figures

Figure 1. Map of Capulin Volcano National Monument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2. Photograph of Nature Trail at Capulin Volcano National Monument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure 3. Geologic time scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Figure 4. Map of major volcanic fields in New Mexico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 5. Regional map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 6. Photograph of Capulin Basalt. Basalt covers the landscape of Capulin Volcano National Monument . . . . . . . . . . . . . . . . . . . 7

Figure 7. Schematic illustration of volcano types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 8. Map of Raton-Clayton volcanic field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 9. Schematic illustrations of the formation of inverted topography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 10. Photograph of cinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 11. Schematic illustration of a cinder cone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 12. Photographs of exposures along Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 13. Photograph of a bomb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 14. Photograph a block along Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 15. Satellite imagery of pressure ridges and cinder cone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 16. Photograph of lava lake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 17. Photograph of stone fireplace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 18. Photograph of a squeeze-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 19. Photograph of a tumulus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 20. Photograph of the Capulin Volcano vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 21. Panoramic views from Capulin Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 22. Satellite imagery with landmarks around Capulin Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 23. Panoramic view of Baby Capulin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 24. Photograph of Sierra Grande. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 25. Photograph of Capulin Volcano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 26. Photograph of the K-T boundary at Raton Pass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 27. Photographs of the K-T boundary at Goat Hill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 28. Photograph of storm-related damage along Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 29. Satellite imagery with locations of culverts along Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 30. Photograph of erosion along Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 31. Photograph of a cinder slide on Volcano Road. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 32. Photograph of a debris flow on Volcano Road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 33. Photograph of slope movements along Volcano Road. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 34. Photographs of Twin Mountain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 35. Maps of vent migration patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 36. Schematic illustration of volcano hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 37. Photograph of Towndrow Peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 38. Satellite imagery of Capulin phase volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 39. Panoramic views of Capulin crater and vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Page

Tables

Page

Table 1. Classification and characteristics of volcanic rocks . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Table 2. 40Ar/39Ar ages for Capulin and surrounding volcanoes . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 3. GRI GIS data layers of cavo_geology.mxd (volcanic features map of Capulin Volcano National Monument) . . . . . . . . . . . . . . . 40

Table 4. GRI GIS data layers of cvlf_geology.mxd (lava flow series of Capulin Volcano area) . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

vii

Executive Summary

The Geologic Resources Inventory (GRI) is one of 12 inventories funded by the National Park Service 

(NPS) Inventory and Monitoring Program. The Geologic Resources Division of the NPS Natural 

Resource Stewardship and Science Directorate administers the GRI. This report synthesizes discussions 

from a scoping meeting for Capulin Volcano National Monument (New Mexico) on 10 May 2011, 

which was held by the Geologic Resources Division to identify geologic resources of significance and 

geologic resource management issues, as well as determine the status of geologic mapping. It is a 

companion document to previously completed GRI GIS data.

● Volcanic Rocks and Volcanoes. Capulin Volcano 

and all the other volcanic features in Capulin 

Volcano National Monument are composed 

of basalt—an extrusive igneous rock with less 

than 52% silica. Geologists use silica content 

as a means for classifying volcanic rocks. The 

percentage of silica influences many properties of 

magma, including viscosity (internal friction) and 

explosiveness, as well as the type of volcano that 

forms during an eruption. Capulin Volcano is a 

classic example of a cinder cone.

About 55,000 years ago, Capulin Volcano erupted with 

molten rock launched thousands of feet into the air. 

The rain back to earth of cooling cinders and other 

pyroclastic materials, such as ash and bombs, formed 

the volcano. Although extinct today and unlikely to 

erupt again, Capulin Volcano is dramatic evidence of 

the spectacular volcanic events that formed the RatonClayton volcanic field of northeastern New Mexico. 

Much of the attraction of Capulin Volcano is a road that 

leads to the volcano rim, providing outstanding views of 

the surrounding wide-open country of the High Plains 

and the Raton-Clayton volcanic field. The road is called 

“Volcano Road.” In addition, five trails wind through 

the volcanic terrain at the monument. 

This GRI report compiles geologic information for 

Capulin Volcano National Monument and discusses 

management issues related to the geologic features 

contained within its boundaries. The report was 

written for resource managers to support scienceinformed decision making. It may also be useful for 

interpretation. The report was prepared using available 

geologic information, and the NPS Geologic Resources 

Division conducted no new fieldwork in association 

with its preparation. Chapters of the report discuss 

distinctive geologic features and processes, highlight 

geologic issues facing resource managers, describe the 

geologic history leading to the present-day landscape, 

and provide information about the GRI GIS data set. 

Two posters (in pocket) illustrate these data: one is a 

volcanic features map of the monument; the other is a 

map showing the lava flow series in the Capulin Volcano 

area. The Map Unit Properties Table (in pocket) 

summarizes report content for each geologic map unit. 

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.
viii

● 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. 

● Paleontological Resources. To date, no 

paleontological resources have been documented 

in Capulin Volcano National Monument. The 

discovery of tree molds or pack rat middens is 

possible, however. Tree molds (trace fossils formed 

by the envelopment of a tree by a lava flow) occur 

in some volcanic settings in the National Park 

System. Pack rat middens are a potential source 

of paleontological and paleoenvironmental 

information.

Geologic resource management issues identified during 

the GRI scoping meeting included the following:

● Volcano Road. First constructed in 1925, Volcano 

Road is a distinctive feature and an important 

part of Capulin Volcano National Monument’s 

cultural landscape. It is significant for the scientific, 

educational, and public enjoyment opportunities it 

provides. However, it also has the greatest impact 

on the monument’s geologic resources, specifically 

the cinder cone. The road’s impervious surface 

and many of its culverts concentrate runoff which 

erodes, sometimes severely, the sides of the volcano. 

According to the NPS natural resource condition 

assessment for the monument, Volcano Road and 

its effects on Capulin Volcano have resulted in a 

condition of “significant concern” and “a declining 

trend.” In 2012, a Federal Highway Administration 

project incorporated erosion control measures and 

repaired road shoulders, drainage structures, and 

eroded hill slope areas. 

● Erosion. Erosion is arguably the greatest threat to 

the geologic resources at Capulin Volcano National 

Monument. A primary gap in understanding is the 

degree and severity of unnatural as opposed to 

natural erosion. Existing information related to soil 

erosion at Capulin Volcano National Monument 

includes a NPS Soil Resources Inventory (SRI) and 

a rapid soil assessment and trip report. In addition 

to Volcano Road, erosion is affecting sections of the 

Lava Flow Trail, Crater Rim Trail, and a fire road in 

the southern part of the monument.

● Slope Movements. Slope movements are ongoing 

at Capulin Volcano National Monument and cause 

cinders to slide, debris flows to form, and entire 

sections of slopes to fail. These processes are a 

particular concern along Volcano Road. A data 
ix

need at the monument is a better understanding 

of the triggers and timing of these gravity-driven 

events.

● Aeolian Processes. Wind is a primary geologic 

agent at Capulin Volcano National Monument. 

Wind transports cinders onto Volcano Road, which 

is a concern for maintenance and safety. Dust 

storms are rare now that grazing has stopped within 

the monument but can take place, primarily in 

March and April. Construction sites are sources of 

windblown dust.

● Wind Energy Development. Wind energy 

development is a concern for the preservation 

of the monument’s viewshed. The National Park 

Service uses a combined technical and policy 

approach to manage and protect park resources and 

values as renewable energy potential is identified 

and developed near NPS areas.

● Cave Management. An inventory of caves (as 

geologic resources) is needed at Capulin Volcano 

National Monument. No cave management plan 

has been completed to date. The NPS Geologic 

Resources Division has expertise to assist with the 

preparation of a cave management plan.

● Cinder Mining. Cinder mining has occurred 

in the vicinity of Capulin Volcano National 

Monument, for example, at Twin Mountain—a 

cinder cone northeast of Capulin Volcano. The 

monument contains three “test pits,” which 

scoping participants identified but did not deem 

in need of restoration. Monument managers may 

wish to include these sites in the NPS Abandoned 

Mineral Lands (AML) database. The NPS Geologic 

Resources Division (GRD) manages the AML 

database and has expertise to assist with restoration 

projects, if needed in the future.

● Volcano Hazards and Risk. Volcanism in the 

Raton-Clayton volcanic field began about 9 million 

years ago and no evidence suggests that it has 

ended. An eruption in the future is likely, though 

an eruption at an existing volcano, such as Capulin 

Volcano, is unlikely. Rather, a new batch of magma 

will probably extrude through a new vent, possibly 

forming a new cinder cone. In addition to cone 

building, other potential hazards include localized 

ash fall, earthquakes (as magma rises to the surface), 

volcanic gases, lava eruptions (flows), volcanic 

projectiles, and wildfires.

● Geothermal Systems and Hydrothermal 

Features. Capulin Volcano National Monument 

is not known for its geothermal resources or 

hydrothermal features and is not included on 

the list of 16 parks that are designated under the 

Geothermal Steam Act of 1970, as amended in 

1988. However, during the 2011 GRI scoping 

meeting, participants discussed a “hot vent” 

near the maintenance building, which may 

be an indicator of heat transfer. No known 

documentation exists. Investigating this “vent” may 

be a project for a Geoscientist-In-the-Parks (GIP) 

participant. This program is administered by the 

NPS Geologic Resources Division.

xi

Products and Acknowledgments

The NPS Geologic Resources Division partners with institutions such as Colorado State University, 

the US Geological Survey, state geological surveys, local museums, and universities to develop GRI 

products. This chapter describes those products and acknowledges contributors to this report.

GRI Products

The objective of the Geologic Resources Inventory is 

to provide geologic map data and pertinent geologic 

information to support resource management and 

science-informed decision making in more than 

270 natural resource parks throughout the National 

Park System. To realize this objective, the GRI team 

undertakes three tasks for each natural resource park: 

(1) conduct a scoping meeting and provide a summary 

document, (2) provide digital geologic map data in a 

geographic information system (GIS) format, and (3) 

provide a GRI report (this document). These products 

are designed and written for nongeoscientists.

Scoping meetings bring together park staff and geologic 

experts to review and assess available geologic maps, 

develop a geologic mapping plan, and discuss geologic 

features, processes, and resource management issues 

that should be addressed in the GRI report. Following 

the scoping meeting, the GRI map team converts the 

geologic maps identified in the mapping plan to digital 

geologic map data in accordance with the GRI data 

model. After the map is completed, the GRI report team 

uses these data, as well as the scoping summary and 

additional research, to prepare the GRI report. 

The compilation and use of natural resource 

information by park managers is called for in the 1998 

National Parks Omnibus Management Act (section 

204), 2006 National Park Service Management 

Policies, and the Natural Resources Inventory and 

Monitoring Guideline (NPS-75). The “Additional 

References” chapter and Appendix B provide links to 

these and other resource management documents and 

information.

Additional information regarding the GRI, including 

contact information, is available at http://go.nps.gov/gri. 

The current status and projected completion dates of 

products are available at http://go.nps.gov/gri_status.

Acknowledgments

Thanks very much to Stephanie O’Meara (Colorado 

State University), Michael Ort (Northern Arizona 

University), and Mike Timmons (New Mexico Bureau 

of Geology and Mineral Resources) for interpreting 

and verifying the locations of volcanic vents for 

use in the GRI GIS data set for Capulin Volcano 

National Monument. Additionally, thanks to Matthew 

Smith (Western Archeological and Conservation 

Center) for tracking down information about caves 

at the monument. Also, thanks very much to Trista 

Thornberry-Ehrlich (Colorado State University) for 

developing graphics and Matthew Zimmerer (New 

Mexico Bureau of Geology and Mineral Resources) 

for sharing photographs used as figures in this report. 

Gina D’Ambrosio (New Mexico Bureau of Geology 

and Mineral Resources) provided photographs from the 

bureau for use in this report. 

Review

Lynn Cartmell (Capulin Volcano National Monument)

Jason Kenworthy (NPS Geologic Resources Division)

Dale L. Pate (NPS Geologic Resources Division)

Matthew Zimmerer (New Mexico Bureau of Geology 

and Mineral Resources)

Editing

Rebecca Port (NPS Geologic Resources Division)

Report Formatting and Distribution

Jason Kenworthy (NPS Geologic Resources Division)

Rebecca Port (NPS Geologic Resources Division)

Source Maps

Rebecca Richman (Student Conservation Association)

William O. Sayre (College of Santa Fe)

Michael H. Ort (Northern Arizona University)

GRI GIS Data Production

Stephanie O’Meara (Colorado State University)

GRI Poster Design

Kari Lanphier (Colorado State University)

GRI Poster Editing

Georgia Hybels (Colorado State University)

Rebecca Port (NPS Geologic Resources Division)

Jason Kenworthy (NPS Geologic Resources Division)

1

Geologic Setting and Significance

This chapter describes the regional geologic setting of Capulin Volcano National Monument and 

summarizes connections among geologic resources, other park resources, and park stories.

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 is also one of the most 

accessible volcanoes in North America. Only 

two other cones—Lava Butte and Pilot Butte, 

both near Bend, Oregon—have paved roads to 

their summits (Mathis 1999). Volcano Road at 

the monument spirals around the cinder cone 

to a parking lot at the crater rim. 

Five trails also lead around and through the 

volcanic terrain at the monument (fig. 1). 

First, Crater Rim Trail is a paved, 1.6 km (1 mi) 

loop around the top of the volcano. The trail 

supplies the equivalent of an aerial view of the 

morphologic features of nearby lava flows and 

volcanoes, as well as gives panoramic views 

of the entire Raton-Clayton volcanic field, 

of which Capulin Volcano is a part. Wayside 

exhibits along the trail provide information 

about the surrounding physiographic features. 

Second, Crater Vent Trail is a paved 0.3 km 

(0.2 mi) route descending to the vent at the bottom of 

the crater. This trail provides an opportunity to hike 

into a volcano. The trail is a good place to imagine 

events that took place 55,000 years ago when cinders 

erupted into the air and fell back down around the vent 

to form the volcano. Third, Lava Flow Trail at the base 

of the volcano is an unimproved, 1.6 km (1 mi) loop 

that goes out onto one of the lava flows, specifically 

the “Second Series” lava flows (see lava flow series 

map, in pocket). Fourth, Nature Trail is a figure-eight, 

wheelchair-accessible loop adjacent to the visitor center 

(fig. 2). The trail has stops that discuss wildlife, plant 

life, and geology. Fifth, Boca Trail is an unimproved, 3 

km (2 mi) journey through the mouth of the volcano 

at the western base of the cinder cone; “boca” means 

“mouth” in Spanish. Richman (2010)—the source of the 

GRI GIS data set—mapped Capulin Volcano’s complex 

boca in detail (see volcanic features map, in pocket; and 

“Geologic Map Data” chapter). 

Four major lava flows are associated with Capulin 

Volcano. The flows cover about 40 km2

 (16 mi2) and 

extend well beyond the monument boundary (see lava 

flow series map, in pocket). The monument contains 

the cinder cone, boca, and a portion of each of these 

flows (see Map Unit Properties Table and posters, in 

pocket). Sayre and Ort (1999) delineated the flows into 

four series. First Series lava flows were extruded before 

and during the cone-building eruption. Later, lava flows 

spread southeast (Second Series), southwest (Third 

Series), and north (Fourth Series) of the cinder cone. 

Figure 1. Map of Capulin Volcano National Monument. The 

monument encompasses 320.86 ha (792.84 ac) of all federal land. 

Volcano Road spirals to the top of the volcano with an area for 

parking at the rim. Five trails within the monument lead around 

and through the volcanic terrain: Crater Vent Trail, Crater Rim 

Trail, Lava Flow Trail, and Boca Trail (delineated here); Nature 

Trail is adjacent to the visitor center. National Park Service graphic 

available at http://www.nps.gov/hfc/cfm/carto-atoz.cfm (accessed 10 

October 2014). 
2

These later lava flows emerged from vents in the boca 

on the western side of the volcano.

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 volcanic field spans roughly the same 

distance north to south (see fig. 8 in “Geologic Features 

and Processes” chapter). 

The Raton-Clayton volcanic field erupted 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) (Stroud 1997; Zimmerman 

2015). Formally named rock units—Raton, Clayton, and 

Capulin basalts—correlate to these phases (Scott et al. 

1990).

The eruption of Capulin Volcano occurred about 

55,000 years ago (Pleistocene Epoch; fig. 3) 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.

The Raton-Clayton volcanic field occurs on the 

Jemez lineament (fig. 4)—a southwest-to-northeast–

oriented zone of weakness in Earth’s crust where 

recent (Pliocene–Pleistocene epochs; fig. 3) volcanic 

activity is concentrated. In New Mexico, this swath of 

volcanism incorporates the Raton-Clayton volcanic 

field, Ocaté volcanic field (see GRI report about Fort 

Union National Monument by KellerLynn 2012b), 

Mount Taylor, and the Zuni-Bandera volcanic field 

(see GRI report about El Malpais National Monument 

by KellerLynn 2012a). The most spectacular volcanic 

activity occurred where the Rio Grande rift intersects 

the lineament at Valles caldera (see GRI report about 

Bandelier National Monument by KellerLynn 2015). 

At this location, two huge, caldera-forming eruptions 

occurred 1.61 million and 1.25 million years ago, 

emplacing the famous Bandelier Tuff that dominates 

the landscape at Bandelier National Monument and is a 

“must see” for volcano enthusiasts.

The entrance to the Capulin Volcano National 

Monument is from New Mexico Highway 325, 5 km (3 

mi) north of the town of Capulin (fig. 5). Highway 325 

intersects US highway 64/87, which runs diagonally 

across the Raton-Clayton volcanic field. The High 

Plains environment, which is neither complicated by 

mountainous terrain nor obscured by forests, allows for 

broad views of volcanic features for travelers along the 

highway (Stormer 1994). In the past, the volcano served 

as a landmark along the Santa Fe Trail. The Cimarron 

Route of the trail runs to the south of the monument; 

the Mountain Route runs to the west (fig. 5). 

On 9 August 1916, President Woodrow Wilson 

proclaimed Capulin Mountain as a national monument, 

applying the 1906 Act for the Preservation of American 

Antiquities (“Antiquities Act”). This milestone 

legislation gives the president the power to set aside 

and protect as a national monument any federal lands 

deemed historically or scientifically important. The 

proclamation states that Capulin Mountain is “a striking 

Figure 2. Photograph of Nature Trail at Capulin Volcano 

National Monument. The wheelchair-accessible trail 

adjacent to the visitor center provides opportunities to 

see wildlife, plant life, and geologic features. Note the 

tumulus (mound of lava on the surface of a lava flow) 

on the right. Jose Butte is in the background. National 

Park Service photograph by Ally Buccanero available at 

http://www.nps.gov/cavo/planyourvisit/accessibility.htm

(accessed 10 October 2014).
3

Formation of the Earth

Eon Era Period Epoch MYA Phanerozoic Proterozoic Archean Hadean Cenozoic (CZ) Mesozoic (MZ) Paleozoic (PZ)

Quaternary

(Q)

Neogene

(N)

Cretaceous (K)

Jurassic (J)

Triassic (TR)

Permian (P)

Pennsylvanian (PN)

Mississippian (M)

Devonian (D)

Silurian (S)

Ordovician (O)

Cambrian (C)

Precambrian (PC, X, Y, Z)

Holocene (H)

Pleistocene (PE)

Pliocene (PL)

Miocene (MI)

Oligocene (OL)

Eocene (E)

Paleocene (EP)

2.6

5.3

23.0

33.9

56.0

145.0

201.3

298.9

323.2

358.9

419.2

443.8

485.4

2500

4000

4600

66.0

541.0

Age of Mammals Age of Reptiles Age of Amphibians Fishes Marine Invertebrates

Modern humans 

Spread of grassy

 ecosystems

Extinction of large

 mammals and birds 

Early primates 

Placental mammals 

Early flowering plants 

Dinosaurs diverse and

 abundant

First dinosaurs; first mammals

Flying reptiles

Sharks abundant

First reptiles

Mass extinction

First amphibians

First forests (evergreens)

First land plants

Mass extinction

Primitive fish

Trilobite maximum

Rise of corals

Complex multicelled organisms 

Simple multicelled organisms 

Early bacteria and algae

 (stromatolites)

Origin of life

0.01

Mass extinction

Paleogene

(PG)

Tertiary (T)

Basin and Range extension (W)

Elko Orogeny (W)

Breakup of Pangaea begins

Sonoma Orogeny (W)

Supercontinent Pangaea intact

Ouachita Orogeny (S)

Ancestral Rocky Mountains (W)

Antler Orogeny (W)

Acadian Orogeny (E-NE)

Taconic Orogeny (E-NE)

Extensive oceans cover most of 

 proto-North America (Laurentia)

First iron deposits

Abundant carbonate rocks

Formation of Earth’s crust

Oldest known Earth rocks

Formation of early supercontinent

Grenville Orogeny (E)

Cascade volcanoes (W)

Ice age glaciations;

 glacial outburst floods

Columbia River Basalt eruptions (NW)

Linking of North and South 

 America (Isthmus of Panama)

Laramide Orogeny ends (W)

Nevadan Orogeny (W)

Sevier Orogeny (W)

Laramide Orogeny (W)

Alleghany (Appalachian)

 Orogeny (E)

Supercontinent rifted apart

Western Interior Seaway (W)

Early shelled organisms

252.2 Mass extinction

 Life Forms North American Events 

Mass extinction

Coal-forming swamps

Figure 3. Geologic time scale. The divisions of the geologic time scale are organized stratigraphically, with the oldest 

divisions at the bottom and the youngest at the top. Capulin Volcano National Monument is entirely covered by a 

single rock formation, Capulin Basalt. All volcanic activity at the monument took place during the Pleistocene Epoch, 

about 55,000 years ago. Volcanic activity in the Raton-Clayton volcanic field began during the Miocene Epoch, about 9 

million years ago. GRI map abbreviations for each time division are in parentheses. Compass directions in parentheses 

indicate the regional locations of events. Boundary ages are millions of years ago (MYA). National Park Service graphic 

using dates from the International Commission on Stratigraphy (http://www.stratigraphy.org/index.php/ics-charttimescale; accessed 6 August 2015).
4

example of recent extinct volcanoes and is of great 

scientific and especially geologic interest.” 

