Geological Society of America Fall 2003 Meeting, Seattle, Washington
Session No. 172 Quaternary Geology/Geomorphology III: Glaciers, Volcanoes, Caves, and
Isotopes
Cinder Cone Morphometry and Volume Distribution at Newberry Volcano, Oregon:
Implications for Age Relations and Structural Control on Eruptive Process
Stephen B. Taylor, Jeffrey H. Templeton, Denise E.L. Giles, Earth and Physical Sciences
Department, Western Oregon University, Monmouth, Oregon 97361, email: taylors@wou.edu
1. ABSTRACT
Newberry Volcano of central Oregon covers greater than 1300 km2 and is associated
with over 400 basaltic cinder cones and fissure vents (Holocene-Late Pleistocene). Digital
geologic maps and 10-m USGS DEMs were compiled with 182 single cones selected for
morphometric and volume analyses using GIS. This robust data set provides a framework from
which to evaluate cone volume distributions and relative ages in the context of erosional
degradation models.
Based on visual inspection of DEM-derived shaded relief maps, each cone was
qualitatively ranked with a morphology classification ranging from 1 (well defined cone-crater
morphology) to 7 (very poorly defined cone-crater morphology). Morphometric measurements
include cone height (Hc), average cone slope (Sc), long-axis diameter (Dl), short axis diameter
(Ds), and height:width ratio (Hc/Wc where Wc=(Dl+Ds)/2). Individual cone DEMs were
extracted and volumes (Vc) calculated using a kriging-based algorithm. Average slopes were
derived from 10-m elevation nodes contained within cone polygons. Results according to
qualitative morphology rank are summarized as follows: (A) Frequency (no.) 1=11, 2=21, 3=10,
4=35, 5=11, 6=35, 7=59; (B) Average Vc (m3) 1=1.46 x 107, 2=1.53 x 107, 3=1.25 x 107,
4=4.88 x 106, 5=4.65 x 106, 6=3.07 x 106, 7=1.10 x 106; (C) Average Sc (deg) 1=19.9, 2=18.2,
3=18.1, 4=14.9, 5=14.4, 6=11.9, 7=10.2; (D) Average Hc (m) 1=132, 2=124, 3=126, 4=76,
5=78, 6=59, 7=50; (E) Average Hc/Wc 1=0.18, 2=0.20, 3=0.19, 4=0.15, 5=0.14, 6=0.13, 7=0.13.
Existing cone degradation models demonstrate that with increasing cone age, Sc, Hc, and Hc/Wc
decrease, respectively. Systematic t-tests (a=0.05) of these parameters between morphology
classes statistically separates cones into two groups: (1) ”Morphometric Group I” = ranks 1-3,
and (2) ”Morphometric Group II” = ranks 4-7. Spatial analysis of cone-volume distributions
shows maxima oriented NW-SE, parallel to regional fault trends (Tumalo Fault and Northwest
Rift zones).
The above results suggest that there are two distinct age populations of cinder cones at
Newberry. Parallel alignment of cone-volume maxima with known fault trends implies that
these structures have an important control on eruptive process in the region. This study provides
a framework to guide future geomorphic analysis and radiometric age dating of cinder cones at
Newberry Volcano.
2. INTRODUCTION
Newberry Volcano is located in central Oregon, in close proximity to the cities of Bend
and LaPine (Figure 1). With an estimated volume of 450 km3, Newberry is one of the largest
volcanoes in the contiguous United States. It is an elongated shield that extends 60 km long
north south and 30 km wide east west; the summit is marked by a caldera that is 7 by 5 km
1
across (Figures 2 and 3) (MacLeod and Sherrod, 1988). This broad shield complex covers greater
than 1600 km2 and is associated with over 400 basaltic cinder cones and fissure vents
(Holocene-Late Pleistocene; Jensen 2002) (Figure 2). The large number of cinder cones
provides an important geologic framework from which to conduct morphometric analyses, test
existing erosional degradation models, and decipher controls on eruptive magnitude and
frequency.
This work represents preliminary morphometric and volume analyses of 182 single
cinder cones distributed across Newberry Volcano. Data were compiled from digital geologic
maps and 10-m DEMs using GIS (Giles and others, 2003). The results are placed in the context
of relative age dating and structural control on volcanic process. As population density is rapidly
increasing in Bend and surrounding areas (annual avg. growth = 21%; U.S. Census Bureau,
2003), results of this ongoing investigation may have important implications for volcanic hazards
assessment (after Sherrod et al., 1997).
3. GEOLOGIC SETTING
Newberry Volcano lies at the west end of the High Lava Plains about 65 km east of the
Cascade Range (Figure 1). Owing to its location, Newberry displays tectonic and compositional
characteristics of the Cascade Range, High Lava Plains, and Basin and Range (MacLeod and
others, 1981; MacLeod and Sherrod. 1988). The volcano is also positioned at the younger end of
a sequence of rhyolite domes and caldera-forming ash-flow tuffs that decrease in age from 10
m.y. in southeastern Oregon to less than 1 m.y. near the caldera (Figure 1).
Newberry is located in a complex, extensional tectonic setting dominated by Pliocene to
Quaternary faults (MacLeod and others, 1981; MacLeod and Sherrod. 1988). . Several major
fault zones surround and converge near Newberry, including the Brothers fault zone, the Tumalo
fault zone, and the Walker Rim fault zone (Figures 1 and 2). The Brothers fault zone is a major
west-northwest trending domain of dominantly right-lateral strike slip faults that extend from
southeastern Oregon to the northeast flank of Newberry, where the faults are buried by
Quaternary lava flows (MacLeod and others, 1981; MacLeod and Sherrod. 1988). The northnorthwest trending Tumalo fault zone extends from the east side of the Cascades to the lower
northern flanks of Newberry, where older lava flows are offset by
this fault system. Along the southern flanks of Newberry, the north-northeast trending Walker
Rim fault zone offsets older flows (Figures 1 and 2).