On 31 December 1987, the monument was redesignated “Capulin Volcano National Monument” to 

highlight its volcanic origin. In this report, the use of 

“Capulin Volcano” rather than “Capulin Mountain” 

reflects this change and volcanic significance. As a 

matter of interest and clarification, the word “capulin” 

is not related to volcanic processes, rather it is Spanish 

for chokecherry (Prunus virginiana), which grows well 

in the region and is present in the monument, including 

the crater of Capulin Volcano.
5

Figure 4 (facing page). Map of major volcanic fields in New Mexico. Capulin Volcano National Monument is in the 

Raton-Clayton volcanic field in northeastern New Mexico. This and many other volcanic fields lie on the Jemez 

lineament, a zone of crustal weakness and concentrated volcanism that runs across the state. The National Park System 

is well represented along the Jemez lineament: El Malpais National Monument and El Morro National Monument are 

part of the Zuni–Bandera volcanic field. Bandelier National Monument is part of the Jemez Mountains volcanic field; 

Valles caldera lies near the center of this field. Fort Union National Monument is surrounded by the Ocaté volcanic 

field. The north–south-oriented Rio Grande rift intersects the Jemez lineament near Valles caldera. Earth’s crust is 

pulling apart along this rift. Petroglyph National Monument lies in the Rio Grande rift near Albuquerque. New Mexico 

Bureau of Geology and Mineral Resources graphic, modified by Philip Reiker (NPS Geologic Resources Division).

Figure 5. Regional map. Capulin Volcano National Monument is in the northeastern corner of New Mexico. US highway 

64/87 provides a scenic drive through this part of the country. When the Santa Fe Trail was in use as a transportation 

route (1821–1880), Capulin Volcano served as a landmark. The Mountain Route of the Santa Fe Trail is north of the 

monument; the Cimarron Route is south of the monument. National Park Service graphic, available at

http://www.nps.gov/hfc/cfm/carto-atoz.cfm (accessed 10 October 2014).

7

Geologic Features and Processes

This chapter describes noteworthy geologic features and processes in Capulin Volcano National 

Monument.

During the 2011 scoping meeting (see 

KellerLynn 2011) participants (see 

Appendix A) identified the following 

geologic features and processes:

● Volcanic Rocks and Volcanoes

● Capulin Basalt

● Raton-Clayton Volcanic Field

● Capulin Volcano

● Volcanic Features

● Age of Capulin Volcano

● View from Capulin Volcano

● Playa Lakes

● Aeolian Features

● K-T Boundary

● Paleontological Resources

Volcanic Rocks and Volcanoes

A single, formally named, rock unit—

Capulin Basalt (see “Capulin Basalt” 

section)—covers Capulin Volcano National Monument 

(fig. 6). All volcanic features within the monument are 

composed of Capulin Basalt. Capulin Basalt originated 

as magma (molten rock) beneath the surface, traveled 

through preexisting rocks of Earth’s crust, then 

extruded out of vents (openings at Earth’s surface 

through which magma erupts or volcanic gases are 

emitted). Once at the surface, magma, now referred to 

as lava, formed volcanoes, lava flows, and other volcanic 

features (see “Volcanic Features” section). 

Basalt is an extrusive igneous rock, which by definition 

contains 52% or less of silica (silicon dioxide, SiO2

) 

(table 1). The amount of silica assigned to a category 

of volcanic rock may vary depending on whether 

rhyodacite and basaltic andesite, for example, are 

included in an investigation’s classification scheme. 

The amount of silica influences many properties of 

magma, including viscosity (internal friction) and 

explosiveness. In general, lavas with more silica are 

more viscous and more explosive. Flows of andesite 

(57%–63% SiO2

) and dacite (63%–68% SiO2), for 

example, tend to be thick and sluggish, traveling 

only short distances from a vent. Lavas of dacite and 

rhyodacite (68%–72% SiO2

) commonly squeeze out 

of a vent to form irregular mounds or lava domes. Red 

Mountain, which is composed of the formally named 

Red Mountain Dacite (Collins 1949; Scott et al. 1990), is 

a dome. This dome sits atop Johnson Mesa, northwest 

of Capulin Volcano. By contrast, basalt forms lava 

flows that spread out in broad, thin sheets up to several 

kilometers wide. Repeated eruptions of basaltic flows 

in a volcanic field may build a shield volcano (fig. 7). 

Individual basaltic eruptions commonly form cinder 

cones, such as beautiful Capulin Volcano (see “Capulin 

Volcano” section). Notably, eruptions of basalt, though 

lower in silica content than andesite or dacite, can be 

spectacular, with fire fountains jetting upwards to 900 m 

(3,000 ft) above the ground. These features are typical 

of Hawaiian–style basaltic volcanism (Dunbar 2010; see 

GRI report about Hawaii Volcanoes National Park by 

Thornberry-Ehrlich 2009). 

The most explosive volcanoes on Earth are generally 

rhyolitic (>72% SiO2

). After an eruption of rhyolite, 

Figure 6. Photograph of Capulin Basalt. Basalt covers the landscape of 

Capulin Volcano National Monument. The summit of Capulin Volcano 

at 2,494 m (8,182 ft) above sea level appears in the background of the 

photograph. National Park Service photograph available at

http://www.nps.gov/storage/images/cavo/Webpages/originals/361.jpg

(accessed 6 October 2014).
8

volcano edifices often do not look like volcanoes 

because the eruptions are so explosive that the volcano 

ends up collapsing in on itself, forming a caldera. The 

eruption that formed Valles caldera was this type (see 

GRI report about Bandelier National Monument 

by KellerLynn 2015). It is the oldest of three young 

caldera-forming volcanoes in the United States; the 

others are Yellowstone in Wyoming and Long Valley in 

California (US Geological Survey 2014). In addition, 

the Bursum and Gila Cliff Dwellings calderas, which 

surround Gila Cliff Dwellings National Monument in 

New Mexico (see GRI report by KellerLynn 2014a), are 

the result of rhyolitic explosions about 28 million years 

ago.

The four major types of volcanoes are (1) cinder cones, 

(2) shield volcanoes, (3) stratovolcanoes (also called 

composite volcanoes), and (4) lava domes (fig. 7). Of 

interest for the National Park System, Lassen Volcanic 

National Monument in California 

contains all four primary types of 

volcanoes (see GRI report by KellerLynn 

2014b). A combination of physical 

attributes—such as size, shape, slope 

angle, type and composition of volcanic 

materials, and eruption style—determine 

the type of a particular volcano. These 

types provide a system for classification 

and a means for understanding and 

communication. In reality, volcanoes 

occur in a continuum of sizes and shapes 

and have a variety of origins (Michael 

Clynne, US Geological Survey, research 

geologist, written communication, 21 

November 2013). 

Capulin Basalt

Capulin Volcano National Monument is 

composed of a single rock unit—Capulin 

Basalt—which Collins (1949) originally 

mapped and identified, Baldwin and 

Muehlberger (1959) mapped in greater 

detail, and Scott et al. (1990) formally 

Table 1. Classification and characteristics of volcanic rocks

Rock Name: Rhyolite Rhyodacite Dacite Andesite Basaltic 

Andesite

Basalt

Silica (SiO2) 

content1 >72% 68%–72% 63%–68% 57%–63% 52%–57% <52%

Color

Lighter Darker

Viscosity of 

magma

Thick

(less mobile flows)

Fluid

(more mobile flows)

Typical style of 

eruption Explosive Effusive

Eruption 

temperature2

Cooler, 800°C 

(1,500°F)

Hotter, 1,160°C 

(2,120°F)

1

Silica percentages from Clynne and Muffler (2010). 2Eruption temperatures from Price (2010).

Low-Silica

Lava

High-Silica Lava

10’s to over 100 miles 

(d) Lava

Dome

< 2 miles 

Slope < 8°

1 to 10 miles

< 1 mile 

(c) Stratovolcano

(b) Cinder

Cone

(a) Shield Volcano

10° - 20°

30°

20°

Figure 7. Schematic illustration of volcano types. The size and shape of 

volcanoes are influenced by the amount of silica and gas in the erupting 

lava. Low-silica lavas, such as basalt, produce broad shield volcanoes (a). 

If basaltic lava has a lot of gas, a central vent may erupt like a fire hose, 

forming a cinder cone (b). Higher silica lavas, andesite to rhyolite, form 

composite volcanoes, also called “stratovolcanoes” (c). Lava domes form 

around a vent that erupts high-silica lava such as dacite (d). Graphic by 

Jason Kenworthy (NPS Geologic Resources Division) after Lillie (2005, 

figure 2.18).
9

named. Technically, Capulin Basalt is a “trachybasalt” 

(Sayre and Ort 1999), meaning it has more abundant 

alkali elements, such as sodium and potassium, than 

true basalt. For simplicity, this report refers to the 

volcanic rock of Capulin Volcano as “basalt.”

Capulin Basalt contains a relatively high percentage 

of silica for a basalt (50%–55%; Sayre and Ort 1999). 

It owes this higher amount to the presence of quartz 

grains. The mineral quartz, which is composed entirely 

of silica, was derived from sedimentary rocks (e.g., 

Dakota Sandstone) that underlie Capulin Volcano. As 

the volcano erupted, magma traveled through these 

rocks before reaching the surface, picking up silica on 

the way. 

The presence of Dakota Sandstone xenoliths (foreign 

rock fragments) and xenocrysts (foreign crystals, much 

smaller than xenoliths) is a characteristic feature of 

Capulin Basalt at the monument and surrounding area 

(Sayre and Ort 1999). Xenoliths may have come from 

the sides of a magma chamber, walls of an erupting lava 

conduit, or the base of a lava flow. Xenocrysts did not 

crystallize from the host magma and may be fragments 

of xenoliths. Xenoliths and xenocrysts can provide 

important information about the composition of Earth’s 

mantle, which is generally inaccessible. The ones in 

Capulin Basalt, however, are from the upper crust 

(KellerLynn 2011). 

Raton-Clayton Volcanic Field

Capulin Volcano National Monument is part of 

the large, long-lived Raton-Clayton volcanic field, 

which is mostly in northeastern New Mexico but also 

southeastern Colorado and the panhandle of Oklahoma 

(fig. 8). Notably, Mesa de Maya (Black Mesa), which 

erupted during the Clayton phase (Luedke and Smith 

1978), is in Colorado, New Mexico, and Oklahoma. The 

mesa is the highest point in Oklahoma, 1,516 m (4,973 

ft) above sea level. 

The 20,000-km2 (8,000-mi2) volcanic field has been 

active episodically for the past 9 million years. Using 

petrology, geochemistry, and both relative and isotopic 

dating methods, investigators have divided the field’s 

volcanic activity into 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). 

The Capulin phase includes the eruption that created 

Capulin Volcano (see “Geologic History” chapter).

Most of the volcanoes that were active in the Raton 

phase are on the western side of the volcanic field near 

the town of Raton. The lava flows and volcanoes of the 

Clayton phase span north to south, from Mesa de Maya 

in Colorado to the Yates flows south of Gladstone. 

Capulin phase features are clustered in the central part 

of the field in the vicinity of the towns of Capulin and 

Folsom (fig. 8).

The Raton-Clayton volcanic field consists of an 

estimated 125 volcanic vents (Dunbar 2005). These 

vents extruded primarily basaltic lava and produced 

mainly lava flows and cinder cones. One of the 

distinctive characteristics of the Raton-Clayton volcanic 

field is the presence of lavas with silica contents as 

low as 35% (Stormer 1994). The field also contains 

volcanoes, such as Sierra Grande, that erupted andesite, 

dacite, and rhyodacite; that is, lavas with up to 70% 

silica (Aubele and Crumpler 2001). This range of silica 

compositions is noteworthy, and the Raton-Clayton 

volcanic field is arguably the most chemically and 

mineralogically diverse volcanic field in the United 

States (Stormer 1994).

Another interesting characteristic of the Raton-Clayton 

volcanic field is its low volumetric eruption rate, which 

is interpreted as evidence for relatively small amounts 

of melting in the underlying mantle over extended 

periods of time (hundreds of thousands to millions 

of years) (Crumpler et al. 1992; Aubele and Crumpler 

2001). As a result, discrete batches of magma worked 

their way to the surface, ultimately resulting in a series 

of isolated eruptions that are petrologically unrelated to 

surrounding eruptions (Aubele and Crumpler 2001).

Inverted topography is another notable characteristic 

of the Raton-Clayton volcanic field (fig. 9). Lava flows, 

particularly those from the Raton phase, initially spread 

down river valleys (or other topographic lows) before 

solidifying. The valley walls (or other topographic 

highs) were composed of softer sedimentary rock—

such as the Raton Formation (see “K-T Boundary” 

section) and the Ogallala Formation (composed of 

sediments shed from the uplifting Rocky Mountains)—

and eroded more quickly than the harder lava in the 

valleys. Additionally, the resistant cap of lava protected 

the softer, underlying rock from wind and rain erosion. 

As a result, valleys into which the lava once flowed 
10

Figure 8. Map of Raton-Clayton volcanic field. The volcanic field, which is primarily in New Mexico but also has vents 

and/or lava flows in Colorado and Oklahoma, erupted episodically in three phases: Raton (9.0 million–3.5 million years 

ago), Clayton (3.0 million–2.2 million years ago), and Capulin (1.69 million–32,000 years ago). Basalt was deposited 

during each of these phases. Capulin Volcano erupted 55,000 ± 2,000 years ago during the Capulin phase. Sierra 

Grande—which is the largest volcano in the volcanic field—erupted 3.8 million–2.6 million years ago, overlapping 

in time with the Raton and Clayton phases. Andesite erupted at Sierra Grande. The formally named Red Mountain 

Dacite, which occurs in scattered lava domes such as Red Mountain, Green Mountain, and Palo Blanco, was deposited 

about 7 million years ago during the Raton phase. Graphic by Trista Thornberry-Ehrlich (Colorado State University) 

after Luedke and Smith (1978, plate 2), Crumpler and Audele (2008, online map), and Price (2010, p. 315). Silica range 

content is from Luedke and Smith (1978, plate 2).
11

now stand as high mesas (fig. 9). These lava-capped 

mesas include Johnson, Bartlett, Barella, Horse, Kiowa, 

and Kelleher mesas, and Mesa Larga and Mesa de 

Maya or Black Mesa (Aubele and Crumpler 2001). 

Several of these are visible from the summit of Capulin 

Volcano (see “View from Capulin Volcano” section). 

To the northwest, Johnson Mesa is capped by an 

approximately 8-million-year-old lava flow. Mesa de 

Maya is covered by 5-million-year-old lava and marks 

the northeastern margin of the volcanic field (fig. 8).

Capulin Volcano

“Cinder cones,” as the name suggests, are conical hills 

built from fragments of ejected lava called cinders 

(fig. 10). In the scheme of classic volcano types (fig. 

7), cinder cones are relatively small, usually less than 

300 m (1,000 ft) high. Capulin Volcano exceeds this 

general range by about 90 m (300 ft). In terms of 

geologic time, the formation of cinder cones happens 

quickly. Capulin Volcano, for example, built up over a 

period of weeks to years (Sayre and Ort 1999). During 

the eruption, cinders fountained high into the air, 

perhaps as high as 500 m (1,600 ft), and fell back to the 

ground around the vent, creating a pile of cinders and 

other pyroclastic material (rock fragments formed by 

volcanic explosion or aerial expulsion from a vent). 

Because unconsolidated pyroclastic materials such 

as cinders maintain a high angle of repose (30°–40°), 

volcanoes of this type have very steep slopes. Where 

the buildup of cinders exceeds the angle of repose, they 

avalanche downslope, creating a layered deposit (fig. 

11). The inclined layers that make up Capulin Volcano 

are beautifully exposed along Volcano Road (fig. 12). 

Each layer represents an episode in the cone-building 

eruption.

Although mostly composed of cinders, the deposits 

of Capulin Volcano contain other pyroclasts such as 

ash (fine-grained material), pumiceous material (with 

vesicles [“gas bubbles”]), bombs (viscous material, 

9 million years ago

Today

Figure 9. Schematic illustrations of the formation of 

inverted topography. Many of the lava flows in the 

Raton-Clayton volcanic field initially occupied stream 

valleys or other topographically low areas (9 million 

years ago, lower graphic). The hardened lava was 

more resistant to erosion than the valley walls, and it 

protected the underlying soft sandstone and shale from 

wind and rain erosion (middle graphic). Today, stream 

valleys in which the lava once flowed stand as high 

mesas above modern valleys (upper graphic). Graphic by 

Trista Thornberry-Ehrlich after Muehlberger et al. (2005, 

p. 4).

Figure 10. Photograph of cinders. Capulin Volcano 

is composed primarily of cinders—glassy, vesicular, 

pyroclastic fragments that explode from a vent then 

fall to the ground in an essentially solid condition. The 

large, triangular, red cinder (arrow) is approximately 

4 cm (1.5 in) long. Photograph by Katie KellerLynn 

(Colorado State University).
12

Crater

Pyroclastic layers

Central vent filled

with rock fragments

Figure 11. Schematic 

illustration of a cinder cone. 

Cinder cones are built from 

ejected lava fragments. 

Inclined pyroclastic layers show 

where the angle of repose was 

exceeded and cinder tumbled 

down the slope. Most cinder 

cones have a bowl-shaped 

crater at the summit. Graphic 

by Trista Thornberry-Ehrlich 

(Colorado State University) 

after Lutgens and Tarbuck 

(1992, figure 4.9).

Figure 12. Photographs of 

exposures along Volcano Road. 

During the cone-building 

eruption, layer upon layer of 

cinders and other pyroclastic 

material erupted into the air 

and fell to the surface around 

a central vent, constructing 

the cinder cone. Thin layers 

of ash separate the layers of 

cinders. Top: US Geological 

Survey photograph available 

at http://3dparks.wr.usgs.

gov/cavo/html2/capu21.htm

(accessed 2 October 2014). 

Bottom: National Park Service 

photograph by Ally Buccanero 

available at

http://www.nps.gov/cavo/

planyourvisit/auto-touring.htm

(accessed 10 October 2014).
13

greater than 64 mm [2.5 in] across, ejected then shaped 

while in flight; fig. 13), and blocks (material greater than 

64 mm [2.5 in] across, ejected in a solid state; fig. 14). 

Bombs were deposited up to 1 km (0.6 mi) from the 

vent. Pullouts on Volcano Road are excellent places 

to see bombs that landed on cinder beds or became 

embedded within welded (consolidated or compacted) 

cinders. Closer to the rim and vent, pyroclastic materials 

are commonly welded (KellerLynn 2011).

In eruptions like Capulin Volcano, magmatic gases 

provide some force to help launch lava skyward, but 

breaking of the lava into cinders tends to happen 

passively in the air (Sayre and Ort 1999). By comparison, 

in eruptions of higher silica magmas, magmatic gases 

provide explosive force and break the magma into 

pieces, forming pumice.

The cinder-cone eruption ceased when magmatic gases 

tapered off, resulting in less pressure to send the lava 

flying into the air. As the eruptive column decreased in 

height, cinders changed to spatter (larger pieces of lava, 

heavier and with less gas pressure behind them leading 

to less airtime for cooling), forming the spatter rampart 

that protects the rim and coats the inside of the cinder 

cone. 

Twenty-four spatter deposits and one spatter flow) are 

part of the GRI GIS data set (see Map Unit Properties 

Table and volcanic features map, in pocket). These 

spatter deposits, however, were mapped in the boca 

(mouth of the volcano), and not shown as part of the 

cinder cone itself. 

Volcanic Features

In addition to Capulin Volcano, Richman (2010)—the 

source map for the GRI GIS data set—included the 

following volcanic features: 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 squeezeups, and 18 tumuli (see Map Unit Properties Table and 

volcanic features map, in pocket). With the exception of 

the pooled lava flow east of the main cone, all of these 

features occur on the western side of the volcano in 

the boca, which Richman (2010) mapped in detail. In 

addition, the GRI GIS data set identifies seven vents: 

four within Capulin Volcano National Monument, two 

at Mud Hill, and one at Baby Capulin.

The following descriptions of these volcanic features/

map units were compiled using Mathis (1999), Sayre 

and Ort (1999), Dektor (2007), and Richman (2010).

Boca Rampart

Eruptions that occur on the flanks or at the base of a 

cinder cone are referred to as coming from the boca, 

meaning “mouth” in Spanish. Capulin Volcano’s boca is 

the area on the western side of the cone where volcanic 

activity was concentrated following the cone-building 

Figure 13. Photograph of a bomb. Bombs ejected 

out of a vent are 64 mm (2.5 in) or more in diameter 

and have a hollow or vesicular interior. They are 

viscous pyroclasts, shaped while in flight. This one is 

exposed in a layer of welded cinders along Volcano 

Road. Photograph by Katie KellerLynn (Colorado State 

University).

Figure 14. Photograph a block along Volcano Road. 

Blocks are ejected in a solid state. This block (arrow) 

is an estimated 2 m (6 ft) long. Photograph by Katie 

KellerLynn (Colorado State University).
14

eruption. Because activity shifted to the boca, the 

cinder cone was never breached, and its classic shape 

was preserved (KellerLynn 2011). Lava for the Second 

Series, Third Series, and Fourth Series flows emanated 

from vents in the boca (Sayre and Ort 1999).

Boca eruptions are commonly associated with cindercone eruptions. Capulin Volcano’s boca, however, is 

more complex than most. The boca rampart is a massive 

feature created by the accumulation of other features 

such as lava levees, lava lakes, and lava tubes (Richman 

2010). The surface level of the boca varied throughout 

the eruption: as some lava flows built up, others would 

drag portions of the boca away. The features in the boca 

today are the last things to have developed, or represent 

rocks that were not carried away by flowing lava. For 

example, the southern and western walls of the boca 

formed when lava flows spread out from a vent. These 

rubbly walls of rock were left behind when the lava 

flow either receded, stopped, or was redirected. The 

walls served as margins that contained lava lakes and 

through which lava cascaded. Variations in topography 

and landforms of today’s boca make it an ideal place 

to visualize complex processes that occurred as lava 

erupted (Mathis 1999).

Lava

As delineated by Richman (2010), the lava map unit 

represents solidified lava flows; that is, a lateral, surficial 

outpouring of molten rock from a vent or fissure. A 

distinctive characteristic of the lava flows associated 

with Capulin Volcano are pressure ridges—elongate, 

usually arcuate ridges formed on the congealed crust 

of a lava flow. Pressure ridges form under lateral 

compression or where blocky lava is forced to pile up. 

The ridges are generally perpendicular to the direction 

of flow and are convex downstream. Pressure ridges are 

visible on a Second Series flow lobe, south of Capulin 

Volcano (fig. 15). 

Lava Cascade

Lava cascades resemble fluvial features or “rivers 

of stone” (Mathis 1999, p. 53). They form as fluid, 

incandescent lava passes over a cliff or other precipitous 

segment along the course of a lava flow. These features 

occur where lava cascaded through the boca wall or 

between lava levees in the boca. They are shown as line 

features on the digital geologic map (Richman 2010; see 

volcanic features map, in pocket). 

Lava Lake

During an eruption, a lava lake consists of molten lava 

pooled within a depression or low area, including a 

volcano’s crater. As bubbles of gas burst through the 

surface of a lake, spatter is deposited on surrounding 

“banks” (see “Spatter Deposit” section). Additionally, 

lava lakes may show evidence of having swirled like a 

whirlpool.

The boca at Capulin Volcano contains 19 lava lakes, 

which are topographically recognizable as flat areas. 

Lava lakes also occur in the Second Series and Third 

Series lava flows (Dektor 2007). They were not all active 

at the same time.

The flatness and accessibility of one solidified lava lake 

in the boca prompted the National Park Service to use 

it as a campground (fig. 16). Although the campground 

was closed in 1969, a stone fireplace remains, standing 

as a remnant of past use (fig. 17).

Figure 15. Satellite imagery of pressure ridges and 

cinder cone. Second Series lava flows south of Capulin 

Volcano have prominent pressure ridges, which formed 

at the time of the eruption. Graphic compiled and 

annotated by Jason Kenworthy (NPS Geologic Resources 

Division). Aerial imagery from ArcGIS “World Imagery” 

basemap using data from Esri, DigitalGlobe, GeoEye, 

i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, 

IGP, swisstopo, and the GIS User Community.
15

Other than this fireplace, human-constructed features 

using local basalt are rare at Capulin Volcano National 

Monument. Cordero (2011) documented one other 

potentially historical (or possibly modern) feature at 

the monument—a rock wall composed of dry-laid, 

local, basalt cobbles. No artifacts are associated with 

the wall, so neither its age nor cultural affiliation could 

be established with any degree of certainty. The wall 

probably represents an episode of single use, but its 

function is unclear (Cordero 2011). 

Lava Levee

Named for their similarity to fluvial levees, a lava levee 

is the chilled margin along an actively flowing “stream” 

of lava. Levees increase in height as a result of periodic 

overflow, and may be left higher than the surface of a 

lava flow when flow in the lava channel decreases. They 

are broad, low embankments on the side of a lava flow.

Lava Ridge

Richman (2010) mapped 18 lava ridges in Capulin 

Volcano’s boca (see volcanic features map, in pocket). 

They are rocky features with a linear form similar to 

levee boundaries, but according to Richman (2010), 

ridges do not create a definable area of raised levees or 

spatter deposits. 

Pooled Lava Flow

Sayre and Ort (1999) identified a feature that they 

referred to as a “pooled lava flow” on the eastern 

boundary of Capulin Volcano National Monument. 

Investigation by Richman (2010) revealed a lava feature 

in this general area, which was mapped as part of the 

First Series lava flows, and as such, would have been 

emplaced at the time of the cone-building eruption. It 

is not clear, however, if this feature was what Sayre and 

Ort (1999) were referring to as a “pooled lava flow” 

(Richman 2010).

Push-Up

A push-up is a hardened surface of a lava flow that 

has been pushed up from below and tilted by molten 

lava within a lava flow. Richman (2010) mapped one 

push-up on the eastern edge of the boca, above a levee 

feature. 

Rafted Cinder Cone

Two rafted cinder cones occur in the boca. They now 

appear as hills composed of cinders resting at their 

angle of repose. They were parts of the main cinder 

Figure 16. Photograph of lava lake. A lake of pooled 

lava now appears as a flat, grassy area (oval) in the 

boca at Capulin Volcano National Monument. In the 

1930s–1960s, the flat area hosted a campground. 

Photograph from Sayre and Ort (1999, figure 14) 

available at http://geoinfo.nmt.edu/publications/

openfile/downloads/OFR500-599/526-550/541/

ofr_541.pdf (accessed 29 October 2014).

Figure 17. Photograph of stone fireplace. Perhaps 

unbeknown to its builders in 1934, the stone fireplace 

was constructed in an ancient lava lake, which provided 

a flat area for a campground. The campground closed 

in 1969, but the fireplace still stands. National Park 

Service photograph from Cordero (2011, front cover).
16

cone that were carried away by flowing lava. They 

comprise the highest elevations in the boca.

Spatter Deposit

A spatter deposit is an accumulation of fluid pyroclasts 

that coats the surface around a vent or above a crack 

in the crust of a lava flow. A spatter deposit also may 

form as gas bubbles burst through a magma body, such 

as a lava lake. Spatter may build into small mounds or 

chimneylike spires, called spatter cones or hornitos 

(Spanish for “little oven”). At Capulin Volcano, spatter 

deposits coat the entire inside of the crater (Sayre and 

Ort 1999). Richman (2010) mapped 24 spatter deposits 

throughout the boca; they are irregular low rocky hills 

and mounds. 

Spatter Flow

A spatter flow is a lava flow that originates as an 

accumulation of spatter but is hot and fluid enough to 

flow under its own weight. Richman (2010) mapped one 

spatter flow in the boca. Spatter flows also occur at the 

rim of Capulin Volcano (Sayre and Ort 1999).

Squeeze-Up and Tumulus

The GRI GIS data set includes 23 squeeze-ups (an 

accumulation of lava “squeezed up” through a crack 

in the surface of a lava flow; fig. 18) and 18 tumuli 

(doming up of a lava flow surface; fig. 19). Identification 

of a squeeze-up vs. a tumulus in the field is subjective, 

but based on the descriptions provided by Mathis 

(1999), Richman (2010) apparently mapped linearshaped features as squeeze-ups whereas bulbousshaped mounds were mapped as tumulus (see volcanic 

features map, in pocket). As such, these map units 

were categorized based on shape rather than genesis. 

Glossary of Geology (Neuendorf et al. 2005) defines 

squeeze-ups, not tumuli, as forming by extrusion of lava 

onto the surface of a flow. Tumuli result from buckling 

of the flow crust, aided by pressure of the underlying 

liquid lava. 

Vent

A vent is an opening at Earth’s surface through which 

volcanic materials explode, spatter, burst, or spill onto 

the surface. The GRI GIS data set shows seven vents: 

four are within the monument—one northeast of the 

main cone, one within the main cone, and two in the 

boca (see lava flow series map, in pocket). The two vents 

in the boca, one north and one south, are surrounded 

by spatter deposits built into ramparts. These are 

places where lava poured out and fed the lava flows 

on that side of the volcano (Michael Ort, Northern 

Arizona University, professor, email communication 

to Stephanie O’Meara, Colorado State University, 

geologist/GIS specialist/data manager, 6 November 

2014). In the GRI GIS data set, the Capulin Volcano 

vent and the two vents in the boca consist of map units 

and point features. The other four vents are point 

features.

Figure 18. Photograph of a squeeze-up. This linear 

squeeze-up is displayed prominently in the picnic area 

of Capulin Volcano National Monument. Bulbousshaped features were mapped as tumuli. Photograph 

from Sayre and Ort (1999, figure 10) available at

http://geoinfo.nmt.edu/publications/openfile/downloads/

OFR500-599/526-550/541/ofr_541.pdf (accessed 29 

October 2014).

Figure 19. Photograph of a tumulus. Richman (2010) 

mapped this feature on the Nature Trail, next to the 

visitor center, as a tumulus (bulbous-shaped mound of 

lava). Linear-shaped features were mapped as squeezeups. Photograph by Shirley Lael from Huner and Lael 

(2003, figure 1.4).
17

Volcanic activity at Capulin Volcano started along a 

fissure or series of small vents (Sayre and Ort 1999). 

The vent northeast of the cinder cone is representative 

of this early eruptive phase (First Series). Eventually, 

extrusion of lava along this fissure or series of small 

vents coalesced into a single vent around which the 

Capulin Volcano cinder cone formed. This is the vent 

marked near the center of the main cone (Richman 

2010). The vent for the cone-building eruption, located 

at the bottom of the crater, is now plugged and covered 

by blocks eroded from the crater (fig. 20; Mathis 1999).

After the cone-building eruption ceased, activity shifted 

to the boca, where lava oozed out of the side of the 

cinder cone and traveled south down a narrow valley 

through what is now the picnic area. Next, the southern 

vent in the boca began erupting, sending lava south with 

a westward component (Third Series). Finally, Fourth 

Series lava erupted from the northern vent in the boca, 

flowing north then between the main cone and Mud 

Hill (see lava flow series map, in pocket). 

Age of Capulin Volcano

Capulin Volcano erupted 55,000 ± 2,000 years ago 

(Zimmerer et al. 2014; Zimmerer 2015). This age 

is a major revision from the originally published 

interpretation by Muehlberger (1955), which stated that 

Capulin Volcano erupted between 8000 BC and 2400 

BC. 

The idea that Capulin Volcano erupted less than 10,000 

years ago was a part of scientific literature for many 

years. Notably, the original age estimate was not the 

result of analysis performed on Capulin Volcano rocks. 

As discussed below, Sayre et al. (1995) were the first 

to analyze rocks from Capulin Volcano to determine 

the volcano’s age. The “less than 10,000-year-old age” 

was obtained through correlation with deposits at the 

well-known Folsom Site, which is 16 km (10 mi) from 

Capulin Volcano. Discovered in 1908 and excavated 

in 1926, the Folsom Site became a national historic 

landmark in 1961 (National Park Service 2014a). The 

site contains bones of an extinct bison (Bison antiquus 

taylori) and spear points in an alluvial deposit. The 

site is significant because of the direct association of 

projectile points with bison fossils, which pushed back 

the accepted timing that humans first arrived in the 

region (Cook 1927; Figgins 1927). 

Bryan (1937) was the first to study the geology of the 

Folsom Site, and he identified two alluvial sequences, 

the lower of which is the Folsom occupation horizon. 

The lower alluvium has an age of 8000 BC; the upper 

alluvium has an age of 2400 BC (Muehlberger 1955). 

In the Dry Cimarron River valley, 14 km (9 mi) 

downstream from the Folsom Site, Muehlberger (1955) 

identified Capulin Basalt sandwiched between what 

he interpreted as Bryan’s two alluvial deposits, thus 

deriving his original age estimate. Subsequent work 

by Anderson and Haynes (1979), however, identified 

several distinct alluvial deposits at the Folsom site (in 

addition to Byran’s two), and concluded that the basalt 

flow in the Dry Cimarron valley overlies an alluvial 

sequence older than the Folsom occupation horizon 

(of 8000 BC). A baked organic soil from this horizon 

yielded an age of 22,360 ± 1,160 radiocarbon years 

before present (BP), or 25,091–27,442 calendar years 

Figure 20. Photograph of the Capulin Volcano vent. 

During the cone-building eruption, cinders and other 

pyroclasts were blasted upward from the vent of 

Capulin Volcano. Today, the vent is covered by volcanic 

rocks eroded from the crater walls. Photograph by Katie 

KellerLynn (Colorado State University).
18

ago or 25,776–23,540 BC (as calibrated using Stuiver 

et al. 2015). Thus the age of Capulin Volcano “became 

older” than originally interpreted. Furthermore, the 

age by Anderson and Haynes (1979) was a minimum 

age; the actual age could have been older due to 

contamination of the sample by modern plant material.

In 1995, W. O. Sayre and others analyzed rocks from 

Capulin Volcano to determine the volcano’s age. They 

applied the cosmogenic helium technique, which is 

a useful method for dating young volcanic lava flows 

and provides information on how long a rock sample 

has been within 1 m (3 ft) of Earth’s surface. These 

investigators selected a sample from the boca that 

yielded an age of 59,000 ± 6,000 (calendar) years old. 

In another study, Stroud (1997) used the argon-argon 

(Ar-Ar) technique to date four samples from various 

locations on the volcano that yielded a weighted average 

of 56,000 ± 8,000 years ago. These two studies—Sayre 

et al. (1995; cosmogenic helium) and Stroud (1997; 

Ar-Ar)—produced comparable dates, which also are 

consistent with the apparent state of erosion of cones 

of similar age throughout the Southwest (Aubele and 

Crumpler 2001). 

Analytical improvements to the argon-40/argon-39 

(40Ar/39Ar) dating technique provided another 

opportunity to date young volcanic rocks, to an 

unprecedented level of precision (Zimmerer et al. 

2014). This recent study dated flows and cones in and 

surrounding Capulin Volcano National Monument, 

yielding a highly precise age of 55,000 ± 2,000 years ago 

for the eruption of Capulin Volcano (Zimmerer 2015).

View from Capulin Volcano

In the late 1930s and early 1940s, Homer Farr, 

the custodian of Capulin Mountain National 

Monument from 1923 to 1955, wrote many letters 

to the superintendent of the Southwestern National 

Figure 21. Panoramic views from Capulin Volcano. The summit of Capulin Volcano offers a 360° panoramic view. Both 

views shown here are from the Crater Rim Trail. Looking west-southwest (upper photograph), visitors can see some 

of the older volcanoes that are part of the Raton-Clayton volcanic field. The prominent rounded hill just beyond 

the town of Capulin is the 240,000 ± 7,000-year-old Horseshoe Crater. Note the playas in the middle ground of the 

photograph. Looking northeast (lower photograph), visitors can see Baby Capulin, which erupted 46,000 ± 4,000 years 

ago. The prominent quarry near the center of the photograph is the Twin Mountain volcano, which erupted 40,000 

± 4,000 year ago. The foreground contains the Capulin and Mud Hill lava flows. Photographs by Matthew Zimmerer 

(MattZPhotography, www.mattzphotography.com [accessed 11 September 2015], used with permission), processed 

using Adobe Lightroom and stitched together using Hugin.
19

Figure 22. Satellite imagery with landmarks around Capulin Volcano. From the summit of Capulin Volcano (orange 

circle), visitors can see for miles on a clear day. White circles represent 5-mile increments from Capulin Volcano. 

Geographic points of interest include the following: 1. West Spanish Peak, 4,148 m (13,610 ft). 2. Greenhorn Mountain, 

3,764 m (12,349 ft). 3. Towndrow Peak, 2,624 m (8,609 ft). 4. Red Mountain, 2,574 m (8,445 ft). 5. Culebra Range of 

the Sangre de Cristos, distance of 119 km (72 mi). 6. Jose Butte, 2,234 m (7,330 ft). 7. Mud Hill, 2,195 m (7,200 ft). 8. 

Baby Capulin, 2,102 m (6,900 ft). 9. Twin Mountain, 2,073 m (6,800 ft). 10. Gaylord (Carr) Mountain, 2,103 m (6,900 

ft). 11. Robinson Peak, 2,495 m (8,185 ft). 12. Green Mountain, 2,410 m (7,900 ft). 13. Larga Mesa, 2,316 m (7,600 

ft). 14. Horseshoe Mountain, 2,380 m (7,810 ft). 15. Sierra Grande, 2,655 m (8,711 ft).16. Rabbit Ear Mountain, 1,811 

m (5,940 ft) and a distance of 27 km (44 mi). 17. Tinaja Peak, 2,380 m (7,810 ft). 18. Laughlin Peak, 2,688 m (8,820 

ft). 19. Raspberry Mountain, 2,484 m (8,150 ft). 20 and 21. Pine Buttes, 2,560 m ( 8,400 ft) and 2,560 m (8,400 ft). 22. 

Palo Blanco, 2,556 m (8,385 ft). 23. Malpie Mountain, 2,268 m (7,440 ft). Graphic by Jason Kenworthy (NPS Geologic 

Resources Division), with annotations from Huner and Lael (2003, figure 5.1). Landsat imagery extracted from Google 

Earth.
20

Monuments that repeatedly pointed out what Farr 

considered the monument’s two most important 

resources: (1) the volcano, and (2) the view from the top 

of the volcano (Huner and Lael 2003). The spectacular 

view is most likely what led Farr to build a road to the 

summit (Huner and Lael 2003). 

Today, the Crater Rim Trail circumnavigates the 

volcano and provides a 360° view (fig. 21). In the past, 

monument staff claimed you could see five states 

from the crater rim, but without notable landmarks, 

identifying Kansas is impossible. Thus, touting a 

viewshed (area visible to the human eye from a fixed 

vantage point) of four states (New Mexico, Colorado, 

Oklahoma, and Texas) is the present custom and what 

is listed on current interpretive panels (Lynn Cartmell, 

Capulin Volcano National Monument, lead park ranger, 

written communication, 17 February 2015). 

The “dramatic view” is one of four statements of 

significance identified in the monument’s 2010 general 

management plan. The other three statement of 

significance are the classic cinder cone, occurrence in 

the geologically diverse Raton-Clayton volcanic field, 

and the cinder cone’s accessibility (National Park 

Service 2010). The view is also one of the monument’s 

fundamental resources and values identified in the 

foundation document (National Park Service 2014c). 

Taking into consideration factors such as artificial vs. 

natural features in the viewshed, the natural resource 

condition assessment (Bennetts et al. 2012) determined 

the current condition (quality) of the viewshed to be in 

good condition. 

During the GRI scoping meeting in 2011, monument 

staff indicated that visitors are as interested, or perhaps 

more interested, in the surrounding viewshed and 

outlying volcanic landscape as they are in the volcano 

itself. The view seems to be the reason for return visits 

(KellerLynn 2011). 

Because Capulin Volcano is centrally located in 

the Raton-Clayton volcanic field, its rim is an ideal 

place to get an overview of the important features 

of the volcanic field (figs. 8 and 22). The most recent 

volcanism (Capulin phase) took place in the immediate 

vicinity of Capulin Volcano, so the crater rim is a good 

place to see “fresh” volcanic features (Stormer 1987). 

Nearby topographic humps mark the locations of vents. 

Prominent pressures ridges and squeeze-ups rise above 

the otherwise level surfaces of lava flows. Volcanic 

landmarks in the vicinity include Baby Capulin, Mud 

Hill, and Sierra Grande (fig. 22). 

Baby Capulin

Baby Capulin is one of the youngest volcanoes in the 

region (Muehlberger et al. 2010). Based on new dating 

by Zimmerer et al. (2014), it is now known to be the 

third youngest: Purvine Hills and Twin Mountain 

erupted 32,000 ± 5,000 and 40,000 ± 4,000 years ago, 

respectively; Baby Capulin erupted 46,000 ± 6,000 years 

ago. 

Figure 23. Panoramic view of Baby Capulin. This panoramic view is looking east from Highway 325 toward Baby 

Capulin (on the left). Emery Peak is behind Baby Capulin. Photograph by Matthew Zimmerer (MattZPhotography, 

www.mattzphotography.com [accessed 11 September 2015], used with permission), processed using Adobe Lightroom 

and stitched together using Hugin.
21

The Baby Capulin cinder cone formed early in the 

volcanic eruption, along with a number of spatter cones 

that surround the cone to the south and east. These 

spatter cones fed the lava flows that traveled northward 

to Folsom and into the Dry Cimarron River valley 

(Sayre and Ort 1999). Thus like Capulin Volcano, Baby 

Capulin is a cinder cone that formed during a conebuilding eruption. In contrast, however, the eruption of 

Baby Capulin produced more lava flows than pyroclasts 

(cinders). 