The flanks of Newberry Volcano are covered mostly by basaltic andesite lava flows with
subordinate amounts of basalt and andesite lavas (Figure 2). Flow rocks are typically porphyritic
with abundant plagioclase phenocrysts and lesser amounts of olivine that resembles basalt, but
most are basaltic andesite with SiO2 values of 54-55 wt.% and compositional characteristics
similar to calc-alkaline flows in Cascade Range (MacLeod and Sherrod. 1988). Holocene flow
rocks are subdivided relative to the Mazama ash-fall deposits into younger than 6,850 and older
than 6,850 (MacLeod and others, 1981). The Mazama pumice deposit, which mantles the area
around Newberry with up 1 m of ash and lapilli, was erupted from Mt. Mazama to form Crater
Lake ~6800 years ago (6845+/-50 C14 yr B.P; Bacon, 1983).
Cinder cones and related lava flows are most abundant on the north and south flanks of
Newberry, less common on the east flank, and uncommon on the west flank (Figures 2 and 3).
Many cones are aligned, and previous workers have identified three broad zones based on these
arrays (MacLeod and others, 1981; MacLeod and Sherrod. 1988). On the south flank, the cones
display a conspicuous north-northeast trend, co-linear with the Walker Rim fault zone (Figure 2).
On the north flank, the cones form a wider north-northwest trending array that parallels the
2
Tumalo fault zone. Some on the north flank also display curved arrangements parallel to caldera
walls and are presumably related to local stresses within volcano (MacLeod and Sherrod. 1988)
(Figure 2). MacLeod and Sherrod (1988) interpreted the cone and vent alignments to represent
the surface expression of dikes at depth that formed in response to regional stress fields. They
observed that the apparent curvilinear distribution of cinder cones and fissure vents on the north
and south flanks of Newberry trend mostly parallel to the Walker Rim and Tumalo fault zones,
suggesting that these fault zones form a single arc-shaped fault zone beneath Newberry.
MacLeod and Sherrod (1988) also suggested that north-northwest trending cones and fissure
vents are relatively younger than those trending north-northeast. The work presented herein
provides a quantitative framework from which to evaluate this interpretation.
4. METHODOLOGY
A select set of Newberry cinder cones (n = 182) were analyzed by measuring a suite of
morphometric parameters that are commonly used to quantitatively characterize shape, eruptive
volume, and relative age. Data sources included a digitized version of the published Newberry
geologic map (1:62,500; MacLeod and others, 1995; Giles and others, 2003), USGS 10-m digital
elevation models (DEM), and 1:24000 digital orthophotoquads (DOQ). The sample population
was selected on the basis of the following criteria: (1) basaltic cinder cones mapped as "Qc" by
MacLeod and others (1995), (2) single cones that are not part of a fissure-vent system, (3) intact
cones that do not appear to be topographically breached, (4) exposed cones that are not
significantly covered by younger lava flows, and (5) cones that are clearly separated from nearest
neighbors (e.g. Lava Butte, Figure 3B).
Individual cone DEMs were extracted from the USGS 10-m quadrangles and analyzed
using a suite of GIS-related software including ArcView (ESRI), ArcGIS (ESRI), Idrisi (Clark
Labs), Cartalynx (Clark Labs), and Surfer (Golden Software). Based on visual inspection of
DEM-derived shaded relief maps, each cone was qualitatively ranked with a morphology
classification ranging from 1 (well defined cone-crater morphology) to 7 (very poorly defined
cone-crater morphology) (Table 1, Figure 4). Morphometric techniques were modified from
those developed by Scott and Trask (1971), Porter (1972), and Wood (1980). Parameters include
cone height (Hc), average cone slope (Sc), long-axis diameter (Dl), short axis diameter (Ds), and
height:width ratio (Hc/Wc where Wc=(Dl+Ds)/2). Long and short axes (Dl and Ds,
respectively) were digitized from cone polygon outlines as defined by unit Qc from MacLeod
and others (1995). Cone height and slope were derived from 10-m elevation nodes contained
within Qc polygons. Finally, cone volumes were calculated from the DEMs by clipping the
edifice footprint (2x the cone-bounding rectangle), masking the cone relief to zero, and regridding the "masked" cone using a kriging-based algorithm (Figure 5). Cone volumes (Vc)
were derived by subtracting the masked cone DEM (Figure 5B) from the original footprint
(Figure 5A). Systematic t-test analyses (a = 0.05) were subsequently used to conduct means
comparisons between cone morphology rating classes.
5. RESULTS
5A. Morphometric Data
Figure 6 is a location map showing the selected Newberry cinder cones and their
respective morphology ratings as described above. Morphometric results for each of the seven
morphology-rating classes are listed in Table 2 and displayed in Figure 7. The results for each
3
class are summarized as follows: (A) Frequency (no.) 1=11, 2=21, 3=10, 4=35, 5=11, 6=35,
7=59; (B) Average Vc (m3) 1=1.46 x 107, 2=1.53 x 107, 3=1.25 x 107, 4=4.88 x 106, 5=4.65 x
106, 6=3.07 x 106, 7=1.10 x 106; (C) Average Sc (deg) 1=19.9, 2=18.2, 3=18.1, 4=14.9, 5=14.4,
6=11.9, 7=10.2; (D) Average Hc (m) 1=132, 2=124, 3=126, 4=76, 5=78, 6=59, 7=50; (E)
Average Hc/Wc 1=0.18, 2=0.20, 3=0.19, 4=0.15, 5=0.14, 6=0.13, 7=0.13.
5B. T-Test Results
Results of systematic t-tests (a=0.05) between morphology rating categories are listed in
Table 3. Mean cone slope (Sc), cone height (Hc) and height:width ratios (Hc/Wc) were
compared to identify morphometric similarities or differences between rating categories.
Systematic t-tests statistically separated cone rating categories into two groups: (1)
”Morphometric Group I” = ranks 1-3, and (2) ”Morphometric Group II” = ranks 4-7 (Table 3,
Figure 7).
5C. Cone Volume Analysis
Results of cone volume calculations are summarized in Table 4. Cone volumes range
from 1.97x103 m3 to 4.53x107 m3, with an average of 5.62x106 m3. Volume data were also
contoured to show spatial distribution with respect to regional structure (Figure 8). Cones with
the highest volumes occur on the north flank of Newberry. Volume maxima both north and
south of the summit caldera are broadly co-linear with the north-northwest trending Tumalo fault
zone.