Baby Capulin is outside Capulin Volcano National 

Monument but within its viewshed, approximately 3 

km (2 mi) to the northeast (fig. 23). Baby Capulin’s bare 

cone and crater are readily visible from Crater Rim 

Trail. Baby Capulin lavas are similar in petrographic 

appearance to Capulin Volcano lavas, except that they 

contain fewer xenocrysts.

Mud Hill

The big volcano about 0.6 km (1 mi) north of Capulin 

Volcano is Mud Hill. Its rim is covered with trees. Like 

Capulin Volcano, Mud Hill erupted during the Capulin 

phase but is significantly older (1.69 million ± 30,000 

years ago; Zimmerer 2015). 

Mud Hill formed by a very different process than 

Capulin Volcano. It was the result of a phreatomagmatic 

(“phreato” meaning reservoir or well in Greek; also 

called hydrovolcanic) eruption, where the interaction 

of magma and water (shallow groundwater or surface 

water) drives the explosion. As such, the Mud Hill 

eruption was considerably more violent than Capulin 

Volcano because heating of water flashed to steam, 

blasting magma and breaking it into fragments 

(pyroclasts). 

Various descriptions of Mud Hill refer to it as a 

“maar volcano,” “tuff ring,” or both. Some geologists 

distinguish the two: a maar is a pyroclastic cone in 

which the crater lies below the surrounding ground 

level, whereas a tuff cone is a pyroclastic cone with the 

crater above the surrounding ground surface (Mathis 

1999). 

When most of the water had been used up in the 

explosion of Mud Hill, lava began to pour out of the 

vent. Eventually, a lave flow breached the southern side 

of Mud Hill, leaving a horseshoe-shaped edifice. Lava 

from Capulin Volcano subsequently altered the area to 

the south of Mud Hill (Sayre and Ort 1999).

Sierra Grande

Standing 2,655 m (8,711 ft) above sea level, Sierra 

Grande is the largest volcano in the Raton-Clayton 

volcanic field (fig. 24). It is composed of 23 km3 (6 mi3) 

of thick, viscous lava flows and very little pyroclastic 

material (Wood and Kienle 1990; Sayre and Ort 1999; 

Aubele and Crumpler 2001). Sierra Grande is a notable 

exception to the basaltic cinder cones that characterize 

the Raton-Clayton volcanic field (fig. 8). Although the 

Sierra Grande eruption initially produced voluminous 

basalt flows, it ultimately constructed an edifice 

composed of andesite.

Figure 24. Photograph of Sierra Grande. The largest 

volcano in the Raton-Clayton volcanic field is Sierra 

Grande, which rises about 600 m (2,000 ft) above 

the surrounding plain and is about 15 km (9 mi) in 

diameter. The volcano is an important component of 

Capulin Volcano National Monument’s viewshed, and 

is visible in the distance to the southeast of Capulin 

Volcano (see fig. 22). Photograph by Matthew Zimmerer 

(MattZPhotography, www.mattzphotography.com

[accessed 11 September 2015], used with permission), 

processed using Adobe Lightroom.
22

Aubele and Crumpler (2001, p. 72) described Sierra 

Grande as an “andesite shield volcano [italics added]” 

whereas Sayre and Ort (1999, p. 59) described it as a 

“stratovolcano [italics added] predominantly composed 

of andesite lavas.” In short, Sierra Grande poses a 

challenge to classic classification schemes (fig. 7). 

Based on its low profile and a slope of approximately 

8°, Sierra Grande fits into the “shield volcano” category. 

However, shield volcanoes are characteristically 

composed almost entirely of fluid, basaltic lava flows 

that spread away from vents for tens of kilometers, but 

Sierra Grande consists almost entirely of andesitic lava 

flows (60%–62% silica) that spread less than 8 km (5 

mi) from the vent, making the volcano only 15 km (9 mi) 

across. Therefore, based on rock type and volcano size, 

Sierra Grande fits into the “stratovolcano” category. 

Additionally, an essential feature of a stratovolcano is a 

conduit system through which magma from a reservoir 

deep in Earth’s crust rises to the surface (Watson 2011). 

Sayre and Ort (1999) interpreted such a system for 

Sierra Grande.

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 monument’s viewshed (fig. 22). Baldwin and 

Muehlberger (1959) highlighted these lakes and 

concluded that most of them probably formed as a 

result of wind erosion that scoured depressions into 

bedrock (e.g., Dakota Sandstone) which became filled 

with water. Some playa lakes represent areas where the 

crust of a lava flow collapsed. The town of Clayton, 

southeast of Capulin Volcano National Monument, has 

examples of this type (Baldwin and Muehlberger 1959). 

Aeolian Features

Sand dunes, sand sheets, and deposits of loess 

(windblown silt) are aeolian features created by 

wind erosion, transportation, and deposition of 

sediments (Lancaster 2009). In volcanic landscapes, 

ash (fine-grained material ejected from a volcano and 

transported by the wind) may be a significant aeolian 

feature. Compared to caldera-forming eruptions such 

as Mount Mazama (see GRI report about Crater Lake 

National Park by KellerLynn 2013) and Valles caldera 

(see GRI report about Bandelier National Monument 

by KellerLynn 2015), however, cinder cones produce 

very little ash. Unlike ash layers from the Yellowstone 

caldera, which completely covered New Mexico and 

surrounding states (see Izett and Wilcox 1982), ash 

from Capulin Volcano spread only an estimated 1 km 

(0.6 mi) away from the vent (Bill McIntosh and Nelia 

Dunbar, New Mexico Bureau of Geology and Mineral 

Resources, volcanologist and geologist, personal 

communication during GRI scoping meeting, 10 May 

2011). 

A notable aeolian feature at Capulin Volcano National 

Monument is the asymmetry of the crater rim; the rim 

is higher on the northeastern side (fig. 25). At the time 

of the cone-building eruption, prevailing southwesterly 

winds caused more cinders to accumulate on the 

opposite (northeastern) side of the volcano; this 

asymmetry remains today.

Loess is another aeolian feature at Capulin Volcano 

National Monument. Loess-infilling of vesicles and 

cracks on lava flow surfaces serves as an informal dating 

method. Based on the amount of loess infilling and 

cover, geologists can estimate the relative age of lava 

flows and associated landscapes. This field method is a 

form of relative dating used in the absence of isotopic 

ages. A clean, loess-free surface indicates a “young” 

flow. A surface where vesicles and cracks are filled with 

loess indicates a moderate age. Removal of topographic 

highs by loess indicates old age (KellerLynn 2011).

In addition, loess plays a role in soil formation. 

Weindorf et al. (2008) and Weindorf and Zhu (2010) 

investigated spatial variability of soil properties at 

Capulin Volcano National Monument. Bauman (1999) 

studied loess on the Carrizozo lava flow in south-central 

New Mexico (fig. 4) and analyzed the influences of 

climate, provenance (source of sediment), and surface 

cover types on soil formation. Bauman (1999) found 

that soils on the Carrizozo flow are aeolian in origin and 

not the outcome of basaltic weathering. These findings 

and methods may be applicable to the lava flows 

associated with Capulin Volcano. 

K-T Boundary

A massive worldwide extinction marks the CretaceousTertiary (“K-T”) boundary 66.0 million years ago (fig. 

3). An estimated 50% of all species, including terrestrial 

dinosaurs, did not survive this extinction event. An 

accepted scientific view is that these extinctions 

coincided with a cataclysmic collision of an asteroid 

or comet with Earth. The presence of extraterrestrial 
23

material (iridium) associated with this collision has 

been identified in Cretaceous-Tertiary deposits around 

the globe. A few such deposits occur in New Mexico, 

notably in rocks along Interstate 25 through Raton Pass 

(fig. 26), and in an outcrop of the Raton Formation 

atop Goat Hill (fig. 27), just outside Raton. The actual, 

physical boundary is a thin layer of iridium-rich clay. 

At the exposure near Goat Hill, a sign “iridium layer” 

indicates the boundary’s location (fig. 27).

The K-T boundary often captures the public’s 

imagination because it resulted in a world without 

dinosaurs. Although Capulin Volcano National 

Monument does not contain the K-T boundary, the 

exposure at Goat Hill is publicly accessible, and its 

proximity to the monument may be of interest to 

visitors.

Paleontological Resources

No fossils have been discovered at Capulin Volcano 

National Monument, to date. While this report was 

in review, an updated summary of paleontological 

resources from the NPS Southern Plains Network, of 

which the monument is a part, was completed (Tweet 

et al. 2015). That report replaces the earlier report by 

Koch and Santucci (2003). In general, fossils are rare 

in igneous deposits, except for tree molds, which form 

when fluid lava engulfs a tree, which is later incinerated 

or decays away, leaving a cylindrical hollow. In some 

instances, tree molds preserve an impression of a 

tree’s original bark. Tree molds also may be horizontal 

impression on the surface of a lava flow where a tree fell 

over and was later incinerated or decayed away. Within 

the National Park System (see Santucci et al. 2012), 

this particular kind of fossil has been documented at 

Figure 25. Photograph of Capulin Volcano. Capulin Volcano is a classic example of a cinder cone. The crater 

is approximately 130 m (420 ft) deep and 440 m (1,450 ft) across. The base of the mountain is 6 km (4 mi) in 

circumference. Volcano Road spirals up the volcano, providing access to panoramic views of the surrounding RatonClayton volcanic field. Note the asymmetry of the cone, which is higher on the northeastern side as a result of aeolian 

processes during the cone-building eruption. National Park Service photograph available at http://www.nps.gov/

storage/images/cavo/Webpages/gallery-01.html (accessed 20 January 2015).
24

Craters of the Moon National Monument in Idaho, 

El Malpais National Monument in New Mexico (see 

GRI report by KellerLynn 2012a), Lava Beds National 

Monument in California (see GRI report by KellerLynn 

2014c), and Hawaii Volcanoes National Park and 

Puuhonua o Honaunau National Historical Park in 

Hawaii (see GRI reports by Thornberry-Ehrlich 2009, 

2011). No tree molds have been documented at Capulin 

Volcano National Monument to date (Justin Tweet, 

NPS Geologic Resources Division, guest scientist, email 

communication, 21 May 2015). 

Pack rat (Neotoma spp.) middens are another potential 

source of paleontological information, though none 

have presently been documented in the monument 

to date. Pack rat middens are an important tool for 

reconstructing the paleoecology and climate of late 

Pleistocene and Holocene environments in western 

North America. Thirty-three National Park System 

units are known to contain pack rat middens (Tweet et 

al. 2012). Pack rat middens are primarily examined for 

plant macrofossils, but also pollen (Anderson and Van 

Devender 1995), insects (Elias et al. 1992), vertebrates 

(Mead and Phillips 1981), stomatal density/carbon 

isotopes in leaves (Van de Water et al. 1994), and fecal 

pellets (Smith et al. 1995; Smith and Betancourt 1998). 

Also, the dung of extinct mammals contained in pack 

rat middens may yield paleobotanical information 

(Davis et al. 1984; Mead et al. 1986; Mead and 

Agenbroad 1992; Hunt et al. 2012).

Larger cavities in basalt lava flows are potential locales 

for pack rat middens at Capulin Volcano National 

Monument. Climate is the main consideration; 

the monument is right on the eastern fringe of 

where ancient middens typically are found (Justin 

Tweet, NPS Geologic Resources Division, guest 

scientist, email communication, 21 May 2015). 

Preliminary paleontological resource management 

recommendations are presented by Tweet et al. (2015).

Figure 26. Photograph of the K-T boundary at Raton 

Pass. The famous Cretaceous-Tertiary (K-T) boundary is 

exposed in a few places in northeastern New Mexico, 

for example, along Interstate 25 at Raton Pass. The 

author (Katie “K-T” KellerLynn) points out the iridiumrich layer in the Raton Formation. Photograph by Lisa 

Norby (NPS Geologic Resources Division).

Figure 27. Photographs of the K-T boundary at 

Goat Hill. The iridium-rich clay layer that marks the 

worldwide extinction of dinosaurs is exposed near 

Capulin Volcano National Monument, on Goat Hill, 

just outside the city of Raton. Photographs by Katie 

KellerLynn (Colorado State University).
25

Geologic Resource Management Issues

This chapter describes geologic features, processes, or human activities that may require management 

for visitor safety, protection of infrastructure, and preservation of natural and cultural resources in 

Capulin Volcano National Monument. The NPS Geologic Resources Division provides technical and 

policy assistance for these issues.

During the 2011 scoping meeting (see scoping summary 

by KellerLynn 2011), participants (see Appendix A) 

identified the following geologic resource management 

issues:

● Volcano Road

● Erosion

● Slope Movements

● Aeolian Processes

● Wind Energy Development

● Cave Management

● Cinder Mining

● Volcano Hazards and Risk

● Geothermal Systems and Hydrothermal Features

Resource managers may find Geological Monitoring 

(Young and Norby 2009) useful for addressing 

these resource management issues. Geological 

Monitoring provides guidance for monitoring 

vital signs—measurable parameters of the overall 

condition of natural resources. Each chapter covers 

a different geologic resource and includes detailed 

recommendations for resource managers and suggested 

monitoring methods. An online version of the manual is 

available at http://go.nps.gov/geomonitoring (accessed 

29 May 2015).

A foundation document (National Park Service 2014c) 

and natural resource condition assessment (Bennetts 

et al. 2012) also provide information about the geologic 

resources of the monument. The foundation document 

lists the following as fundamental resources or values: 

volcanic features and geologic processes, scenic/historic 

viewshed, and opportunities for scientific study. Other 

important resources in the monument as identified in 

the foundation document are cultural resources and 

rare species. Volcano Road and the Crater Rim Trail 

are part of a historic designated cultural landscape. 

The framework of the natural resource condition 

assessment includes the following components under 

“Geology”: presence/absence of accelerated erosion 

and severity of erosion. Geologic features and processes 

and some of the resource management issues described 

in this chapter affect those values and resources.

In the following sections of this report, three 

investigations are proposed that could be conducted 

by a Geoscientists-In-the-Parks (GIP) participant: 

(1) triggers of slope movements (see “Slope 

Movements” section, (2) a cave inventory (see 

“Cave Management” section), and (3) hydrothermal 

features (see “Geothermal Systems and Hydrothermal 

Features” section). The GIP website (http://go.nps.

gov/gip; accessed 27 January 2015) contains additional 

information about the GIP program. The NPS Geologic 

Resources Division administers this program.

Volcano Road

“Volcano Road” (as per Federal Highway 

Administration 2010) has been referred to as “Crater 

Ascent Road” (National Park Service 1977), “Mountain 

Road,” and “Capulin Volcano Road.” The road spirals 

up Capulin Volcano (fig. 25) and is an important part 

of Capulin Volcano National Monument’s cultural 

landscape (National Park Service 2014). The road 

is eligible for inclusion in the National Register of 

Historic Places, thus establishing its significance in 

accordance with 36 Code of Federal Regulations 

(CFR) Part 800—Protection of Historic Properties 

(Bennetts et al. 2012). The road also has scientific and 

educational significance. Several pullouts provide access 

to sites of geologic interest, for example, exposures of 

inclined layers of cinders (fig. 12). The road’s primary 

significance, however, is furnishing an incredible 360° 

panoramic view at the crater rim (see “View from 

Capulin Volcano” section). 

Although Volcano Road is significant for the public 

enjoyment opportunities it provides, it also has the 

greatest impact on the monument’s geologic resources, 

specifically the cinder cone (Bennetts et al. 2012). The 

road was built into the side of the volcano, undercutting 

slopes and impacting natural drainages. Along some 

road segments, the stability and integrity of the road 
26

bench itself is at risk of failure (National Park Service 

2012). Furthermore, the road’s impervious surface 

concentrates runoff, causing accelerated, and in some 

places, severe erosion. Many of the culverts associated 

with the road are inadequate for conveying intense 

storm-related runoff (fig. 28; Greco 2001). 

Based on the high proportion of culverts exhibiting 

accelerated erosion (66%) and the severity of that 

erosion (fig. 29), the natural resource condition 

assessment by Bennetts et al. (2012) considered the 

condition of “geology” (specifically the cinder cone) 

in the monument to be a “significant concern” with a 

“declining trend.” Although the monument contains 

many geologic features (see “Geologic Features and 

Processes” chapter), Bennetts et al. (2012) focused 

on the cinder cone because it is the most prominent 

feature in the monument and comprises more than 

half (56%) of the monument’s acreage. Erosion is 

expected to continue until solutions are determined and 

implemented. A $2 million effort to remediate hill slope 

erosion caused by Volcano Road was completed by the 

Federal Highway Administration in 2012. The project 

incorporated erosion control measures and repaired 

road shoulders, drainage structures, and eroded hill 

slope areas (National Park Service 2014c).

The geologic resources foundation summary (National 

Park Service 2012) identified five major aspects that 

contribute to the road’s drainage/erosion problem: 

● the ability of drainage inlets and culverts to handle 

storm events,

● the number of culverts needed to mimic natural 

hydrology,

● the alignment of drainage inlets and outlets to 

topography,

● the attenuation of discharge velocities (energy 

dissipation), and

● the reduction of accelerated erosional processes 

and the correction of altered sediment transport 

processes upslope and downslope of the road. 

Figure 28. Photograph of storm-related damage along Volcano Road. Erosion on Capulin Volcano is primarily 

associated with Volcano Road. Culverts provide narrow paths for storm-water runoff, creating erosion channels and 

gullies down the sides of the mountain. National Park Service photograph (date unknown).
27

Mitigation is essential for the long-term sustainability 

of Volcano Road and the reduction of visual impacts 

(National Park Service 2012). The geologic resources 

foundation summary (National Park Service 2012) 

recommended the completion of a long-term surface 

drainage/erosion mitigation plan. The NPS Geologic 

Resources Division could assist monument managers 

with preparing a monitoring and mitigation plan for 

Volcano Road. Photogrammetry could provide a means 

for quantitative measurement of erosion rates. The NPS 

Geologic Resources Division photogrammetry website 

(http://go.nps.gov/grd_photogrammetry; accessed 27 

January 2015) supplies additional information.

Erosion

Erosion is arguably the most significant threat 

to the geologic resources at Capulin Volcano 

National Monument (Bennetts et al. 2012). Human 

developments, primarily Volcano Road, cause the most 

obvious and severe erosion (fig. 30), but steep slopes—

generally between 40% and 60% approaching the 

crater—and highly erodible soils exacerbate the issue 

(Weindorf et al. 2008). Addressing this threat requires 

an understanding of erosional processes operating at 

the monument and the degree and severity of natural 

vs. unnatural erosion, which presently constitutes an 

information gap (Bennetts et al. 2012).

During the GRI scoping meeting/site visit on 10 May 

2011, Nelia Dunbar and Bill McIntosh (New Mexico 

Figure 29. Satellite imagery with locations of culverts along Volcano Road. Accelerated erosion that creates gullies is 

associated with culverts along Volcano Road. Yellow lines delineate the length of an eroded area. Culvert numbers are 

shown for reference. Nineteen culverts (7–9, 11–15, and 29) are experiencing accelerated erosion. Lengths of eroded 

gullies range from 10 m (34 ft) to 419 m (1,373 ft), averaging 197 m (647 ft). Culverts with the longest erosion gullies 

are 9 (419 m [1,373 ft]), 11 (372 m [1,219 ft]), and 14 (345 m [1,130 ft]). Several of the gullies extend half way or more 

down the slope of the cinder cone. Graphic from Bennetts et al. (2012, figure 4.5.4-1).
28

Bureau of Geology and Mineral Resources, geologist 

and volcanologist) pointed out the natural tendency 

for cinders to erode into gullies. This type of erosion 

has been operating since the cinder cone formed 

55,000 years ago. Various investigators have studied the 

progression of erosion on cinder cones. For example, a 

study by Renault (1989) of the Cima volcanic field in the 

eastern Mojave Desert would be applicable to Capulin 

Volcano. This study investigated four basaltic cinder 

cones of the Cima field in an attempt to understand 

the geomorphic and volcanic processes involved in 

the constructional and degradational evolution of late 

Quaternary cinder cones in arid climates. Additionally, 

several other papers—Fornaciai et al. (2010), Bemis et 

al. (2011), Doniz et al. (2011), and Inbar et al. (2011)—

provide information about the morphological evolution 

of cinder cones through time (Nelia Dunbar, New 

Mexico Bureau of Geology and Mineral Resources, 

geologist, written communication, 4 August 2011). 

Existing information related to soil erosion at Capulin 

Volcano National Monument includes a NPS Soil 

Resources Inventory (SRI), which can be found on the 

NPS Integrated Resource Management Applications 

(IRMA) at https://irma.nps.gov/App/Reference/

Profile/1048838 (accessed 27 January 2015). Also, 

Biggam (2010) performed a rapid soil assessment and 

trip report.

Erosion-related issues occur in other areas of the 

monument, though they are less severe than those along 

Volcano Road. Erosion is affecting sections of both the 

Lava Flow Trail and the fire road in the southern part 

of the monument (Bennetts et al. 2012). Cinder-mining 

activities adjacent to the monument’s northeastern 

boundary have eroded a Fourth Series lava flow (see 

“Abandoned Mineral Lands” section). Because the 

Crater Rim Trail has an impervious surface, it may pose 

some risk to the integrity of the cinder cone as a result 

of concentration of storm-water runoff. Work along the 

Crater Rim Trail during summer 2010 restored some 

eroded areas, attempting to mitigate future erosion 

(Bennetts et al. 2012).