6. DISCUSSION
Existing cone degradation models demonstrate that as cone age increases, Sc, Hc, and
Hc/Wc decrease, respectively (e.g. Scott and Trask, 1971; Dowrenwend and others, 1986;
Hooper and Sheridan, 1998). Cones degrade over time by both diffusive and advective erosion
processes, with mass transfer from hillslope to debris apron and filling of the central crater
(Dohrenwend and others, 1986; Blauvett, 1998; Rech and others, 2001). The net result is
reduction of cone height and slope through time coupled with the loss of crater definition.
GIS-based analyses presented in this paper indicate that there are are two distinct
populations of cinder cones at Newberry. Based on comparison with similar studies, these data
suggest that cones included in Morphometric Group I are relatively “young” compared to those
in Group II, which are relatively “old”. As such, Group I Sc and Hc/Wc values average 19-20o
and 0.19, respectively, while Group II values average 11-15o and 0.14. By comparing Newberry
data with age-calibrated cone morphometry studies in Arizona (Hooper and Sheridan, 1998), the
results imply that both Group I and Group II cones fall within a “Holocene-Latest Pleistocene”
age category. However, higher resolution chronometry is required to more definitively establish
age trends in the cones selected for this study. Based on preliminary comparison with dated
eruptive events at Newberry (Jensen, 2000), it is uncertain if the morphometric groupings
delineated in this study are a function of age differences (i.e. degradational processes) or a
combination of other variables such as climate, post-eruption cone burial, lava composition, and
episodic (“polygenetic”) eruption cycles. Further radiometric and geomorphic dating studies will
be required to definitively decipher the factors controlling the two morphometric groupings
identified in this work.
4
Cone clustering and alignment patterns are commonly recognized at volcanic fields
(Porter, 1972; Settle, 1979; Connor, 1990). Spatial-distribution patterns of Newberry
morphometric groups (Figure 9) shows a northwest-southeast alignment of Group I cones and a
northeast-southwest alignment of some Group II cones. While care must be taken when
inferrring linear trends from cinder cone arrays, these data lend support to the hypothesis of
MacLeod and Sherrod (1988) that north-northwest trending clusters are relatively younger than
those oriented north-northeast. Regional and local tectonic stress fields are often interpreted as
the primary factor controlling such cone distribution patterns. Parallel alignment of Newberry
cone-volume maxima with the Tumalo fault zone implies that this structure has an important
control on eruptive process. This observation supports the contention of MacLeod and Sherrod
(1998) that faulting and regional tectonic stress fields structurally control mafic eruptions at
Newberry.
7. CONCLUSION
Morphometric and volume-distribution analyses of cinder cones at Newberry Volcano
suggest that cones are systematically organized in both space and time. Two morphometric
groupings of cinder cones are statistically recognized at the 95% confidence level. Possible
controlling factors include degradation processes, age differences, climate, post-eruption cone
burial, lava composition, and episodic (polygenetic) eruption cycles. Parallel alignment of conevolume maxima with known fault trends implies that these structures have an important control
on eruptive processes in the region. This study provides a preliminary framework to guide future
geomorphic analyses and radiometric age dating of Newberry cinder cones.
8. ACKNOWLEDGMENTS
Work on this project was initially stimulated by group discussions related to the Fall 2000
Friends of the Pleistocene, Pacific Northwest Cell, field trip to Newberry Volcano. Special
thanks are extended to the FOP organizers and presenters for elucidating many of the interesting
research problems associated with Newberry. Portions of this study were funded by the College
of Liberal Arts and Sciences, the Faculty Development Grant Program, the ASWOU Student
Technology Fee Committee, and the PT3 Project at Western Oregon University. Tony Faletti,
Diane Horvath, Diane Hale, and Ryan Adams are also acknowledged as exemplary WOU Earth
Science students who assisted with the tedious task of map digitization.
9. REFERENCES CITED
Bacon, C.R., 1983, Eruptive history of Mount Mazama, Cascade Range, U.S.A.: Journal of
Volcanology and Geothermal Research, v. 18, p. 57-115.
Blauvett, D.J., 1998, Examples of scoria cone degradation in the San Francisco volcanic field,
Arizona: M.S. Thesis, State University of New York at Buffalo, Amherst, NY, 127 p.
Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.A., and Chitwood,
L.A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the Friends of the
Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
5
Connor, C.B., 1990, Cinder cone clustering in the TransMexican Volcanic Belt: Implications for
structural and petrologic models: Journal of Geophysical Research, v. 95, p. 19,395-19,405.
Dohrenwend, J.C., Wells, S.G., and Turrin, B.D., 1986, Degradation of Quaternary cinder cones
in the Cima volcanic field, Mojave Desert, California: Geological Society of America Bulletin,
v.97, p. 421-427.
Giles, D.E.L., Taylor, S.B., and Templeton, J.H., 2003, Compilation of a digital geologic map
and spatial database for Newberry volcano, central Oregon: A framework for comparative
analysis: Geological Society of America Abstracts with Programs, v. 35, no. 6, p. 189.
Higgins, MW., 1973, Petrology of Newberry Volcano, Central Oregon: Geological Society of
America Bulletin, v. 84, p. 455-488.
Hooper, D.M., and Sheridan, M.F., 1998, Computer-simulation models of scoria cone
degradation: Journal of Volcanology and Geothermal Research, v. 83, p. 241-267.
Jensen, R.A., 2000, Roadside Guide to the Geology of Newberry Volcano, 3rd ed.:
CenOreGeoPub, Bend, Oregon, 168 pp.
Jensen, R.A., and Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.
A., and Chitwood, L. A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the
Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
MacLeod, N. S., and Sherrod, D. R., 1988, Geologic evidence for a magma chamber beneath
Newberry Volcano, Oregon: Journal of Geophysical Research, v. 93, p. 10,067-10,079.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and McKee, E.H., 1981, Newberry Volcano,
Oregon, in Johnston, D. A., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in
Washington, Idaho, and northern California: U.S. Geological Survey Circular 838, p. 85-103.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and Jensen, R.A., 1995, Geologic Map of
Newberry Volcano, Deschutes, Klamath, and Lake Counties, Oregon: U.S. Geological Survey
Miscellaneous Geologic Investigations Map I-2455, scales 1:62,500 and 1:24,000.