In parts of the monument, specifically on the cinder 

cone, removal of the pinyon-juniper overstory via 

mechanical thinning left the soil surface exposed, and 

the highly erodible soils show the dramatic impacts 

of sheet, rill, and channelized erosion. The resulting 

sediment discharge has plugged drainage culverts, 

causing excessive sediment accumulation on Volcano 

Road that requires removal (National Park Service 

2012). The NPS Geologic Resources Division could 

assist with preparing erosion control procedures.

Slope Movements

Slope movements are ongoing on Capulin Volcano and 

cause cinders to slide (fig. 31), debris flows to form (fig. 

32), and entire sections of slopes to fail (fig. 33). These 

gravity-driven processes are a particular concern at 

the monument where they impact infrastructure. The 

primary concern is Volcano Road, where sliding cinders 

Figure 30. Photograph of erosion along Volcano 

Road. In spring 1967 Volcano Road was closed while 

monument personnel assessed damages and made 

repairs. In 2012, a Federal Highways Administration 

project remediated some areas of severe erosion along 

the road. National Park Service photograph from 

Bennetts et al. (2012, figure 4.5.1-7).

Figure 31. Photograph of a cinder slide on Volcano 

Road. Slope movements are ongoing at Capulin Volcano 

National Monument; the slide shown here took place 

in 2004. Cinder slides are a particular concern along 

Volcano Road. Keeping the road clear of cinders is a 

continuous maintenance activity. National Park Service 

photograph available at http://www.nps.gov/cavo/

naturescience/environmentalfactors.htm (accessed 19 

November 2014).
29

have covered sections of the road with deposits up 

to 1.5 m (5 ft) thick and as much as 60 m (200 ft) long 

(KellerLynn 2011). 

Small-scale slope movements, such as cinders sliding 

onto the road, are continuous, but large-scale events 

seem to be associated with storms and higher than 

average annual precipitation (KellerLynn 2011). In 

2010—a “wet year,” a debris flow moved across Volcano 

Road, inhibiting access and trapping vehicles at the 

summit. Precipitation in 2010 was 76 cm (30 in). By 

comparison, the annual average is 38 cm (15 in). 

A data need at the monument is a better understanding 

of the timing and triggers of large-scale slope 

movements. Such events have not been well 

documented (KellerLynn 2011). Using long-term 

weather data and historical photographs retained in the 

monument’s archives, a GIP participant would likely be 

able to make correlations and provide documentation of 

links between storms and large-scale slope movements. 

Bennetts et al. (2012) used the presence/absence 

of accelerated erosion and the severity of erosion 

as indicators/measures of the condition of geology 

at Capulin Volcano National Monument. In the 

Geological Monitoring chapter about slope movements, 

Wieczorek and Snyder (2009) described five vital signs 

for understanding and monitoring slope movements: 

(1) types of landslide, (2) landslide causes and triggers, 

(3) geologic materials in landslides, (4) measurement 

of landslide movement, and (5) assessment of landslide 

hazards and risks. Other sources of guidance for 

monitoring include The Landslide Handbook—A 

Guide to Understanding Landslides (Highland and 

Bobrowsky 2008), the USGS landslides website 

(http://landslides.usgs.gov/; accessed 27 January 2015), 

and the NPS Geologic Resources Division geohazards 

and slope-movement monitoring websites 

(http://go.nps.gov/geohazards and http://go.nps.gov/

monitor_slopes; accessed 27 January 2015). 

Aeolian Processes

Wind is a primary geologic agent at Capulin Volcano 

National Monument (Pete Biggam, NPS Geologic 

Resources Division, Soils Program lead, personal 

communication to Rob Bennetts, Southern Plains 

Network, network coordinator, November 2010). 

Capulin Volcano itself was shaped by the wind (see 

“Aeolian Features” section). Windblown transport 

of cinders onto Volcano Road is a concern for 

maintenance and safety, and dust storms can take place, 

primarily during March and April.

Grazing is commonly a factor in the amount of dust 

available for aeolian transport, but grazing within the 

boundaries of the monument ended in the late 1970s. 

Present-day construction activities, however, denude 

vegetation, making sediment available for aeolian 

transport and dust storms (KellerLynn 2011).

Figure 32. Photograph of a debris flow on Volcano 

Road. Slope movements are a common type of geologic 

hazard—a natural or human-caused condition that may 

impact park resources, infrastructure, or visitor safety. 

Debris flows have impacted Volcano Road, causing 

road closures and trapping vehicles above an affected 

road section. National Park Service photograph (date 

unknown).

Figure 33. Photograph of slope movements along 

Volcano Road. Slope movements include fall, topple, 

slide, spread, and flow of material under the influence 

of gravity. Rockfall, slope failure, and small debris flows 

are common along Volcano Road. Slope-movement 

events occur on time scales ranging from seconds to 

years, and may be triggered by storms and higher-thanaverage precipitation. National Park Service photograph 

(date unknown).
30

In the Geological Monitoring chapter about aeolian 

features and processes, Lancaster (2009) described 

the following methods and vital signs for monitoring 

aeolian resources: (1) frequency and magnitude of 

dust storms, (2) rate of dust deposition, (3) rate of sand 

transport, (4) wind erosion rate, (5) changes in total 

area occupied by sand dunes, (6) areas of stabilized and 

active dunes, (7) dune morphology and morphometry, 

(8) dune field sediment state (supply, availability, and 

mobility), (9) rates of dune migration, and (10) erosion 

and deposition patterns on dunes. Some but not all of 

these vital signs would be applicable to Capulin Volcano 

National Monument. 

Wind Energy Development

Although aeolian processes are notable at Capulin 

Volcano National Monument, scoping participants did 

not consider large-scale development of wind energy an 

issue. Because the view from Capulin Volcano is such an 

important resource, however, the NPS Intermountain 

Region has a plan to study visitor attitudes towards 

potential wind farms within the monument’s viewshed. 

The National Park Service uses a combined technical 

and policy approach to manage and protect park 

resources and values as renewable energy resources are 

identified and developed near NPS areas. The concerns 

associated with the development of onshore wind 

energy include potential habitat loss, land conversion, 

transmission infrastructure, and artificial light. The key 

impacts of onshore wind turbines include noise, turbine 

strikes, and visual impacts (National Park Service 

2014b).

Cave Management

In volcanic landscapes composed of basalt, the most 

significant cave features are lava tubes (see GRI reports 

about El Malpais and Lava Beds national monuments by 

KellerLynn 2012a, 2014c). Lava tubes are the primary 

means for distributing lava away from an erupting vent 

in these terrains. When eruption ceases and lava stops 

flowing, a cave may remain as a cavernous segment of 

an evacuated lava tube. In many cases, however, the 

roofs of lava tubes will collapse, filling the opening with 

collapse debris.

Capulin Volcano National Monument has a few known 

cave features, as well as several collapsed lava tubes. 

The NPS geologic resources foundation summary for 

Capulin Volcano National Monument (National Park 

Service 2012) listed a survey and inventory of the caves 

as a planning and data need. No geologic study or cave 

inventory is known to have been conducted, though 

some information is available in archeological reports. 

The Federal Cave Resources Protection Act of 1988 

and its subsequent regulations issued in 1993 impose 

penalties for harming a cave or cave resources and 

exempts park managers from releasing specific 

location information for significant caves in response 

to a Freedom of Information Act (FOIA) request (see 

Appendix B of this report). These regulations also state 

that “no employee shall disclose information that could 

be used to determine the location of any significant 

cave unless the authorized officer determines that 

disclosure will further the purposes of the act and will 

not create a substantial risk to cave resources of harm, 

theft, or destruction. For the National Park Service, the 

“authorized officer” is the superintendent of a park unit.

The policy of the National Park Service, pursuant 

to the Organic Act of 1916 (16 U.S.C. 1, et seq.) and 

2006 Management Policies (section 4.8.2.2; see also 

Appendix B), is that all caves are afforded protection 

and will be managed in compliance with approved 

resource management plans. Accordingly, all caves on 

NPS lands are deemed to fall within the definition of 

“significant cave.”

The management of caves—including guidance and 

protocols for all cave activities—at Capulin Volcano 

National Monument should be discussed in some 

type of management plan (Dale L. Pate, NPS Geologic 

Resources Division, Cave & Karst Program coordinator, 

written communication, 30 January 2015). An in-depth 

cave management plan may not be necessary, however. 

The NPS Geologic Resources Division can facilitate 

the development of an appropriate plan for Capulin 

Volcano National Monument.

A good first step in identifying needs of the monument 

regarding cave resources would be submittal of a 

technical assistance request to the NPS Geologic 

Resources Division. Technical assistance would be 

provided by the cave and karst specialist and include a 

review of any reports or other documentation, a visit 

to Capulin Volcano National Monument to investigate 

known cave features and collapsed lava tubes, and 

recommendations for data and information needs 

to adequately manage these resources. This would 

include an evaluation of potential bat use and guidance 

concerning white-nose syndrome, a devastating disease 
31

to bats. Additional information about white-nose 

syndrome is available from the NPS Biologic Resources 

Division website at http://go.nps.gov/wns (accessed 11 

September 2015).

Based on guidance and recommendations by a 

technical assistance request, potential sources for 

help in conducting a field survey and inventory at the 

monument may include a GIP participant. The GIP 

candidate (or anyone else) selected for this position 

should have thorough knowledge and adequate 

experience in the survey and inventories of caves, 

including how to move through and work in caves with 

minimal impacts to sensitive cave resources (Dale L. 

Pate, NPS Geologic Resources Division, Cave & Karst 

Program coordinator, written communication, 30 

January 2015).

Following an inventory, a monitoring plan could be 

established for physical properties, as well as impacts 

to sensitive cultural artifacts (National Park Service 

2012). In the Geological Monitoring chapter about caves 

and associated landscapes, Toomey (2009) described 

methods for inventorying and monitoring cave-related 

vital signs: (1) cave meteorology, such as microclimate 

and air composition; (2) airborne sedimentation, 

including dust and lint; (3) direct visitor impacts, 

such as breakage of cave formations, trail use in caves, 

graffiti, and artificial cave lighting; (4) permanent or 

seasonal ice; (5) cave drip and pool water, including 

drip locations, rate, volume, and water chemistry, pool 

microbiology, and temperature; (6) cave microbiology; 

(7) stability issues associated with breakdown, rockfall, 

and partings; (8) mineral growth of speleothems, such 

as stalagmites and stalactites; (9) surface expressions 

and processes that link the surface and the cave 

environment, including springs, sinkholes, and cracks; 

(10) regional groundwater levels and quantity; and (11) 

fluvial processes, including underground streams and 

rivers. Some of these vital signs may be pertinent to the 

caves at Capulin Volcano National Monument.

Cinder Mining

Cinder mining has occurred in the vicinity of Capulin 

Volcano National Monument. The most apparent 

operation is at Twin Mountain, which is 8 km (5 mi) 

to the northeast and visible from the crater rim (figs. 

21 and 22). The original shape of Twin Mountain was 

two parallel ridges of cinders with a fissure, from which 

cinders erupted, between them (fig. 34). The northern 

ridge has been completely excavated, with cinders 

hauled away for railroad ballast by the Colorado and 

Southern Railway, and for manufacturing concrete 

cinder blocks and acoustical insulation (Muehlberger et 

al. 2005). 

The NPS Geologic Resources Division can provide 

monument staff with policy and technical assistance 

regarding minerals and mining. Recommendations 

include remaining aware of public and private mineral 

ownership and speculation, exploration, or drilling 

activity on lands in the vicinity of the monument. 

Regulations and permit procedures vary among states.

Figure 34. Photographs of Twin Mountain. Cinder mining takes place at Twin Mountain, about 8 km (5 mi) northeast 

of Capulin Volcano National Monument. Originally, Twin Mountain consisted of two ridges. Between 1956 (left 

photograph) and 2005 (right photograph), much of the northern ridge had been excavated. New Mexico Bureau of 

Geology and Mineral Resources photographs from Muehlberger et al. (2005, p. 5 and 55).
32

Baldwin and Muehlberger (1959) noted that cinder 

cones in the Folsom area, including Capulin Volcano, 

have been prospected for sources of cinders. In 2011, 

scoping participants identified three “test pits” that 

had been prospected within the monument, but none 

were deemed in need of restoration (KellerLynn 2011). 

These sites could be included in the NPS Abandoned 

Mineral Lands (AML) database. As of January 2015, 

no AML sites or features for Capulin Volcano National 

Monument were included in this database. Burghardt et 

al. (2014) and the NPS AML Program website

(http://go.nps.gov/grd_aml; accessed 27 January 2015) 

provides further information. The NPS Geologic 

Resources Division manages the AML database and has 

expertise to assist with restoration of past prospecting 

or mining operations, if needed in the future.

Volcano Hazards and Risk

Volcanism in the Raton-Clayton volcanic field began 

about 9 million years ago. The Capulin phase began 

1.69 million years ago. Today, the volcanic field lies 

dormant, but no evidence suggests that volcanic activity 

has ended (Sayre and Ort 1999), and future eruptions 

will likely occur (Aubele and Crumpler 2001; Walkup 

2012). A high-precision 40Ar/39Ar chronology of lateQuaternary volcanism in the Raton-Clayton volcanic 

field suggests a recurrence rate of 0 to as much as 17,000 

years for volcanism in the vicinity of Capulin Volcano 

(Zimmerer et al. 2014; Zimmerer 2015). The recurrence 

rate (i.e., eruption frequency) between the eruption of 

Malpie Mountain and Purvine Hills is one eruption per 

5,800 ± 1,000 years (i.e., five eruptions between 61,000 

± 500 and 32,000 ± 5,000 years ago). During this same 

interval, repose periods between individual eruptions 

have all been less than 17,000 years (Zimmerer et al. 

2014; Zimmerer 2015).

Most of the volcanoes within the Raton-Clayton 

volcanic field, including Capulin Volcano, are 

monogenetic, that is, they are “born,” erupt once only, 

and then “die.” Other volcanoes, known as polygenetic, 

are longer lived and erupt more than once. This is 

an important distinction for understanding future 

eruptions in the Raton-Clayton volcanic field. Future 

eruptions will likely involve the eruption of a new 

monogenetic cone, rather than an eruption taking 

place from an existing volcano (Walkup 2012). This 

reflects a basic relationship between monogenetic and 

polygenetic volcanoes. Because polygenetic volcanoes 

have a sufficiently large and persistent magma-supply 

rate, a batch of ascending magma will preferentially 

follow the still-hot pathway of the preceding batch. 

Conversely, the magma supply of a monogenetic 

volcano is so small or episodic that any pathway has 

cooled down and is no longer favored for ascension by 

the next magma batch (Walker 2000). As a result, a new 

vent will form in another location.

Analysis of new 40Ar/39Ar ages by Zimmerer et al. (2014) 

in conjunction with some previously determined 

40Ar/39Ar ages by Stroud (1997) identified vent migration 

patterns during the last 1.25 million years in the RatonClayton volcanic field (fig. 35). During this time, vent 

locations migrated to the northeast (i.e., approximately 

N74°E) at a rate of about 4.3 to 7.1 cm (1.7 to 2.8 in) 

per year. Although knowing when and where the next 

eruption in the Raton-Clayton field will take place 

is impossible, preliminary results suggest that future 

eruptions will likely occur to the east or northeast 

of Capulin Volcano National Monument. Future 

eruptions will likely be very similar to Capulin, in which 

the eruption builds a small cone with volumetrically 

minor lava flows (Zimmerer 2015). Additional work 

to understand the volcano hazards in the region is 

currently underway (Matthew Zimmerer, New Mexico 

Bureau of Geology and Mineral Resources, field 

geologist, written communication, 8 May 2015).

Walkup (2012) identified localized ash fall, earthquakes 

(as magma rises to the surface), volcanic gases, lava 

eruptions (flows), and volcanic projectiles as possible 

hazards of a future eruption in the Raton-Clayton 

volcanic field (fig. 36). Forest fires are another hazard 

that warrants mention. Pyroclastic material ejected 

from a volcano and lava flows can ignite a fire, which 

is particularly important for the desert southwest 

(Matthew Zimmerer, New Mexico Bureau of Geology 

and Mineral Resources, field geologist, written 

communication, 8 May 2015).

In the Geological Monitoring chapter about volcanoes, 

Smith et al. (2009) described seven vital signs and 

methodologies for understanding and monitoring 

volcanoes: (1) earthquake activity, (2) ground 

deformation, (3) emission at ground level, (4) emission 

of gas plumes and ash clouds, (5) hydrologic activity, 

and (6) slope instability. The NPS Geologic Resources 

Division Volcano Monitoring website (http://go.nps.

gov/monitor_volcanic; accessed 3 February 2015) 

and US Geological Survey Volcano Hazards website 
33

(http://volcanoes.usgs.gov/; accessed 3 February 2015) 

provide further information. Although the prediction of 

volcanic eruptions is not precise, monitoring allows for 

detection of changes in a volcanic field that precede an 

impending eruption. 

Geothermal Systems and Hydrothermal 

Features

The term “geothermal” refers to a system that transfers 

heat from within Earth to the surface. Where heat 

transfer involves water, hydrothermal features—such as 

hot springs, geysers, mud pots, and fumaroles—form 

at the surface and serve as indicators of an underlying 

geothermal system (Heasler et al. 2009). 

Capulin Volcano National Monument is not known 

for its geothermal resources or hydrothermal features 

and is not included on the list of 16 parks that are 

designated under the Geothermal Steam Act of 1970, 

as amended in 1988 (see Appendix B of this report). 

This act prohibits geothermal leasing in these parks, 

and authorizes the secretary of the Interior to mitigate 

or not issue geothermal leases outside parks that would 

have a significant adverse impact on significant thermal 

features within these parks. 

During the 2011 GRI scoping meeting, monument 

staff mentioned a “hot vent” near the maintenance 

building, which may be an indicator of heat transfer. 

However, nothing is documented about this “vent” and 

only anecdotal evidence exists. Locating this “vent” 

and researching information about it is a potential GIP 

project. 

In the Geological Monitoring chapter about geothermal 

systems and hydrothermal features, Heasler et al. (2009) 

described the following methods and vital signs for 

understanding geothermal systems and monitoring 

hydrothermal features: (1) thermal feature location, (2) 

thermal feature extent, (3) temperature and heat flow, 

(4) thermal water discharge, and (5) fluid chemistry. 

The NPS Geologic Resources Division Geothermal 

Systems Monitoring website, http://go.nps.gov/monitor_

geothermal (accessed 3 February 2015), provides 

additional information.

Figure 35. Maps of vent migration patterns. During the last 1.25 million years in the Raton-Clayton volcanic field, 

vent locations have migrated to the northeast. A) shows the age distribution of vents near Capulin Volcano National 

Monument. B) shows rate and direction of vent migration. MM = Malpie Mountain, CV = Capulin Volcano, BC = Baby 

Capulin, TM = Twin Mountain, and PH = Purvine Hills. Ma = millions of years; ka = thousands of years. Ages within 

blue-shaded area are from Stroud et al. (1997). All other ages are from work by Zimmerer et al. (2014) and Zimmerer 

(2015). Graphic from Zimmerer (2015, figure 1).
34

Figure 36. Schematic illustration of volcano hazards. 

A future eruption in the Raton-Clayton volcanic 

field will likely create a new cinder cone rather 

than erupting from an existing one. In addition to 

cone formation, other hazards include lava flows, 

localized ash fall, earthquakes (as magma rises 

and causes shaking), volcanic gases, and volcanic 

projectiles such as bombs. US Geological Survey 

graphic, available at http://pubs.usgs.gov/gip/64/

gip64.pdf (accessed 2 January 2014).
35

Geologic History

This chapter describes the chronology of geologic events that formed the present landscape of Capulin 

Volcano National Monument.

Capulin Volcano National Monument lies near the 

center of the Raton-Clayton volcanic field, which 

became active 9 million years ago and erupted 

episodically in three phases (fig. 8). Earliest volcanism 

took place during the Raton phase, 9.0 million–

3.5 million years ago, with most activity in the vicinity of 

Raton, New Mexico. The Clayton phase, 3.0 million–

2.2 million years ago, followed the Raton phase and 

took place in the eastern part of the field, spanning 

north to south from Mesa de Maya in Colorado to the 

Yates flows south of Gladstone, New Mexico. Volcanic 

activity at Sierra Grande occurred 3.8 million–

2.6 million years ago, overlapping in time with the Raton 

and Clayton phases. The most recent volcanism took 

place at the center of the field during the Capulin phase, 

1.69 million–32,000 years ago. The Capulin phase covers 

all activity associated with Capulin Volcano National 

Monument, including eruption of First Series lava 

flows; eruption and development of Capulin Volcano; 

and eruption of vents in the boca that produced the 

Second Series, Third Series, and Fourth Series lava 

flows (see lava flow series map, in pocket).