Porter, S.C., 1972, Distribution, morphology, and size frequency of cinder cones on Mauna Kea
volcano, Hawaii: Geological Society of America Bulletin, v. 83, p. 3607-3612.
Rech, J.A., Reeves, R.W., and Hendricks, D.M., 2001, The influence of slope aspect on soil
weathering processes in the Springerville volcanic field, Arizona: Catena, v. 43, p. 49-62.
Scott, D.H., and Trask, N.J., 1971, Geology of the Lunar Crater volcanic field, Nye County, NV:
U.S. Geological Survey Professional Paper, 599-I, 22 p.
Settle, M., 1979, The structure and emplacement of cinder cone fields: American Journal of
Science, v. 279, p. 1089-1107.
6
Sherrod, D.R., Mastin, L.G., Scott, W.E., and Schilling, S.P., 1997, Volcano hazards at
Newberry Volcano, Oregon: U. S. Geological Survey, Open-file Report 97-513, 14 pp.
U.S. Census Bureau, 2003, Census data for the state of Oregon: online resource,
http://www.census.gov.
Walker, G.W., and MacLeod, N.S., 1991, Geologic Map of Oregon: U.S. Geological Survey,
Scale, 1:500,000.
Wood, C.A., 1980, Morphometric evolution of cinder cones: Journal of Volcanology and
Geothermal Research, v. 7, p. 387-413.
FIGURE / TABLE CAPTIONS
Figure 1. Generalized map of Oregon emphasizing the regional geologic and tectonic framework
of Newberry Volcano. Geology after Walker and MacLeod (1991).
Figure 2. Generalized geologic map of Newberry Volcano (after Jensen, 2000).
Figure 3A. Profile view of Newberry Volcano showing central caldera region and related cindercone field in foreground (red outlines).
3B. Aerial view of Lava Butte cinder cone (6160 +/- 70 C14 yrs) (Sept. 3, 1986, ©R.A. Jensen).
Figure 4. 10-m DEM relief maps for three select cinder cones at Newberry Volcano (map unit
“Qc” of MacLeod and others, 1995). Shaded relief maps were used to visually rank each cone in
the data set according to qualitative appearance of shape, slope configuration, and vent
morphologies (Table 1). Representative examples include Lava Butte (morphology rating = 1),
Pumice Butte (morphology rating = 4), and Hunter Butte (morphology rating = 7) (Refer to
Figure 6 for cone locations.)
Figure 5. Shaded-relief maps illustrating the kriging-based method by which cone volumes were
calculated from 10-m DEMs. Cone volumes were calculated by subtracting elevation surface B
from elevation surface A above. See text for discussion.
Figure 6. Map of Newberry Volcano showing outlines of single cinder cones selected for this
study (n = 182). Cone outlines were digitized from map polygon “Qc” of MacLeod and others
(1995). The cone morphology rating was derived from qualitative ranking of shapes, slope
configuration, and vent morphology as depicted on 10-m shaded relief maps. Inset shows
morphology frequency.
Figure 7A. Whisker plot of average cone slope (degrees) vs. qualitative cone morphology rating.
Morphometric groupings are based on systematic t-test results at the 95% confidence level as
summarized in Table 3.
Figure 7B. Whisker plot of cone height (meters) vs. qualitative cone morphology rating.
Morphometric groupings are based on systematic t-test results at the 95% confidence level as
summarized in Table 3.
7
Figure 7C. Whisker plot of cone height:width ratio vs. qualitative cone morphology rating.
Morphometric groupings are based on systematic t-test results at the 95% confidence level as
summarized in Table 3.
Figure 8. Contour map of select cinder cone volumes at Newberry Volcano. Note maxima
oriented NW-SE, parallel to regional trend of the Tumalo fault zone.
Figure 9. Map showing distribution of singles cones subdivided into the two cone populations
based on morphology rating. Group 1 cones consist of morphology rating classes 1, 2, and 3,
and Group 2 cones consist of morphology rating classes 4, 5, 6, and 7.
Table 1. Explanation of Qualitative Cone Morphology Rating
Table 2. Summary of Relevant Cone Morphometry Data.
Table 3. Results of Systematic T-Test Analyses.
Table 4. Results of Cone Volume Calcu-lations (m3).
8
Geological Society of America Fall 2005 Meeting, Salt Lake City, Utah
Session No. 190 Quaternary Geology and Geomorphology (Poster Booth 56)
Spatial Analysis of Cinder Cone Distribution at Newberry Volcano, Oregon: Implications for
Structural Control on Eruptive Process
Stephen B. Taylor, Jeffrey H. Templeton, Jeffrey Budnick, Chandra Drury, Jamie Fisher, and
Summer Runyan; Earth and Physical Sciences Department, Western Oregon University,
Monmouth, Oregon 97361, email: taylors@wou.edu
1. ABSTRACT
Newberry Volcano of central Oregon is located in a complex, extensional tectonic
setting. Fracture systems converging near the volcanic center include the Brothers (westnorthwest trending), Tumalo (north-northwest), and Walker Rim (northeast) fault zones.
Newberry covers greater than 1600 sq. km and is associated with over 400 basaltic cinder cones
and fissure vents (Holocene-Late Pleistocene). The large number of cinder cones provides a
robust data set from which to conduct spatial analyses of vent distribution patterns and
quantitatively test for structural controls on magma emplacement.
Newberry cone positions (n=296) were compiled from digital geologic maps and
statistically analyzed using GIS. Cone locations were further subdivided into northern (n=149)
and southern (n=147) domains to test for mutually independent relations between the three fault
zones. Observed cone patterns were tested for randomness and spatial anisotropy using a
combination of quadrat analysis (Komogorov-Simirnov test) and comparative-distribution
analysis via Monte Carlo simulations. The latter employed the “line-azimuth” and “pointdensity” techniques of Lutz (1986) and Zhang and Lutz (1989). Statistically significant conedistribution patterns were subsequently compared to fault trends to assess the degree to which
magma emplacement was guided by regional tectonic stress fields.
Results of the K-S tests reject the null hypothesis at the 95% confidence interval,
documenting that Newberry cinder cones are not randomly distributed. The Monte Carlo-based
analyses identify three significant cone alignments in the southern domain (dominant azimuth
directions = 0, 10-35, 340-350), and three in the northern (80, 280-295, 310). Combined data
from both domains strengthens the statistical significance of the 310 and 340-350 cone alignment
directions. Fault segment analysis reveals three dominant azimuthal trends in the region: 310320 (Brothers fault zone), 330-340 (Tumalo fault zone), and 45-55 (Walker Rim). The above
results suggest that the Brothers and Tumalo fault zones had a detectable control on cinder-cone
emplacement in both the northern and southern domains, whereas the Walker Rim is poorly
correlated to significant cone-alignment patterns. Cinder cone alignments with azimuthal trends
of 10-15, 30-35, and 85 suggest additional control by structural conditions other than those
represented by mapped surface faults.
2. INTRODUCTION
Cinder cones are point-like geologic features that provide a surface record of magmatic
emplacement processes through time. Numerous workers have observed that cinder cones
commonly occur in sets with notable clustered or aligned spatial patterns, rather than being
isotropically distributed (e.g. Carr, 1976; Hasenka and Carmichael, 1985; Wadge and Cross,
1988; Connor and Condit, 1989; Connor, 1990). Such cone alignments are often interpreted as
9
being the result of magma transport along pre-existing fracture zones or that they form in
relationship to regional stress fields at the time of crustal ascent (Kear, 1964; Nakamura, 1977;
Settle, 1979; Connor, 1987; Connor et al., 1992).
Newberry Volcano of central Oregon, is located in a complex, extensional tectonic
setting at the intersection of the Basin and Range, High Lava Plains, and Cascade Volcanic Arc
provinces (Figure 1). Several major fracture systems surround and converge near Newberry,
including the Brothers (west-northwest trending), Tumalo (north-northwest), and Walker Rim
(northeast) fault zones. With a volume of greater than 450 km3, Newberry is one of the largest
volcanoes in the contiguous United States and is associated with over 400 basaltic cinder cones
and fissure vents (Holocene-Late Pleistocene; Jensen 2002) (Figures 3 and 4). MacLeod and
Sherrod (1988) observed that the curvilinear distribution of cinder cones and fissure vents on the
flanks of Newberry trend mostly parallel to the Walker Rim and Tumalo fault zones, suggesting
that these structures may form a single arc-shaped fracture zone at depth and likely serve as
conduits that guide magma emplacement. While the structure-controlled, eruptive mechanism
posited by MacLeod and Sherrod (1988) has significant merit, supporting statistical analysis of
cone patterns and regional fault trends are lacking. To address this need, GIS and spatial
analyses were used to quantitatively delineate Newberry vent-distribution patterns and test for
structural controls on magma emplacement.
This paper presents the second installment of research on the geologic, morphologic, and
spatial characteristics of basaltic cinder cones at Newberry Volcano. Previous companion work
includes that of Taylor et al. (2003) and Giles et al. (2003). As population density is rapidly
increasing in Bend and surrounding areas (annual avg. growth = 21%; U.S. Census Bureau,
2003), this ongoing investigation may have important implications for volcanic hazards
assessment in the region (after Sherrod et al., 1997).
3. GEOLOGIC SETTING
Newberry Volcano is an elongated shield that extends 60 km in a north-south direction
and 30 km from east to west, covering an area greater than 1600 km2. The summit is marked by
a caldera that is 7 by 5 km across (Figures 2 and 3), with eruptive products ranging in age from
Holocene to Late Pleistocene (MacLeod and Sherrod, 1988; Jensen, 2002).
Newberry Volcano lies at the west end of the High Lava Plains about 65 km east of the
Cascade Range (Figure 1). Owing to its location, Newberry displays tectonic and compositional
characteristics of the Cascade Range, High Lava Plains, and Basin and Range (MacLeod and
others, 1981; MacLeod and Sherrod. 1988). The volcano is also positioned at the younger end of
a sequence of rhyolite domes and caldera-forming ash-flow tuffs that decrease in age from 10
m.y. in southeastern Oregon to less than 1 m.y. near the caldera (Figure 1).
As stated above, Newberry is located in a complex, extensional tectonic setting
dominated by Pliocene to Quaternary faults (Figures 1 and 2) (MacLeod and others, 1981;
MacLeod and Sherrod. 1988). The Brothers fault zone is a major west-northwest trending
domain of dominantly right-lateral strike slip faults that extend from southeastern Oregon to the
northeast flank of Newberry, where the faults are buried by Quaternary lava flows (MacLeod and
others, 1981; MacLeod and Sherrod. 1988). The north-northwest trending Tumalo fault zone
extends from the east side of the Cascades to the lower northern flanks of Newberry, where older
lava flows are offset by this fault system. Along the southern flanks of Newberry, the northnortheast trending Walker Rim fault zone offsets older flows (Figures 1 and 2).
The flanks of Newberry Volcano are covered mostly by basaltic andesite lava flows with
subordinate amounts of basalt and andesite lavas (Figure 2). Flow rocks are typically porphyritic
10
with abundant plagioclase phenocrysts and lesser amounts of olivine that resembles basalt, but
most are basaltic andesite with SiO2 values of 54-55 wt.% and compositional characteristics
similar to calc-alkaline flows in Cascade Range (MacLeod and Sherrod. 1988). Holocene flow
rocks are subdivided relative to the Mazama ash-fall deposits into younger than 6,850 and older
than 6,850 (MacLeod and others, 1981). The Mazama pumice deposit, which mantles the area
around Newberry with up 1 m of ash and lapilli, was erupted from Mt. Mazama to form Crater
Lake ~6800 years ago (6845+/-50 C14 yr B.P; Bacon, 1983).
Cinder cones and related lava flows are most abundant on the north and south flanks of
Newberry, less common on the east flank, and uncommon on the west flank (Figures 2, 3, and 4).
Many cones are aligned, and previous workers have identified three broad zones based on these
arrays (MacLeod and others, 1981; MacLeod and Sherrod. 1988). On the south flank, the cones
display a conspicuous north-northeast trend, sub-parallel with the Walker Rim fault zone
(Figures 2 and 3). On the north flank, the cones form a wider north-northwest trending array that
parallels the Tumalo fault zone. Some on the north flank also display curved arrangements
parallel to caldera walls and are presumably related to local stresses within volcano (MacLeod
and Sherrod. 1988) (Figure 2). The work presented herein provides a quantitative framework
from which to evaluate cinder cone alignment patterns.