Raton Phase

(9.0 million–3.5 million years ago)

The earliest lavas of the Raton-Clayton volcanic field 

flowed onto a surface of sediment that had shed 

eastward from the Sangre de Cristo Mountains. This 

sediment makes up the Ogallala Formation, which has 

particular significance for the region because it contains 

the Ogallala aquifer—the major source of water for 

agricultural and domestic use in the southern High 

Plains (Gustavson 1996). Lava flows of Raton Basalt, 

formally named by Scott et al. (1990), helped to date 

the end of Ogallala deposition (Gustavson and Finley 

1985), which ties them to the geologic story of Alibates 

Flint Quarries National Monument and Lake Meredith 

National Recreation Area in the Texas Panhandle (see 

GRI report by KellerLynn in review).

Eruptions of the Raton phase consisted mostly of 

basaltic lava flows, which form the cap rock of high 

mesas in the northwestern part of the field. A peculiar 

feature of these mesa–capping lava flows is inverted 

topography where older flows are higher in elevation 

than younger flows (fig. 9). Stroud (1997) used 

this characteristic to reconstruct paleotopography 

and erosion rates of the region and concluded that 

climate change, namely a change to drier but stormier 

conditions, is the most likely cause of increased erosion. 

Red Mountain Dacite (Collins 1949; Scott et al. 1990) 

also erupted during the Raton phase, creating small 

volcanoes such as Red Mountain, Towndrow Peak (fig. 

37), Green Mountain, Laughlin Peak, and Palo Blanco 

(fig. 8). Many Raton-age features have been significantly 

eroded so that the original morphology of these 

volcanoes is no longer evident (Mathis 1999).

In addition to basalt and dacite, an important rock type 

that erupted during the Raton and Clayton phases is the 

Sierra Grande andesite (Stroud 1997). Sierra Grande 

(figs. 8 and 24) is the most prominent feature consisting 

of andesite.

Clayton Phase

(3.0 million–2.2 million years ago)

The Clayton phase produced the greatest volume of 

magma of the three phases (Mathis 1999). Most of these 

rocks occur between Clayton on the east and Sierra 

Grande on the west, though Jose Butte and Robinson 

Figure 37. Photograph of Towndrow Peak. During the 

Raton phase, dacite erupted and created lava domes 

such as Towndrow Peak. Rising 2,625 m (8,612 ft) above 

sea level, the peak sits atop Johnson Mesa. New Mexico 

Bureau of Geology and Mineral Resources photograph 

from Muehlberger et al. (2005, p. 27).
36

Peak, west of Capulin Volcano, also are Clayton age 

(Sayre and Ort 1999). This phase of volcanism is 

characterized by outpourings of lava, mostly basalt, 

some with very low amounts of silica (42%–45%; 

Stroud 1997). 

Volcanic activity of the Clayton phase began about 

3 million years ago at Rabbit Ear Mountain, which 

is near Clayton, New Mexico, and visible from the 

Crater Rim Trail on clear days. The mountain served 

as an important landmark along the Cimarron Route 

of the Santa Fe Trail. As the first peak to rise above 

the plains, Rabbit Ear Mountain was undoubtedly 

a welcome site for travelers heading west (Parent 

2006). It is 70 km (50 mi) east of Capulin Volcano. 

Over the last 3 million years, erosion has destroyed 

much of its volcanic form.

Capulin Phase

(1.69 million–32,000 years ago)

The most recent phase of volcanic activity in the 

Raton-Clayton volcanic field started 1.69 million 

years (Pleistocene Epoch; fig. 3) with the eruption 

of Mud Hill and continued after the eruption of 

Capulin Volcano (fig. 38). The age range used here 

for the Capulin phase—1.69 million to 32,000 years 

ago—is from Zimmerer (2015). New 40Ar/39Ar ages 

indicate that at least three volcanoes erupted after 

the episode that built Capulin Volcano (table 2). 

The eruption of Capulin Volcano took place 55,000 ± 

2,000 years ago and may be divided into the following 

three episodes: (1) First Series lava flows, (2) conebuilding eruption, and (3) boca eruption from which 

the Second Series, Third Series, and Fourth Series flows 

emerged.

First Series Lava Flows

Initially, lava associated with Capulin Volcano simply 

spread across the landscape. It erupted from a fissure 

Figure 38. Satellite imagery of Capulin phase volcanoes. The 

Capulin phase of the Raton-Clayton volcanic field occurred 

1.69 million–32,000 years ago. Capulin Volcano erupted 

about 55,000 years ago. Northeast of Capulin Volcano, Mud 

Hill erupted 1.69 million years ago and is, therefore, notably 

older than the surrounding volcanoes. Baby Capulin erupted 

46,000 years ago and is thus younger than Capulin Volcano. 

The green outline delineates the boundary of Capulin Volcano 

National Monument. Landsat imagery (May 2014) extracted 

from Google Earth.

Table 2. 40Ar/39Ar ages for Capulin and surrounding volcanoes

Volcano Age (years ago) Comments from Zimmerer (2015)

Purvine Hills 32,000 ± 5,000 Youngest known eruption in the Raton-Clayton volcanic field. Age agrees with Sayre and Ort (1999) 

that suggested Purvine Hills are also younger than Capulin Volcano.

Twin Mountain 40,000 ± 4,000

New age agrees with previously determined 40Ar/39Ar ages of 48,000 ± 20,000 years ago from Stroud 

(1997). Ages agree with Sayre and Ort (1999) that suggested Twin Mountain is younger than Capulin 

Volcano.

Baby Capulin 46,000 ± 6,000 Age agrees with stratigraphy that suggests Baby Capulin is younger than Capulin Volcano. Flows from 

Baby Capulin traveled approximately 30 km (20 mi) down the Dry Cimarron River.

Capulin 55,000 ± 2,000

Agrees with previous age determinations, but new age is significantly more precise. New age is from 

sample of lava lake in the boca. An additional age from the crater (51,000 ± 5,000 years ago) agrees 

with the boca age, but is less precise.

Malpie Mountain 61,000 ± 500 Located south of Capulin Volcano National Monument. Very precise date.

Mud Hill 1,690,000 ± 30,000 Significantly older than surrounding volcanoes
37

or series of small vents, then flowed east to form the 

First Series lava flows (Sayre and Ort 1999). A mantle of 

cinders covers these flows, indicating that First Series 

lava had been emplaced before the construction of 

Capulin Volcano.

Cone-Building Eruption

Capulin Volcano built up quickly, in a matter of weeks 

to years (Sayre and Ort 1999). It was the second and 

most dramatic part of the volcano’s eruption. The initial 

fissure or series of small vents coalesced into a single 

vent from which exploding gases propelled lava into 

the air. The eruption built up the cone from the ground 

surface as primarily cinders, but bombs and ash also 

accumulated around the vent. Repeated explosions 

kept the crater clear. When the slope of the growing 

pyroclastic pile became too steep, cinders and ash slid 

downward, forming distinctive layers (fig. 12). Prevailing 

southwesterly winds caused cinders to pile up higher on 

the northeastern side of the crater (fig. 25). As expulsion 

of volcanic gases waned, spatter was deposited on the 

rim and crater, marking the end of the cone-building 

episode (fig. 39). 

Boca Eruption

After cone building, volcanism shifted to the boca on 

the western side of the cinder cone (see cover). The 

absence of cinders on top of volcanic features in the 

boca indicates that activity in the boca followed the 

cone-building eruption. During the boca eruption, 

lava extruded from multiple vents, two of which are 

included in the GRI GIS data set (see lava flow series 

map, in pocket). During the boca eruption, lava flowed 

to the southeast in Second Series lava flows, then to the 

southwest in Third Series lava flows, and finally north 

in Fourth Series lava flows. Many features were created 

while lava erupted from the boca, including boca 

ramparts lava, lava lakes, levees, push-ups, rafted cinder 

cones, spatter deposits, spatter flows, lava cascades, lava 

ridges, squeeze-ups, and tumuli (see volcanic features 

map and Map Unit Properties Table, in pocket).

Second Series Lava Flows

Second Series lava flows oozed out of the side of the 

cinder cone, traveling south down a narrow valley 

through what is now the picnic area at Capulin Volcano 

National Monument. A lava tube, squeeze-ups, and 

tumuli formed during this series, which ended when 

Figure 39. Panoramic views of Capulin crater and vent. From the Crater Rim Trail (upper photograph), visitors can look 

into Capulin crater. The view is from just north of the crater parking area. The lower photograph shows the rim from 

within the crater; it was taken near the vent. Note the irregular, jagged spatter that coats most of the inner walls 

of the crater and vent region. The paved pathway of Crater Vent Trail can be seen in the foreground. Photographs 

by Matthew Zimmerer (MattZPhotography, www.mattzphotography.com [accessed 11 September 2015], used with 

permission), processed using Adobe Lightroom and stitched together using Hugin.
38

a chunk of the cinder cone rafted away from the main 

cone and blocked egress. This piece of cinder cone—the 

southern of the two rafted cinder cones mapped by 

Richman (2010)—is visible as the hill northwest of the 

hairpin turn near the picnic area. It is made of cinders 

and spatter.

Third Series Lava Flows

Following emplacement of Second Series lava flows, the 

presently visible lava lake system of the boca began to 

develop. Lava that fed this system came from the more 

southerly of the two vents in the boca (see volcanic 

features map, in pocket). Spatter extensively covers this 

vent area. Third Series lava formed a pair of lakes near 

the old campfire chimney in the boca (figs. 16 and 17), 

then traveled by lava tubes down to the area near the 

visitor center, where tumuli formed. From there, Third 

Series lava flows traveled via tubes and open flows 

down toward what is now the town of Capulin, and to 

the west. The lakes themselves were bounded by walls 

made of spatter and solidified lava from the edges of the 

flows. As time went by, these lakes were cut off from the 

vent, perhaps during a brief eruptive hiatus (Sayre and 

Ort 1999).

Fourth Series Lava Flows

Fourth Series lava erupted from the more northerly of 

the two vents in the boca (see volcanic features map, in 

pocket). The lava again filled a lava lake that eventually 

began to drain to the north, aided by lava tubes. This 

part of the eruption ceased when a large piece of 

the cinder cone rafted out about 100 m (300 ft). As a 

result, lavas subsequently extruded from the northeasternmost edge of the boca and then covered the area 

between Capulin Volcano and Mud Hill, and to the east 

on top of Mud Hill deposits. This rafted piece of cinder 

cone forms a ridge at the northern end of the boca that 

is clearly visible from the highway traveling southward.

The eruption of Capulin Volcano only lasted a short 

time, probably weeks to years, which is common for 

volcanoes of this type. In cinder-cone eruptions, 

the supply of magma is small or episodic, facilitating 

the cooling and clogging of a vent and subterranean 

pathway. As new magma forces its way up through 

the Earth’s crust, a different vent will form, creating a 

new volcano. Although Capulin Volcano is unlikely to 

erupt again, molten rock may once again flow across 

the plains of northeastern New Mexico from a newly 

formed vent in the Raton-Clayton volcanic field.
39

Geologic Map Data

This chapter summarizes the geologic map data available for Capulin Volcano National Monument. 

Two posters (in pocket) display the GRI GIS data draped over imagery of the monument and 

surrounding area. The Map Unit Properties Table (in pocket) summarizes this report’s content for each 

geologic map unit. Complete GIS data are available at the GRI publications website: http://go.nps.gov/

gripubs.

Geologic Maps

Geologic maps facilitate an understanding of an area’s 

geologic framework and the evolution of its present 

landscape. Using designated colors and symbols, 

these maps portray the spatial distribution and 

temporal relationships of rocks and unconsolidated 

deposits. Geologic maps can be divided into two 

primary types: surficial and bedrock. Surficial 

geologic maps typically encompass deposits that are 

unconsolidated and formed during the past 2.6 million 

years (the Quaternary Period). Surficial map units 

are differentiated by geologic process or depositional 

environment. Bedrock geologic maps encompass 

older, typically more consolidated sedimentary, 

metamorphic, and/or igneous rocks. Bedrock map units 

are differentiated based on age and/or rock type.

Geologic maps often depict geomorphic features, 

structural interpretations (such as faults or folds), 

and locations of past geologic hazards that may be 

susceptible to future activity. Anthropogenic features 

such as mines or quarries, as well as observation or 

collection locations, may be indicated on geologic maps. 

The American Geosciences Institute website,

http://www.agiweb.org/environment/publications/

mapping/index.html (accessed 3 February 2015), 

provides more information about geologic maps and 

their uses. 

Source Maps

The GRI team digitizes paper maps and converts digital 

data to conform to the GRI GIS data model. GRI digital 

geologic map products include essential elements 

of the source maps such as map unit descriptions, a 

correlation chart of units, a map legend, map notes, 

references, and figures. The GRI team used the 

following source to produce the GRI GIS data for 

Capulin Volcano National Monument.

Richman, R. 2010. Digital volcanic geology of Capulin 

Volcano National Monument and vicinity (scale 1:24,000). 

Prepared by Student Conservation Association (SCA) 

geology and interpretation intern for Capulin Volcano 

National Monument, Capulin, New Mexico. 

During mapping and report preparation, Richman 

(2010) used the following sources:

Mathis, A. 1999. Volcanology for interpreters. Unpublished 

geology guide. Capulin Volcano National Monument, 

Capulin, New Mexico.

Sayre, W. O., and M. H. Ort. 1999. A geologic study of Capulin 

Volcano National Monument and surrounding areas. 

Final report. Cooperative Agreement CA7029-1-0017 (4 

December 1999). Submitted to Capulin Volcano National 

Monument, Capulin, New Mexico. College of Santa Fe, 

and Northern Arizona University, Santa Fe, New Mexico, 

and Flagstaff, Arizona. Published as Open-File Report 

541 (August 2011). New Mexico Bureau of Geology and 

Mineral Resources, Socorro, New Mexico. http://geoinfo.

nmt.edu/publications/openfile/downloads/OFR500-

599/526-550/541/ofr_541.pdf (accessed 29 October 2014).

Sayre, W. O., M. H. Ort, and D. Graham. 1995. Capulin 

Volcano is approximately 59,100 years old: cosmogenic 

helium aging technique key to clearing up age old question. 

Park Science 15(2):10–11. http://www.nature.nps.gov/

parkscience/archive/PDF/ParkScience15(2)Spring1995.pdf 

(accessed 4 November 2014).

GRI GIS Data

The GRI team implements a GIS data model that 

standardizes map deliverables. The data model is 

available at http://go.nps.gov/gridatamodel. This data 

model dictates GIS data structure, including layer 

architecture, feature attribution, and relationships 

within ESRI ArcGIS software. The GRI team digitized 

the data for Capulin Volcano National Monument 

using data model version 2.1. The GRI Geologic Maps 

website, http://go.nps.gov/geomaps, provides more 

information about GRI map products. 
40

GRI digital geologic data are available through the NPS 

Integrated Resource Management Applications (IRMA) 

portal (https://irma.nps.gov/App/Portal/Home). Enter 

“GRI” as the search text and select a park.

The GRI GIS data set for Capulin Volcano National 

Monument includes two parts: (1) cavo_geology.mxd, 

which contains volcanic features within the monument 

mapped by Richman (2010); and (2) cvlf_geology.mxd, 

which shows the full extent of the four series of lava 

flows and vents associated with Capulin Volcano, and 

also delineates Mud Hill and Baby Capulin and their 

vents. The following components are part of the data 

set:

● A GIS readme file (cavo_gis_readme.pdf) 

that describes the GRI data formats, naming 

conventions, extraction instructions, use 

constraints, and contact information.

● Data in ESRI geodatabase GIS format;

● Layer files with feature symbology (tables 3 and 4);

● Federal Geographic Data Committee–compliant 

metadata;

● An ancillary map information document (cavo_

geology.pdf) that contains information captured 

from source maps;

● An ESRI map document (cavo_geology.mxd; 

cvlf_geology.mxd) that displays the digital geologic 

data; and

● A KML/KMZ version of the data viewable in 

Google Earth (tables 3 and 4).

GRI Map Posters

Two posters are included with the GRI report for 

Capulin Volcano National Monument. One displays 

the digital volcanic features map of the monument 

and vicinity, detailing the boca. These data are part of 

cavo_geology.mxd. The other displays the digital lava 

flows and vents of the Capulin Volcano area. In addition 

to the main cone and boca, this poster shows the extent 

of the four series of lava flows, Mud Hill, and Baby 

Capulin, as well as vents. These data are part of cvlf_

geology.mxd. Both posters illustrate the GRI GIS data 

draped over a shaded relief image of the monument 

and surrounding area. Geographic information and 

selected features at the monument have been added to 

the posters. Digital elevation data and added geographic 

information are not included in the GRI GIS data 

set, but are available from a variety of online sources. 

Contact GRI for assistance locating these data.

Map Unit Properties Tables

The Map Unit Properties Table is organized 

stratigraphically (younger on top of older units) 

following the lava flow series data and timing of 

eruptions established by Sayre and Ort (1999). The 

table correlates specific volcanic features mapped by 

Richman (2010) to their corresponding lava flow series. 

The table lists the geologic time division, map symbol, 

and a simplified description for each of the volcanic 

features in the GRI GIS data. Detailed descriptions of 

these volcanic features are included in the “Volcanic 

Features” section of this report. Following the structure 

of the report, the table summarizes the geologic features 

and processes, resource management issues, and history 

associated with each map unit. 

Use Constraints

Graphic and written information provided in this 

report is not a substitute for site-specific investigations. 

Ground-disturbing activities should neither be 

permitted nor denied based upon the information 

provided here. Please contact the GRI team with any 

questions. Minor inaccuracies may exist regarding the 

locations of geologic features relative to other geologic 

or geographic features on the posters. Based on the 

source map scale (1:24,000) and US National Map 

Accuracy Standards, geologic features represented in 

the geologic map data are horizontally within 12 m (40 

ft) of their true locations.

Table 3. GRI GIS data layers of cavo_geology.mxd (volcanic 

features map of Capulin Volcano National Monument)

Data Layer On Poster? Google Earth 

Layer?

Volcanic Point Features Yes No

Volcanic Line Features Yes Yes

Volcanic Area Feature 

Boundaries

Yes Yes

Volcanic Area Features Yes Yes

Table 4. GRI GIS data layers of cvlf_geology.mxd (lava flow 

series of Capulin Volcano area)

Data Layer On Poster? Google Earth 

Layer?

Vent Point Features Yes No

Volcanic Flow Unit Boundaries Yes Yes

Volcanic Flow Units Yes Yes
41

Glossary

These are brief definitions of selected geologic terms relevant to this report. Definitions are based on 

those in the American Geosciences Institute Glossary of Geology (5th edition; 2005). Additional terms 

are defined at http://geomaps.wr.usgs.gov/parks/misc/glossarya.html.

aeolian. Describes materials formed, eroded, or deposited 

by or related to the action of wind. 

agglomerate. A consolidated pyroclastic rock made 

primarily of bombs. Roughly synonymous with spatter.

agglutinate. A welded pyroclastic deposit characterized by 

vitric material binding the individual clasts that commonly 

became fused while hot and viscous.

alkali. Describes silicate (silicon + oxygen) minerals that 

contain alkali metals such as sodium and potassium. 

alkali metals. Any of the soft, white, low-density, lowmelting, highly reactive metallic elements, including 

lithium, sodium, potassium, rubidium, cesium, and 

francium, belonging to Group 1A of the periodic table.

alluvium. Stream-deposited sediment.

andesite. A volcanic rock characteristically medium dark in 

color and containing approximately 57%–63% silica and 

moderate amounts of iron and magnesium.

ash. Fine-grained material, less than 2 mm (0.08 in) across, 

ejected from a volcano.

basalt. A volcanic rock that is characteristically dark in color 

(gray to black), contains approximately 53% silica or less, 

and is rich in iron and magnesium.

basaltic andesite. A volcanic rock that is commonly dark 

gray to black and contains approximately 53%–57% silica.

bedrock. Solid rock that underlies unconsolidated 

sedimentary deposits and soil.

block. A pyroclast ejected in a solid state; it has a diameter 

greater than 64 mm (2.5 in).

bomb. A viscous pyroclast more than 64 mm (2.5 in) in 

diameter ejected then shaped while in flight; it commonly 

has a hollow or vesicular interior.

breakdown. Collapse of a cave ceiling or walls of a cave. 