4. METHODOLOGY
Numerous workers have observed that vent-alignment patterns are a common occurrence
in cinder cone fields, however early work was based on visual analysis of lineament patterns.
The subjective nature of this work led to variable results and the geological significance was
difficult to evaluate. Research activities in the late 1980’s focused on development of rigorous
statistical procedures that could be applied to point-based analysis of cinder cone distributions.
Approaches are varied and include univariate statistics (Porter, 1972; Settle, 1979) density
mapping (Porter, 1972; Connor, 1987) Monte Carlo simulations (Lutz, 1986; Zhang and Lutz,
1989), fourier analysis (Connor, 1987), and cluster analysis (Connor, 1990). While these
quantitative methods have been applied in a wide variety of volcanic settings in North America,
none have been utilized to analyze cinder-cone distribution at Newberry Volcano.
Observed cone patterns were tested for randomness and spatial anisotropy using a
combination of quadrat analysis (Komogorov-Simirnov test) and comparative-distribution
analysis via Monte Carlo simulations. The latter employed the “line-azimuth” method of Lutz
(1986) and the “point-density” method of Zhang and Lutz (1989). Both techniques consider
cinder cone positions to represent nodal points connecting a set of lattice lines. Newberry cone
positions and lattice orientations were systematically compared to simulated random point
patterns. Statistical filtering was used to identify anisotropic distributions and delineate conealignment patterns. Statistically significant cone-distribution patterns were subsequently
compared to fault trends to assess the degree to which magma emplacement was guided by
regional tectonic stress fields. The analytical techniques used in this study are graphically
depicted in Figure 5.
A select set of Newberry cinder cones (n = 296) were analyzed by applying the statistical
techniques in a geographic information system. Data compilation and spatial analysis was
conducted using a suite of GIS-related software including ArcView (ESRI), ArcGIS (ESRI),
Idrisi (Clark Labs), Cartalynx (Clark Labs), and Surfer (Golden Software). Cone-vent positions
were derived from a variety of data sources including a digitized version of the published
Newberry geologic map (1:62,500; MacLeod and others, 1995; Giles and others, 2003), USGS
10-m digital elevation models (DEM), and 1:24000 digital orthophotoquads (DOQ). The sample
11
population included all single and composite basaltic cinder cones mapped as "Qc" by MacLeod
and others (1995). Cone locations were further subdivided into northern (n=149) and southern
(n=147) domains to test for mutually independent relations between the three fault zones. The
analysis did not include eruptive products mapped as part of the fissure-vent systems
surrounding the caldera region.
5. RESULTS
Fault segment analysis reveals three dominant azimuthal trends in the region: 310-320 for
the Brothers fault zone, 330-340 for the Tumalo fault zone, and 45-55 for the Walker Rim
(Figure 6).
Results of the Komogorov-Simirnov tests reject the null hypothesis at the 95%
confidence interval, documenting that Newberry cinder cones are not randomly distributed.
Preferred cone alignment directions derived from the line-azimuth analysis are presented in
Figures 7, 8, and 9. Cone-point density results are summarized in Figure 10. Refer to figure
captions for discussion of techniques and methodology for establishing statistical significance.
The Monte Carlo-based analyses identify three significant cone alignments in the
southern domain (dominant azimuth directions = 0, 10-35, 340-350), and three in the northern
(80, 280-295, 310). Combined data from both domains strengthens the statistical significance of
the 310 and 340-350 cone alignment directions. Table 1 presents a summary of results from the
fault and cone trend analyses at Newberry Volcano. Figure 11 is a summary map showing
regional fault trends and cinder cone lineament patterns at Newberry Volcano.
6. DISCUSSION AND CONCLUSION
The above results suggest that the Brothers and Tumalo fault zones had a detectable
control on cinder-cone emplacement in both the northern and southern domains, whereas the
Walker Rim is poorly correlated to significant cone-alignment patterns. The absence of direct
cone alignment with the Walker Rim trend is notable (Figure 11), and an unexpected departure
from the qualitative observations cited by MacLeod and Sherrod (1988). Significant cinder cone
alignments with azimuthal trends of 10-35, 80, and 280-295 suggest additional control by
structural conditions other than those represented by mapped surface faults. The north-northeast
cone alignment patterns are consistent with the hypothesis that the Walker Rim and Tumalo
faults merge to form a single arc-shaped fracture zone at depth. These results combined with
cone-volume distribution data published elsewhere (Taylor and others, 2003), suggest that the
Tumalo Fault Zone is a dominant structural control on magma emplacement at Newberry
Volcano. This study provides a preliminary framework from which to pose additional questions
regarding the complex interaction between stress regime, volcanism, and faulting in central
Oregon.
7. ACKNOWLEDGMENTS
Work on this project was initially stimulated by group discussions related to the Fall 2000
Friends of the Pleistocene, Pacific Northwest Cell, field trip to Newberry Volcano. Special
thanks are extended to the FOP organizers and presenters for elucidating many of the interesting
research problems associated with Newberry. Portions of this study were funded by the College
of Liberal Arts and Sciences, the Faculty Development Grant Program, the ASWOU Student
Technology Fee Committee, and the PT3 Project at Western Oregon University. Tony Faletti,
12
Diane Horvath, Diane Hale, and Ryan Adams are also acknowledged as exemplary WOU Earth
Science students who assisted with the tedious task of map digitization. Bill Kernan at WOU
University Computing provided staff programming services for portions of the statistical
analysis.
8. REFERENCES CITED
Bacon, C.R., 1983, Eruptive history of Mount Mazama, Cascade Range, U.S.A.: Journal of
Volcanology and Geothermal Research, v. 18, p. 57-115.
Carr, M.J., 1976, Underthrusting and normal faulting in northern Central America: Geological
Society of America Bulletin, v. 87, p. 825-829.
Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.A., and Chitwood,
L.A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the Friends of the
Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
Connor, C.B., 1987, Cluster analysis and 2-d fourier analysis of cinder cone distributions,
Central Mexico and SE Guatamal: Eos, vol. 68, no. 44, p. 1526.