Also, the accumulation of debris thus formed.

caldera. A large, basin-shaped volcanic depression formed 

by collapse during an eruption.

channel. The bed where a natural body of surface water 

flows or may flow. Also, a natural passageway or 

depression of perceptible extent containing continuously 

or periodically flowing water, or forming a connecting link 

between two bodies of water.

chronology. The arrangement of events in their proper 

sequence in time.

cinder. A glassy, vesicular, pyroclastic fragment that falls to 

the ground in an essentially solid condition.

cinder cone. A conical hill, commonly steep, ranging 

from tens to hundreds of meters tall, formed by the 

accumulation of solidified fragments of lava that fell 

around the vent during a basaltic or andesitic eruption. 

clast. An individual constituent, grain, or fragment of a rock 

or unconsolidated deposit, produced by the mechanical 

or chemical disintegration of a larger rock mass.

composite volcano. Steep, conical volcanoes built by the 

eruption of viscous lava flows, tephra, and pyroclastic 

flows; usually constructed over tens to hundreds of 

thousands of years and may erupt a variety of magma 

types (basalt to rhyolite); typically consist of many 

separate vents. Synonymous with “stratovolcano.”

crust. Earth’s outermost layer or shell. 

dacite. A volcanic rock that is characteristically light in 

color and contains approximately 63%–68% silica and 

moderate amounts of sodium and potassium. 

debris flow. A moving mass of rock fragments, soil, and 

mud, with more than half of the particles larger than sand 

size. Slow debris flows may move less that 1 m (3 ft) per 

year; rapid ones reach 160 kph (100 mph). 

discharge. The rate of flow of surface water or groundwater 

at a given moment, expressed as volume per unit of time.

drainage. The manner in which the waters of an area flow 

off in surface streams or subsurface conduits; also, the 

processes of surface drainage of water from an area by 

streamflow and sheet flow, and the removal of excess 

water from soil by downward flow.

dune. A low mound or ridge of sediment, usually sand, 

deposited by the wind. 

ephemeral lake. A short-lived lake.

erosion. The general process or group of processes that 

loosen, dissolve, wear away, and simultaneously move 

from one place to another, the materials of Earth’s crust; 

includes weathering, solution, abrasive actions, and 

transportation, but usually excludes slope movements.

fissure. A fracture or crack in rock along which there is a 

distinct separation; commonly filled with mineral-bearing 

materials. 

fissure (volcanic). An elongated fracture or crack at the 

surface from which lava erupts.

fissure vent. A volcanic conduit having the form of a crack 

or fissure at Earth’s surface.

fissure volcano. One of a series of volcanic vents in a pattern 

of eruption along a fissure.

fluvial. Of or pertaining to a river or rivers.

formation. Fundamental rock-stratigraphic unit that is 

mappable, lithologically distinct from adjoining strata, 

and has definable upper and lower contacts.

fossil. A remain, trace, or imprint of a plant or animal that 

has been preserved in the Earth’s crust since some past 

geologic time; loosely, any evidence of past life.

fumarole. A vent, usually volcanic, from which gases and 

vapors are emitted. 
42

geology. The study of Earth, including its origin, history, 

physical processes, components, and morphology.

geothermal. Pertaining to the heat of the interior of the 

Earth.

groundwater. That part of subsurface water that is in the 

zone of saturation, including underground streams.

horizon (archeology). A period during which the influence 

of a specific culture spread rapidly over a defined area. 

hornito. A small mound of spatter built on the back of a lava 

flow, formed by the gradual accumulation of lava clots 

ejected through an opening in the roof of an underlying 

lava tube.

hydrothermal. Of or pertaining to hot water, to the action of 

hot water, or to the products of this action. 

hydrovolcanic. Term encompassing all volcanic activity that 

results from the interaction between lava, magmatic heat, 

or gases and water at or near the surface of the Earth. 

Synonymous with “phreatomagmatic.”

igneous. Describes a rock or mineral that solidified 

from molten or partly molten material; also, describes 

processes leading to, related to, or resulting from the 

formation of such rocks. One of the three main classes or 

rocks—igneous, metamorphic, and sedimentary.

isotopic age. An age (in years) calculated from the 

quantitative determination of radioactive elements and 

their decay products. 

isotopic dating. Calculating an age in years for geologic 

materials by measuring the presence of a short-lived 

radioactive element (e.g., carbon-14) or by measuring the 

presence of a long-lived radioactive element plus its decay 

product (e.g., potassium-40/argon-40). The term applies 

to all methods of age determination based on nuclear 

decay of naturally occurring radioactive isotopes.

landslide. A collective term covering a wide variety of 

slope-movement landforms and processes that involve the 

downslope transport of soil and rock material en masse 

under the influence of gravity.

lapilli. Pyroclastic materials ranging between 2 and 64 mm 

(0.08 and 2.5 in) across with no characteristic shape; 

may be either solidified or still viscous upon landing. An 

individual fragment is called a lapillus.

lava. Molten or solidified magma that has been extruded 

though a vent onto Earth’s surface.

lava dome. A steep-sided mass of viscous, commonly 

blocky, lava extruded from a vent; typically has a rounded 

top and covers a roughly circular area; may be isolated or 

associated with lobes or flows of lava from the same vent; 

typically silicic (rhyolite or dacite) in composition.

lava lake. A lake of molten lava, usually basaltic, in a volcanic 

crater or depression. Also refers to solidified and partly 

solidified stages.

lava tube. Conduits through which lava travels beneath the 

surface of a lava flow; also, a cavernous segment of the 

conduit remaining after the flow of lava ceases.

levee (volcanic). A retaining wall of hardened lava alongside 

a lava channel; also, the freestanding cooled edge of a lava 

tongue or flow left after evacuation of the molten lava.

loess. Windblown silt-sized sediment.

maar. A low-relief, broad volcanic crater formed by multiple 

shallow explosive eruptions. It is surrounded by a lowrelief rim of fragmental material, and may be filled by 

water.

magma. Molten rock beneath Earth’s surface capable of 

intrusion and extrusion. 

mesa. A broad, flat-topped erosional hill or mountain with 

by steeply sloping sides or cliffs.

metamorphic rock. Any rock derived from preexisting 

rocks that was altered in response to marked changes 

in temperature, pressure, shearing stress, and chemical 

environment. One of the three main classes of rock—

igneous, metamorphic, and sedimentary.

mineral. A naturally occurring inorganic crystalline solid 

with a definite chemical composition or compositional 

range.

mold. An impression made in the surrounding earth by 

the exterior or interior of a fossil shell or other organic 

structure and then preserved. Also, a cast of the inner 

surface of a fossil shell.

outcrop. Any part of a rock mass or formation that is 

exposed or “crops out” at Earth’s surface. 

paleontology. The study of the life and chronology of 

Earth’s geologic past based on the fossil record.

period. The fundamental unit of the worldwide geologic 

time scale. It is lower in rank than era and higher than 

epoch. The geochronologic unit during which the rocks of 

the corresponding system were formed.

phreatomagmatic. See “hydrovolcanic.”

playa. A dry, vegetation-free, flat area at the lowest part of an 

undrained desert basin.

playa lake. A shallow, intermittent lake in an arid region, 

covering up or occupying a playa in the wet season but 

subsequently drying up.

pumice. A highly vesicular pyroclast with very low bulk 

density and thin vesicle walls.

pyroclast. An individual particle ejected during a volcanic 

eruption; usually classified according to size.

pyroclastic. Describes clastic rock material formed by 

volcanic explosion or aerial expulsion from a vent; also, 

describes a rock texture of explosive origin. It is not 

synonymous with “volcanic.”

radiocarbon age. An isotopic age expressed in years and 

calculated from the quantitative determination of the 

amount of carbon-14 remaining in an organic material. 

Synonymous with “carbon-14 age.”

relative dating. The chronological placement and ordering 

of rocks, events, or fossils with respect to the geologic 

time scale and without reference to numerical ages.

rhyodacite. A volcanic rock that contains approximately 

68%–72% silica and is intermediate in composition 

between rhyolite and dacite.

rhyolite. A volcanic rock that is characteristically light in 

color, contains approximately 72% or more of silica, and 

is rich in potassium and sodium. 

rift. A region of Earth’s crust where extension results in 

formation of many related normal faults, commonly 

associated with volcanic activity.
43

rill. A very small brook or trickling stream of water usually 

without any tributaries. Also, the channel formed by such 

a stream.

rock. An aggregate of one or more minerals (e.g., granite), a 

body of undifferentiated mineral matter (e.g., obsidian), 

or a body of solid organic material (e.g., coal).

rockfall. The most rapid type of slope movement in which a 

newly detached fragment of bedrock of any size falls from 

a cliff or other very steep slope, traveling straight down or 

in a series of leaps and bounds down a slope.

sand sheet. A sheetlike body of surficial sediment, 

commonly sand, that veneers the underlying stratigraphic 

units (unconsolidated deposits or bedrock) and can range 

in thickness from a few centimeters to tens of meters, with 

a lateral persistence of a few meters to tens of kilometers.

sandstone. Clastic sedimentary rock composed of 

predominantly sand-sized grains.

sediment. An eroded and deposited, unconsolidated 

accumulation of rock and mineral fragments.

sedimentary. Pertaining to or containing sediment. 

sedimentary rock. A rock resulting from the consolidation 

of loose sediment that has accumulated in layers; it may 

be “clastic,” consisting of mechanically formed fragments 

of older rock; “chemical,” formed by precipitation from 

solution; or “organic,” consisting of the remains of plants 

and animals. One of the three main classes of rock—

igneous, metamorphic, and sedimentary. 

shale. A clastic sedimentary rock made of clay-sized 

particles and characterized by fissility.

sheet erosion. The removal of thin layers of surface material 

more or less evenly from an extensive area of gently 

sloping land by broad continuous sheets of running water, 

rather than by streams flowing in well-defined channels.

shield volcano. A broad shield-shaped volcano that is built 

up by successive, mostly effusive, eruptions of low-silica 

lava.

sierra. A high range of hills or mountains, especially one 

having jagged or irregular peaks that resemble the teeth of 

a saw.

silica. Silicon dioxide, SiO2, an essential constituent of many 

minerals, occurring as crystalline quartz, cryptocrystalline 

chalcedony, and amorphous opal.

silt. Clastic sedimentary material intermediate in size 

between fine-grained sand and coarse clay, 0.0039 to 

0.063 mm (0.00015 to 0.0025 in) across.

slope. The inclined surface of any part of Earth’s surface, 

such as a hillslope. Also, a broad part of a continent 

descending into an ocean.

slope movement. The gradual or rapid downslope 

movement of soil or rock under gravitational stress. 

Synonymous with “mass wasting.”

soil. The unconsolidated portion of the Earth’s crust 

modified through physical, chemical, and biotic processes 

into a medium capable of supporting plant growth.

spatter. An accumulation of initially very fluid pyroclasts, 

usually stuck together, coating the surface around a vent.

spatter cone. A low, steep-sided cone of spatter built up on a 

fissure or vent, usually composed of basaltic material.

squeeze-up. A small accumulation of viscous lava extruded 

under pressure from a fracture or opening onto the 

solidified surface of a lava flow.

strata. Tabular or sheetlike layers of sedimentary rock 

that are visually distinctive from other layers above and 

below. The singular form of the term is stratum, but is less 

commonly used.

stratigraphic. Of or pertaining to strata.

stratigraphy. The geologic study of the origin, occurrence, 

distribution, classification, correlation, and age of rock 

layers, especially sedimentary rocks.

stratotype. The original or subsequently designated 

standard of reference of a named layered stratigraphic 

unit or of a stratigraphic boundary; a specific interval or 

point in a specific sequence of rock strata that constitutes 

the standard of the definition and characterization 

of the stratigraphic unit or boundary being defined. 

Synonymous with “type section.”

stratovolcano. A volcano that is constructed of alternating 

layers of lava and pyroclastic deposits, along with 

abundant dikes and sills. Viscous, high-silica lava may 

flow from fissures radiating from a central vent, from 

which pyroclastic material is ejected. Synonymous with 

“composite volcano.”

stream. Any body of water moving under gravity flow in a 

clearly confined channel.

tephra. A collective term used for all pyroclastic material, 

regardless of size, shape, or origin, ejected into the air 

during a volcanic eruption.

topography. The general morphology of Earth’s surface, 

including relief and locations of natural and human-made 

features.

trace fossil. A fossilized feature such as a track, trail, 

burrow, or coprolite (dung), that preserves evidence of an 

organism’s life activities, rather than the organism itself. 

Compare to “body fossil.”

tree mold. A cylindrical hollow in a lava flow formed by the 

envelopment of a tree by the flow, solidification of the lava 

in contact with the tree, and disappearance of the tree by 

burning and subsequent removal of the charcoal and ash. 

The inside of the mold preserves the surficial features of 

the tree. 

tuff. Consolidated or cemented volcanic ash and lapilli.

tumulus. A dome or small mound on the crust of a lava 

flow, caused by pressure due to the difference in the rate 

of flow between the cooler lava crust and the more fluid 

underlying lava.

type area. The geographic area or region that encompasses 

the stratotype or type locality of a stratigraphic unit or 

stratigraphic boundary.

type section. The originally described sequence of strata 

that constitute a stratigraphic unit. It serves as an objective 

standard with which spatially separated parts of the unit 

may be compared, and it is preferably in an area where 

the unit shows maximum thickness and is completely 

exposed (or at least shows top and bottom).

undercutting. The removal of material at the base of a steep 

slope by the erosive action of water (such as a meandering 

stream), sand-laden wind in a desert, or waves along a 

coast.
44

vent. Any opening at Earth’s surface through which magma 

erupts or volcanic gases are emitted.

vesicle. A cavity of variable shape formed by the entrapment 

of a gas bubble during solidification of lava.

vesicular. Describes the texture of a rock, especially lava, 

characterized by abundant vesicles formed as a result of 

the expansion of gases during the fluid stage of a lava.

viscosity. The property of a substance to offer internal 

resistance to flow.

volcanic. Pertaining to the activities, structures, or rock types 

of a volcano. A synonym of extrusive.

volcanism. The processes by which magma and its 

associated gases rise into Earth’s crust and are extruded 

onto the surface and into the atmosphere.

weathering. The physical, chemical, and biological 

processes by which rock is broken down, particularly at 

Earth’s surface.

welding. Consolidation of sediments under pressure. Also, 

the diagenetic process whereby discrete crystals and/or 

grains become attached to each other during compaction. 

xenocryst. A crystal that resembles a phenocryst in igneous 

rock but is foreign to the body of rock in which it occurs.

xenolith. A rock particle, formed elsewhere, entrained in 

magma as an inclusion.
45

Literature Cited

These references are cited in this report. Contact the Geologic Resources Division for assistance in 

obtaining them.

Anderson, A. D., and C. V. Haynes Jr. 1979. How old is Capulin Mountain? Correlation between Capulin Mountain volcanic flows 

and the Folsom type site, northeastern New Mexico. Pages 893–899 in R. M. Linn, editor. Proceedings of the First Conference on 

Scientific Research in the National Parks. Volume II. Transactions and Proceedings Series 5. National Park Service, Washington, 

DC. https://ia601503.us.archive.org/2/items/proceedingsoffir00vol2/proceedingsoffir00vol2.pdf (accessed 4 November 2014).

Anderson, R. S., and T. R. Van Devender. 1995. Vegetation history and paleoclimates of the coastal lowlands of Sonora, Mexico—

pollen records from packrat middens. Journal of Arid Environments 30:295–306.

Aubele, J. C., and L. S. Crumpler. 2001. Raton-Clayton and Ocate volcanic fields. Pages 69–76 in S. G. Lucas and D. Ulmer-Scholle, 

editors. Geology of the Llano Estacado. Fall Field Conference Guidebook 52. New Mexico Geological Society, Socorro, New 

Mexico. https://nmgs.nmt.edu/publications/guidebooks/downloads/52/52_p0069_p0076.pdf (accessed 9 October 2014).

Baldwin, B., and W. R. Muehlberger. 1959 (reprinted 1981). Geology of northwestern Union County, New Mexico (scale 1:125,000). 

Plate 1b in Geologic studies of Union County, New Mexico. Bulletin 63. New Mexico Bureau of Geology and Mineral Resources, 

Socorro, New Mexico. http://ngmdb.usgs.gov/Prodesc/proddesc_90715.htm (accessed 3 August 2015).

Bauman, S. L. 1999. Spatial variability of desert loess on the Carrizozo lava flow, south-central New Mexico. Thesis. New Mexico 

Institute of Mining and Technology, Socorro, New Mexico. 

Bemis, K., J. Walker, A. Borgia, B. Turrin, M. Neri, and C. Swisher. 2011. The growth and erosion of cinder cones in Guatemala and 

El Salvador: models and statistics. Journal of Volcanology and Geothermal Research 201:39–52. 

Bennetts, R. E., K. Struthers, P. Valentine-Darby, T. Folts, H. Sosinski, and E. Yost. 2012. Capulin Volcano National Monument: 

natural resource condition assessment. Natural Resource Report NPS/SOPN/NRR—2012/492. National Park Service, Fort 

Collins, Colorado. http://nature.nps.gov/publications/NRPM/nrr.cfm (accessed 18 November 2014).

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Additional References

This chapter lists additional references, resources, and websites that may be of use to resource 

managers. Web addresses are valid as of August 2015. Refer to Appendix B for laws, regulations, and 

policies that apply to NPS geologic resources.

Geology of National Park Service Areas

● NPS Geologic Resources Division

Energy and Minerals; Active Processes and Hazards; 

Geologic Heritage:

http://nature.nps.gov/geology/

● NPS Geologic Resources Inventory: http://www.

nature.nps.gov/geology/inventory/index.cfm

● NPS Geoscientist-In-the-Parks (GIP) internship 

and guest scientist program:

http://www.nature.nps.gov/geology/gip/index.cfm

● NPS Views program (geology-themed modules are 

available for Geologic Time, Paleontology, Glaciers, 

Caves and Karst, Coastal Geology, Volcanoes, and a 

variety of geologic parks):

http://www.nature.nps.gov/views/

● USGS Geology of National Parks (including 3D 

imagery): http://3dparks.wr.usgs.gov/

NPS Resource Management Guidance and 

Documents

● Management Policies 2006 (Chapter 4: Natural 

resource management):

http://www.nps.gov/policy/mp/policies.html

● 1998 National parks omnibus management act: 

http://www.gpo.gov/fdsys/pkg/PLAW-105publ391/

pdf/PLAW-105publ391.pdf

● NPS-75: Natural resource inventory and 

monitoring guideline:

http://www.nature.nps.gov/nps75/nps75.pdf

● NPS Natural resource management reference 

manual #77: http://www.nature.nps.gov/Rm77/

● Geologic monitoring manual (Young, R., and 

L. Norby, editors. 2009. Geological monitoring. 

Geological Society of America, Boulder, Colorado): 

http://nature.nps.gov/geology/monitoring/index.

cfm

● NPS Technical Information Center (TIC) (Denver, 

Colorado; repository for technical documents): 

http://www.nps.gov/dsc/technicalinfocenter.htm

Climate Change Resources

● NPS Climate Change Response Program Resources: 

http://www.nps.gov/subjects/climatechange/

resources.htm

● US Global Change Research Program:

http://globalchange.gov/home

● Intergovernmental Panel on Climate Change:

http://www.ipcc.ch/

Geological Surveys and Societies

● New Mexico Bureau of Geology and Mineral 

Resources: http://geoinfo.nmt.edu/

● US Geological Survey: http://www.usgs.gov/

● Geological Society of America:

http://www.geosociety.org/

● American Geophysical Union: http://sites.agu.org/

● American Geosciences Institute:

http://www.americangeosciences.org/

● Association of American State Geologists:

http://www.stategeologists.org/

US Geological Survey Reference Tools

● National geologic map database (NGMDB):

http://ngmdb.usgs.gov/

● Geologic names lexicon (GEOLEX; geologic unit 

nomenclature and summary):

http://ngmdb.usgs.gov/Geolex/geolex_home.html

● Geographic names information system (GNIS; 

official listing of place names and geographic 

features): http://gnis.usgs.gov/

● GeoPDFs (download searchable PDFs of any 

topographic map in the United States):

http://store.usgs.gov (click on “Map Locator”)

● Publications warehouse (many publications 

available online): http://pubs.er.usgs.gov

● Tapestry of time and terrain (descriptions of 

physiographic provinces):

http://tapestry.usgs.gov/Default.html

53

Appendix A: Scoping Participants

The following people attended the GRI scoping meeting for Capulin Volcano National Monument, 

held on 10 May 2011. Discussions during these meetings supplied a foundation for this GRI report. The 

scoping summary document is available on the GRI publications website: http://go.nps.gov/gripubs.

Name Affiliation Position

Peter Armato Capulin Volcano National Monument Superintendent 

Rob Bennetts NPS Southern Plains Network Network Coordinator 

Lynn Cartmell Capulin Volcano National Monument Lead Park Ranger 

Tim Connors NPS Geologic Resources Division Geologist 

Nelia Dunbar New Mexico Bureau of Geology and Mineral Resources Geologist 

Bruce Heise NPS Geologic Resources Division Geologist/Program Coordinator 

Adam Heberlie Bent’s Old Fort National Historic Site Biological Sciences Technician 

Katie KellerLynn Colorado State University Geologist/Research Associate

Bill McIntosh New Mexico Bureau of Geology and Mineral Resources Volcanologist 

Fran Pannebaker Bent’s Old Fort National Historic Site Chief of Resources 

Phil Reiker NPS Geologic Resources Division Geologist/Writer-Editor 

Karl Zimmerman Sand Creek Massacre National Historic Site Chief of Resources and Operations 

55

Appendix B: Geologic Resource Laws, Regulations, and Policies

The NPS Geologic Resources Division developed this table to summarize laws, regulations, and policies 

that specifically apply to National Park Service minerals and geologic resources. The table does not 

include laws of general application (e.g., Endangered Species Act, Clean Water Act, Wilderness Act, 

National Environmental Policy Act, or National Historic Preservation Act). The table does include the 

NPS Organic Act when it serves as the main authority for protection of a particular resource or when 

other, more specific laws are not available. Information is current as of August 2015. Contact the NPS 

Geologic Resources Division for detailed guidance.

Resource Resource-specific Laws Resource-specific Regulations 2006 Management Policies Paleontology

National Parks Omnibus Management 

Act of 1998, 16 USC § 5937 protects the 

confidentiality of the nature and specific 

location of paleontological resources and 

objects.

Paleontological Resources Preservation 

Act of 2009, 16 USC § 470aaa et 

seq. provides for the management and 

protection of paleontological resources on 

federal lands.

36 CFR § 2.1(a)(1)(iii) prohibits destroying, 

injuring, defacing, removing, digging or 

disturbing paleontological specimens or 

parts thereof.