Connor, C.B., 1990, Cinder cone clustering in the TransMexican Volcanic Belt: Implications for
structural and petrologic models: Journal of Geophysical Research, v. 95, p. 19,395-19,405.
Connor, C.B. and Condit, C.D., 1989, Evidence of structural controls on vent distribution:
Springerville volcanic field, Arizona: Geologic Society of America Abstracts with Programs, v.
21, A15.
Connor, C.B., Condit, C.D., Crumpler, L.S., and Aubele, J.C., 1992, Evidence of regional
structural controls on vent distribution: Springerville volcanic field, Arizona: Journal of
Geophysical Research, v. 97, p.12,349-12,359.
Giles, D.E.L., Taylor, S.B., and Templeton, J.H., 2003, Compilation of a digital geologic map
and spatial database for Newberry volcano, central Oregon: A framework for comparative
analysis: Geological Society of America Abstracts with Programs, v. 35, no. 6, p. 189.
Hasenaka, T., and Carmichael, I.S.E., 1985, The cinder cones of Michoacan-Guanajuato central
Mexico: Their age, volume and distribution, and magma discharge rate: Journal of Volcanology
and Geothermal Research, v. 25, p. 105-124.
Jensen, R.A., 2000, Roadside Guide to the Geology of Newberry Volcano, 3rd ed.:
CenOreGeoPub, Bend, Oregon, 168 pp.
Jensen, R.A., and Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.
A., and Chitwood, L. A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the
Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
Kear, D., 1964, Volcanic alignments north and west of New Zealand’s central volcanic region:
New Zealand Journal of Geology and Geophysics, v. 7, p. 24-44.
13
Lutz, T.M., 1986, An analysis of the orientations of large-scale crustal structures: a statistical
approach based on areal distributions of pointlike features: Journal of Geophysical Research, vol.
91, no. B1, p. 421-434.
MacLeod, N. S., and Sherrod, D. R., 1988, Geologic evidence for a magma chamber beneath
Newberry Volcano, Oregon: Journal of Geophysical Research, v. 93, p. 10,067-10,079.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and McKee, E.H., 1981, Newberry Volcano,
Oregon, in Johnston, D. A., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in
Washington, Idaho, and northern California: U.S. Geological Survey Circular 838, p. 85-103.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and Jensen, R.A., 1995, Geologic Map of
Newberry Volcano, Deschutes, Klamath, and Lake Counties, Oregon: U.S. Geological Survey
Miscellaneous Geologic Investigations Map I-2455, scales 1:62,500 and 1:24,000.
Nakamura, K., 1977, Volcanoes as possible indicators of tectonic stress orientation – Principles
and proposal: Journal of Volcanology and Geothermal Research, v. 2, p. 1-16.
Porter, S.C., 1972, Distribution, morphology, and size frequency of cinder cones on Mauna Kea
volcano, Hawaii: Geological Society of America Bulletin, v. 83, p. 3607-3612.
Settle, M., 1979, The structure and emplacement of cinder cone fields: American Journal of
Science, v. 279, p. 1089-1107.
Sherrod, D.R., Mastin, L.G., Scott, W.E., and Schilling, S.P., 1997, Volcano hazards at
Newberry Volcano, Oregon: U. S. Geological Survey, Open-file Report 97-513, 14 pp.
Taylor, S.B., Templeton, J.H., and Giles, D.E.L., 2003, Cinder Cone Morphometry and Volume
Distribution at Newberry Volcano, Oregon: Implications for Age Relations and Structural
Control on Eruptive Process: Geological Society of America Abstracts with Programs, v. 35, no.
6, Fall National Meeting, Seattle.
U.S. Census Bureau, 2003, Census data for the state of Oregon: online resource,
http://www.census.gov.
Wadge, G., and Cross, A., 1988, Quantitative methods for detecting aligned points: an
application to the volcanic vents of the Michoacan-Guanajuato volcanic field, Mexico: Geology,
vol. 16, p. 815-818.
Walker, G.W., and MacLeod, N.S., 1991, Geologic Map of Oregon: U.S. Geological Survey,
Scale, 1:500,000.
Wood, C.A., 1980, Morphometric evolution of cinder cones: Journal of Volcanology and
Geothermal Research, v. 7, p. 387-413.
Zhang, D. and Lutz, T., 1989, Structural control of igneous complexes and kimberlites: a new
statistical methoc: Tectonophysics, v. 159, p. 137-148.
14
FIGURE / TABLE CAPTIONS
Figure 1. Generalized map of Oregon emphasizing the regional geologic and tectonic framework
of Newberry Volcano. (After Walker and MacLeod, 1991).
Figure 2. Generalized geologic map of Newberry Volcano (after Jensen, 2000).
Figure 3. Atlas-relief map of Newberry Volcano showing central caldera and related cinder cone
fields. Note prominent vent alignments. Composite DEM concatenated from 7.5-minute USGS
10-m elevation models.
Figure 4A. Profile view of Newberry Volcano showing central caldera region and related cindercone field in foreground (red outlines).
Figure 4B. Aerial view of Lava Butte cinder cone (6160 +/- 70 C14 yrs) (Sept. 3, 1986, ©R.A.
Jensen).
Figure 5. Diagrammatic summary of statistical procedures used to identify cinder cone
alignment patterns at Newberry Volcano (after Lutz, 1986; and Zhang and Lutz, 1989).
Figure 7. Frequency histograms showing the results of the line-azimuth analysis method (Lutz,
1986) as applied to cinder cone patterns in the north and south fields at Newberry Volcano.
Graph A is the raw frequency distribution for line-azimuths drawn between cinder cone points (n
= 296). Graph B represents the mean distribution for 300 random cone simulations (n = 296 /
replicate). The strong north mode reflects the elongated shape of the Newberry complex, with
preferential line-azimuths occurring in a north-south direction. Graph C shows normalized cone
data, transformed to remove the shape effects by the following equation:
Fnorm = (Fexp / Favg) * Fobs
where Fnorm = normalized bin frequency, Fexp = expected bin frequency, Favg = average
random bin frequency, and Fobs = observed bin frequency. Azimuth bins with frequencies
greater than the critical value are signifcant at the 95% confidence interval.