Prohibition in 36 CFR § 13.35 applies 

even in Alaska parks, where the surface 

collection of other geologic resources is 

permitted.

Regulations in association with 2009 PRPA 

are being finalized (August 2015).

Section 4.8.2 requires NPS to protect 

geologic features from adverse effects of 

human activity.

Section 4.8.2.1 emphasizes Inventory and 

Monitoring, encourages scientific research, 

directs parks to maintain confidentiality of 

paleontological information, and allows 

parks to buy fossils only in accordance with 

certain criteria.

Rocks and Minerals

NPS Organic Act, 16 USC § 1 et seq.

directs the NPS to conserve all resources 

in parks (including rock and mineral 

resources), unless otherwise authorized by 

law.

36 CFR § 2.1 prohibits possessing, 

destroying, disturbing mineral resources...

in park units.

Exception: 36 CFR § 13.35 allows some 

surface collection of rocks and minerals 

in some Alaska parks (not Klondike 

Gold Rush, Sitka, Denali, Glacier Bay, 

or Katmai) by non-disturbing methods 

(e.g., no pickaxes), which can be stopped 

by superintendent if collection causes 

significant adverse effects on park 

resources and visitor enjoyment.

Section 4.8.2 requires NPS to protect 

geologic features from adverse effects of 

human activity.

Park Use of Sand and Gravel

Materials Act of 1947, 30 USC § 601

does not authorize the NPS to dispose of 

mineral materials outside of park units.

None applicable.

Section 9.1.3.3 clarifies that only the 

NPS or its agent can extract park-owned 

common variety minerals (e.g., sand and 

gravel), and:

-only for park administrative uses;

-after compliance with NEPA and other 

federal, state, and local laws, and a 

finding of non-impairment;

-after finding the use is park’s most 

reasonable alternative based on 

environment and economics;

-parks should use existing pits and create 

new pits only in accordance with parkwide borrow management plan;

-spoil areas must comply with Part 6 

standards; and

-NPS must evaluate use of external 

quarries.

Any deviation from this policy requires a 

written waiver from the Secretary, Assistant 

Secretary, or Director.
56

Resource Resource-specific Laws Resource-specific Regulations 2006 Management Policies Upland and Fluvial Processes

Rivers and Harbors Appropriation 

Act of 1899, 33 USC § 403 prohibits the 

construction of any obstruction on the 

waters of the United States not authorized 

by congress or approved by the USACE.

Clean Water Act 33 USC § 1342 requires 

a permit from the USACE prior to any 

discharge of dredged or fill material 

into navigable waters (waters of the US 

[including streams]). 

Executive Order 11988 requires federal 

agencies to avoid adverse impacts to 

None applicable.

Section 4.1 requires NPS to manage 

natural resources to preserve fundamental 

physical and biological processes, as well 

as individual species, features, and plant 

and animal communities; maintain all 

components and processes of naturally 

evolving park ecosystems.

Section 4.1.5 directs the NPS to reestablish natural functions and processes 

in human-disturbed components of natural 

systems in parks, unless directed otherwise 

by Congress.

Section 4.4.2.4 directs the NPS to allow 

natural recovery of landscapes disturbed by 

natural phenomena, unless manipulation of 

the landscape is necessary to protect park 

development or human safety. 

Section 4.6.4 directs the NPS to (1) 

manage for the preservation of floodplain 

values; [and] (2) minimize potentially 

hazardous conditions associated with 

flooding.

floodplains. (see also D.O. 77-2)

Executive Order 11990 requires plans for 

potentially affected wetlands (including 

riparian wetlands). (see also D.O. 77-1)

Section 4.6.6 directs the NPS to manage 

watersheds as complete hydrologic systems 

and minimize human-caused disturbance 

to the natural upland processes that deliver 

water, sediment, and woody debris to 

streams.

Section 4.8.1 directs the NPS to allow 

natural geologic processes to proceed 

unimpeded. Geologic processes...include...

erosion and sedimentation...processes. 

Section 4.8.2 directs the NPS to protect 

geologic features from the unacceptable 

impacts of human activity while allowing 

natural processes to continue.

Caves and Karst Systems

Federal Cave Resources Protection Act 

of 1988, 16 USC §§ 4301 – 4309 requires 

Interior/Agriculture to identify “significant 

caves” on Federal lands, regulate/

restrict use of those caves as appropriate, 

and include significant caves in land 

management planning efforts. Imposes 

civil and criminal penalties for harming 

a cave or cave resources. Authorizes 

Secretaries to withhold information about 

specific location of a significant cave from 

a Freedom of Information Act (FOIA) 

requester. 

National Parks Omnibus Management 

Act of 1998, 16 USC § 5937 protects the 

confidentiality of the nature and specific 

location of cave and karst resources.

36 CFR § 2.1 prohibits possessing/ 

destroying/disturbing...cave resources...in 

park units.

43 CFR Part 37 states that all NPS caves 

are “significant” and sets forth procedures 

for determining/releasing confidential 

information about specific cave locations to 

a FOIA requester.

Section 4.8.1.2 requires NPS to maintain 

karst integrity, minimize impacts.

Section 4.8.2 requires NPS to protect 

geologic features from adverse effects of 

human activity.

Section 4.8.2.2 requires NPS to protect 

caves, allow new development in or on 

caves if it will not impact cave environment, 

and to remove existing developments if 

they impair caves.

Section 6.3.11.2 explains how to manage 

caves in/adjacent to wilderness.
57

Resource Resource-specific Laws Resource-specific Regulations 2006 Management Policies Mining Claims

Mining in the Parks Act of 1976, 16 

USC § 1901 et seq. authorizes NPS 

to regulate all activities resulting from 

exercise of mineral rights, on patented and 

unpatented mining claims in all areas of the 

System, in order to preserve and manage 

those areas.

General Mining Law of 1872, 30 USC 

§ 21 et seq. allows US citizens to locate 

mining claims on Federal lands. Imposes 

administrative and economic validity 

requirements for “unpatented” claims (the 

right to extract Federally-owned locatable 

minerals). Imposes additional requirements 

for the processing of “patenting” claims 

(claimant owns surface and subsurface). 

Use of patented mining claims may be 

limited in Wild and Scenic Rivers and 

OLYM, GLBA, CORO, ORPI, and DEVA. 

Surface Uses Resources Act of 1955, 

30 USC § 612 restricts surface use of 

unpatented mining claims to mineral 

activities.

36 CFR § 5.14 prohibits prospecting, 

mining, and the location of mining claims 

under the general mining laws in park 

areas except as authorized by law.

36 CFR Part 6 regulates solid waste 

disposal sites in park units.

36 CFR Part 9, Subpart A requires the 

owners/operators of mining claims to 

demonstrate bona fide title to mining 

claim; submit a plan of operations to 

NPS describing where, when, and how; 

prepare/submit a reclamation plan; and 

submit a bond to cover reclamation and 

potential liability.

Section 6.4.9 requires NPS to seek to 

remove or extinguish valid mining claims in 

wilderness through authorized processes, 

including purchasing valid rights. Where 

rights are left outstanding, NPS policy is 

to manage mineral-related activities in 

NPS wilderness in accordance with the 

regulations at 36 CFR Parts 6 and 9A.

Section 8.7.1 prohibits location of new 

mining claims in parks; requires validity 

examination prior to operations on 

unpatented claims; and confines operations 

to claim boundaries.

36 CFR Part 6 regulates solid waste 

disposal sites in park units.

Nonfederal Oil and Gas

NPS Organic Act, 16 USC § 1 et seq.

authorizes the NPS to promulgate 

regulations to protect park resources and 

values (from, for example, the exercise of 

mining and mineral rights).

36 CFR Part 9, Subpart B requires the 

owners/operators of nonfederally owned 

oil and gas rights to

-demonstrate bona fide title to mineral 

rights;

-submit a plan of operations to NPS 

describing where, when, how they intend 

to conduct operations;

-prepare/submit a reclamation plan; and 

-submit a bond to cover reclamation and 

potential liability.

Section 8.7.3 requires operators to comply 

with 9B regulations.

Nonfederal minerals other than oil and gas

NPS Organic Act, 16 USC §§ 1 and 3

Surface Mining Control and 

Reclamation Act of 1977, 30 USC § 

1201 et. seq. prohibits surface coal 

mining operations on any lands within the 

boundaries of a NPS unit, subject to valid 

existing rights.

NPS regulations at 36 CFR Parts 1, 5, 

and 6 require the owners/operators of 

other types of mineral rights to obtain 

a special use permit from the NPS as a 

§ 5.3 business operation, and § 5.7 – 

Construction of buildings or other facilities, 

and to comply with the solid waste 

regulations at Part 6.

SMCRA Regulations at 30 CFR Chapter 

VII govern surface mining operations on 

Federal lands and Indian lands by requiring 

permits, bonding, insurance, reclamation 

, and employee protection. Part 7 of the 

regulations states that National Park System 

lands are unsuitable for surface mining.

Section 8.7.3 states that operators 

exercising rights in a park unit must comply 

with 36 CFR Parts 1 and 5.
58

Resource Resource-specific Laws Resource-specific Regulations 2006 Management Policies Geothermal

Geothermal Steam Act of 1970, 30 USC 

§ 1001 et seq. as amended in 1988, 

states that

-no geothermal leasing is allowed in parks;

-“significant” thermal features exist in 16 

park units (features listed by the NPS at 52 

Fed. Reg. 28793-28800 [August 3, 1987], 

and thermal features in Crater Lake, Big 

Bend, and Lake Mead);

-NPS is required to monitor those features; 

and

-based on scientific evidence, Secretary 

of Interior must protect significant NPS 

thermal features from leasing effects.

Geothermal Steam Act Amendments 

of 1988, Public Law 100--443 prohibits 

geothermal leasing in the Island Park 

known geothermal resource area near 

Yellowstone and outside 16 designated 

NPS units if subsequent geothermal 

development would significantly adversely 

affect identified thermal features. 

None applicable

Section 4.8.2.3 requires NPS to

-preserve/maintain integrity of all thermal 

resources in parks.

-work closely with outside agencies, and

-monitor significant thermal features.

Soils

Soil and Water Resources Conservation 

Act, 16 USC §§ 2011–2009 provides for 

the collection and analysis of soil and 

related resource data and the appraisal of 

the status, condition, and trends for these 

resources.

Farmland Protection Policy Act, 7 USC 

§ 4201 et. seq. requires NPS to identify 

and take into account the adverse effects 

of Federal programs on the preservation 

of farmland; consider alternative actions, 

and assure that such Federal programs 

are compatible with State, unit of local 

government, and private programs 

and policies to protect farmland. NPS 

actions are subject to the FPPA if they 

may irreversibly convert farmland (directly 

or indirectly) to nonagricultural use and 

are completed by a Federal agency or 

with assistance from a Federal agency. 

Applicable projects require coordination 

with the Department of Agriculture’s 

Natural Resources Conservation Service 

(NRCS).

7 CFR Parts 610 and 611 are the US 

Department of Agriculture regulations 

for the Natural Resources Conservation 

Service. Part 610 governs the NRCS 

technical assistance program, soil erosion 

predictions, and the conservation of private 

grazing land. Part 611 governs soil surveys 

and cartographic operations. The NRCS 

works with the NPS through cooperative 

arrangements.

Section 4.8.2.4 requires NPS to

-prevent unnatural erosion, removal, and 

contamination;

-conduct soil surveys;

-minimize unavoidable excavation; and

-develop/follow written prescriptions 

(instructions).
The Department of the Interior protects and manages the nation’s natural resources and cultural heritage; provides scientific and 

other information about those resources; and honors its special responsibilities to American Indians, Alaska Natives, and affiliated 

Island Communities.

NPS 125/129746, September 2015
National Park Service

U.S. Department of the Interior

Natural Resource Stewardship and Science 

1201 Oak Ridge Drive, Suite 150 

Fort Collins, Colorado 80525

www.nature.nps.gov

EXPERIENCE YOUR AMERICATM


Map Unit Properties Table: Capulin Volcano National Monument, Page 1 of 2 

Map Unit Properties Table: Capulin Volcano National Monument

Colors correspond to the lava flow series map. Bold text refers to sections in the report. Baby Capulin and Mud Hill lava flow series are not mapped within Capulin Volcano National Monument.

Age Lava Flow Series Geologic Features and Processes Geologic Resource Management Issues Geologic History QUATERNARY (Pleistocene)

Baby Capulin

Volcanic Rocks and Volcanoes—Baby Capulin is a cinder cone composed of Capulin Basalt (dark, fluid lava, containing 50%–55% 

silica). 

Raton-Clayton Volcanic Field—the vent at Baby Capulin is one of an estimated 125 vents in the Raton-Clayton volcanic field. Baby 

Capulin erupted during the Capulin phase (1.69 million–32,000 years ago) in the central part of the volcanic field.

Volcanic Features—Baby Capulin is composed of basaltic lava and includes a vent (point feature in the GRI GIS data set). 

View from Capulin Volcano—prominent feature of the viewshed of Capulin Volcano National Monument, northeast of Capulin 

Volcano. 

None reported.

Capulin Phase—third youngest eruption in the 

Raton-Clayton volcanic field, 36,000 ± 4,000 

years ago. 

Fourth Series

Volcanic Rocks and Volcanoes—Fourth Series lava flows are composed of Capulin Basalt (dark, fluid lava, containing 50%–55% 

silica).

Raton-Clayton Volcanic Field—Fourth Series lava flows erupted during the Capulin phase in the central part of the volcanic field.

Volcanic Features—Fourth Series lava flows occur at the northeastern corner of Capulin Volcano National Monument. No volcanic 

features in this series were mapped by Richman (2010).

Aeolian Features—vesicles, cavities, and cracks in lava flows filled with loess, which plays a role in soil formation.

Paleontological Resources—no fossils documented within Capulin Volcano National Monument, to date. Potential for tree molds on 

lava flows, and pack rat middens in larger cavities of flows. .

Erosion and Cinder Mining—erosion as a result of 

cinder mining activities occurs in Fourth Series lava flows.

Capulin Phase (Boca Eruption)—Fourth Series 

lava extruded from a vent in the boca and flowed 

northward, then eastward between Capulin 

Volcano and Mud Hill. The Capulin Volcano 

eruption then ceased.

Third Series

Volcanic Rocks and Volcanoes—Third Series lava flows are composed of Capulin Basalt (dark, fluid lava, containing 50%–55% 

silica).

Raton-Clayton Volcanic Field—Third Series lava flows erupted during the Capulin phase in the central part of the volcanic field.

Volcanic Features—Third Series lava flows contain lava, lava ridges, levees, squeeze-ups, and tumuli. 

View from Capulin Volcano—lava of this series covers the area between Capulin Volcano and the town of Capulin, New Mexico.

Aeolian Features—vesicles, cavities, and cracks in lava flows filled with loess, which plays a role in soil formation.

Paleontological Resources—no fossils documented within Capulin Volcano National Monument, to date. Potential for tree molds on 

lava flows, and pack rat middens in larger cavities of flows.

Volcano Road—traverses Third Series lava flows.

Capulin Phase (Boca Eruption)—Third Series 

lava extruded from a vent in the boca and flowed 

to the south and west.

Second Series

Volcanic Rocks and Volcanoes—Second Series lava flows composed of Capulin Basalt (dark, fluid lava, containing 50%–55% 

silica).

Raton-Clayton Volcanic Field—Second Series lava flows erupted during the Capulin phase in the central part of the volcanic field.

Volcanic Features—Second Series lava flows contain levees, squeeze-ups, and tumuli. 

View from Capulin Volcano—prominent pressure ridges are visible on these lava flows.

Aeolian Features—vesicles, cavities, and cracks in lava flows filled with loess, which plays a role in soil formation.

Paleontological Resources—no fossils documented within Capulin Volcano National Monument, to date. Potential for tree molds on 

lava flows, and pack rat middens in larger cavities of flows.

Volcano Road—traverses Second Series lava flows.

Erosion—areas of erosion along the Lava Flow Trail.

Capulin Phase (Boca Eruption)—Second Series 

lava flows extruded from a vent in the boca and 

flowed to the south and southeast.
Colors correspond to the lava flow series map. Bold text refers to sections in the report. Baby Capulin and Mud Hill lava flow series are not mapped within Capulin Volcano National Monument.

Map Unit Properties Table: Capulin Volcano National Monument, Page 2 of 2 

Age Lava Flow Series Geologic Features and Processes Geologic Resource Management Issues Geologic History

Volcanic Rocks and Volcanoes—boca is composed of Capulin Basalt (dark, fluid lava, containing 50%–55% silica). Boca is on the 

western side of the main cinder cone.

Boca

Raton-Clayton Volcanic Field—boca contains two of an estimated 125 vents in the volcanic field. Boca erupted during the Capulin 

phase concentrated in the central part of the volcanic field.

Capulin Volcano—because activity shifted to vents in the boca, Capulin Volcano was never breached, and its classic shape was 

preserved. 

Volcanic Features—boca contains vents, boca ramparts, levees, lava lakes, push-ups, rafted cinder cones, spatter deposits, 

spatter flows, lava cascades, lava ridges, squeeze-ups, and tumuli. 

Cave Management—boca contains cave features and 

collapsed lava tubes; a cave inventory and appropriate 

management plan of these features are needed.

Geothermal Systems and Hydrothermal Features—

possible “hot vent” near the maintenance building needs 

to be identified and documented.

Capulin Phase (Boca Eruption)—after eruption 

of the main cinder cone ceased, lava erupted out 

of the boca.

View from Capulin Volcano—boca is visible below the parking area at the summit.

QUATERNARY 

(Pleistocene)

Paleontological Resources—no fossils documented within Capulin Volcano National Monument, to date. Potential for tree molds on 

lava flows, and pack rat middens in larger cavities of flows.

Main Cone

Volcanic Rocks and Volcanoes—main cone is composed of Capulin Basalt (dark, fluid lava, containing 50%–55% silica). Capulin 

Volcano is a textbook example of a cinder cone.

Raton-Clayton Volcanic Field—Capulin Volcano contains one of an estimated 125 vents in the volcanic field. The volcano erupted 

during the Capulin phase concentrated in the central part of the field.

Capulin Volcano—archetypal cinder cone. 

Volcanic Features—main cone contains a vent. 

Age of Capulin Volcano—once considered less than 10,000 years old but now known to be 55,000 ± 2,000 years old.

View from Capulin Volcano—dramatic view of the Raton-Clayton volcanic field; 360° panorama along Crater Rim Trail of four 

states (New Mexico, Colorado, Oklahoma, and Texas) on clear days.

Aeolian Features—the asymmetry of the crater rim, which is higher on the northeastern side, is an outcome of prevailing-wind 

direction during the eruption.

Volcano Road—spirals around Capulin Volcano, and is 

the greatest impact to the geologic resources at Capulin 

Volcano National Monument.

Erosion—arguably the most significant threat to the 

geologic resources, particularly the cinder cone, at the 

monument. 

Slope Movements—ongoing processes (e.g., rockfalls, 

cinder slides, debris flows, and slope failures); particular 

concern where they impact infrastructure, primarily

Volcano Road. 

Volcano Hazards and Risk—a future eruption in the 

Raton-Clayton volcanic field will likely create a new cinder 

cone, rather than erupting from an existing one. In 

addition to cone formation, other hazards include effusive 

lava flows, localized ash fall, earthquakes (as magma rises 

and causes shaking), volcanic gases, volcanic projectiles 

such as bombs, and wildfires.

Capulin Phase (Cone Building Eruption)—

fissure or series of small vents coalesced into one 

main vent, building up Capulin Volcano. The 

cinder-cone eruption lasted for a period of weeks 

to years 55,000 ± 2,000 years ago.

Volcanic Rocks and Volcanoes—First Series lava flows are composed of Capulin Basalt (dark, fluid lava, containing 50%–55% 

silica).

First Series

Raton-Clayton Volcanic Field—First Series lava flows contain one of an estimated 125 vents in the volcanic field. Lava flows are part 

of the Capulin phase concentrated in the central part of the field.

Volcanic Features—First Series lava flows contain a vent and a pooled lava flow. 

Aeolian Features—vesicles, cavities, and cracks in lava flows filled with loess, which plays a role in soil formation.

None reported.

Capulin Phase (First Series Lava Flows)—

emplaced early in the Capulin Volcano eruption; 

eruption of First Series lava is contemporaneous 

with cone building. Lava flowed eastward from 

fissure or series of small vents.

Paleontological Resources—no fossils documented within Capulin Volcano National Monument, to date. Potential for tree molds on 

lava flows, and pack rat middens in larger cavities of flows.

Volcanic Rocks and Volcanoes—composed of Capulin Basalt (dark, fluid lava, containing 50%–55% silica). Mud Hill formed 

during a phreatomagmatic eruption (driven by the interaction of magma and water) followed by eruption of basalt flows, which 

breached the side of the volcano.

Mud Hill

Raton-Clayton Volcanic Field—Mud Hill contains two of an estimated 125 vents in the volcanic field. The volcano is part of the 

Capulin phase concentrated in the central part of the field. None reported.

Capulin Phase—erupted 1,690,000 ± 30,000 

years ago. Notably older than surrounding 

volcanoes. 

Volcanic Features—vents. 

View from Capulin Volcano—Mud Hill is a prominent feature in the viewshed of Capulin Volcano National Monument, northeast 

Capulin Volcano. 

of