Figure 8. Frequency histograms showing the results of the line-azimuth analysis method (Lutz,
1986) as applied to cinder cone patterns in the north field at Newberry Volcano. See caption in
Figure 7 for discussion. Azimuth bins with frequencies greater than the critical value are
signifcant at the 95% confidence interval.
Figure 9. Frequency histograms showing the results of the line-azimuth analysis method (Lutz,
1986) as applied to cinder cone patterns in the south field at Newberry Volcano. See caption in
Figure 7 for discussion. Azimuth bins with frequencies greater than the critical value are
signifcant at the 95% confidence interval.
Figure 10. Frequency histogram showing the results of the cone-point density analysis method
of Zhang and Lutz (1989). The technique utilized a set of 1-km wide filter strips with 50%
overlap, cast over both the Newberry and random cone-point distribution maps. The filter strip15
sets were sequentially rotated at 5-degree azimuth increments, with a tally of the total number of
cones in each and calculation of cone density per unit area. Newberry strip cone densities were
compared to random simulation patterns, with data normalized according to the following
equation:
D = (d – M) / S
where D = normalized cone density, d = actual cone density (no. / sq. km), M = average density
of random points (n = 30 reps), and S = random standard deviation. Significant cone lineaments
and strip locations were then identified as those with point densities greater than 2 to 3 standard
deviations above random average. Significant cone lineaments identified by the method are
mapped on Figure 11, with the statistical results summarized in Table 1.
Figure 11. Summary map showing regional fault trends and cinder cone lineament patterns at
Newberry Volcano. Abbreviations used on cone alignment diagram include: BFZ = Brothers
Fault Zone, TFZ = Tumalo Fault Zone, and WRFZ = Walker Rim Fault Zone. Note the absence
of cone-alignment trends directly parallel to the Walker Rim Fault Zone.
Table 1. Summary matrix of Newberry fault-trend and cinder cone analyses.
16
Geological Society of America Fall 2003 Meeting, Seattle, Washington
Session No. 172 Quaternary Geology/Geomorphology III: Glaciers, Volcanoes, Caves, and
Isotopes
Cinder Cone Morphometry and Volume Distribution at Newberry Volcano, Oregon:
Implications for Age Relations and Structural Control on Eruptive Process
Abstract
Newberry Volcano of central Oregon covers greater than 1300 km2 and is associated with
over 400 basaltic cinder cones and fissure vents (Holocene-Late Pleistocene). Digital geologic
maps and 10-m USGS DEMs were compiled with 182 single cones selected for morphometric
and volume analyses using GIS. This robust data set provides a framework from which to
evaluate cone volume distributions and relative ages in the context of erosional degradation
models.
Based on visual inspection of DEM-derived shaded relief maps, each cone was qualitatively
ranked with a morphology classification ranging from 1 (well defined cone-crater morphology)
to 7 (very poorly defined cone-crater morphology). Morphometric measurements include cone
height (Hc), average cone slope (Sc), long-axis diameter (Dl), short axis diameter (Ds), and
height:width ratio (Hc/Wc where Wc=(Dl+Ds)/2). Individual cone DEMs were extracted and
volumes (Vc) calculated using a kriging-based algorithm. Average slopes were derived from 10m elevation nodes contained within cone polygons. Results according to qualitative morphology
rank are summarized as follows: (A) Frequency (no.) 1=11, 2=21, 3=10, 4=35, 5=11, 6=35,
7=59; (B) Average Vc (m3) 1=1.46 x 107, 2=1.53 x 107, 3=1.25 x 107, 4=4.88 x 106, 5=4.65 x
106, 6=3.07 x 106, 7=1.10 x 106; (C) Average Sc (deg) 1=19.9, 2=18.2, 3=18.1, 4=14.9,
5=14.4, 6=11.9, 7=10.2; (D) Average Hc (m) 1=132, 2=124, 3=126, 4=76, 5=78, 6=59, 7=50;
(E) Average Hc/Wc 1=0.18, 2=0.20, 3=0.19, 4=0.15, 5=0.14, 6=0.13, 7=0.13. Existing cone
degradation models demonstrate that with increasing cone age, Sc, Hc, and Hc/Wc decrease,
respectively. Systematic t-tests (a=0.05) of these parameters between morphology classes
statistically separates cones into two groups: (1) ”Morphometric Group I” = ranks 1-3, and (2)
”Morphometric Group II” = ranks 4-7. Spatial analysis of cone-volume distributions shows
maxima oriented NW-SE, parallel to regional fault trends (Tumalo Fault and Northwest Rift
zones).
The above results suggest that there are two distinct age populations of cinder cones at
Newberry. Parallel alignment of cone-volume maxima with known fault trends implies that
these structures have an important control on eruptive process in the region. This study provides
a framework to guide future geomorphic analysis and radiometric age dating of cinder cones at
Newberry Volcano.
17
Introduction
Newberry Volcano is located in central Oregon, in close proximity to the cities of Bend and
LaPine (Figure 1). With an estimated volume of 450 km3, Newberry is one of the largest
volcanoes in the contiguous United States. It is an elongated shield that extends 60 km long
north south and 30 km wide east west; the summit is marked by a caldera that is 7 by 5 km
across (Figures 2 and 3) (MacLeod and Sherrod, 1988). This broad shield complex covers greater
than 1600 km2 and is associated with over 400 basaltic cinder cones and fissure vents
(Holocene-Late Pleistocene; Jensen 2002) (Figure 2). The large number of cinder cones
provides an important geologic framework from which to conduct morphometric analyses, test
existing erosional degradation models, and decipher controls on eruptive magnitude and
frequency.
This work represents preliminary morphometric and volume analyses of 182 single cinder
cones distributed across Newberry Volcano. Data were compiled from digital geologic maps and
10-m DEMs using GIS (Giles and others, 2003). The results are placed in the context of relative
age dating and structural control on volcanic process. As population density is rapidly increasing
in Bend and surrounding areas (annual avg. growth = 21%; U.S. Census Bureau, 2003), results
of this ongoing investigation may have important implications for volcanic hazards assessment
(after Sherrod et al., 1997).
Geologic Setting
Newberry Volcano lies at the west end of the High Lava Plains about 65 km east of the
Cascade Range (Figure 1). Owing to its location, Newberry displays tectonic and compositional
characteristics of the Cascade Range, High Lava Plains, and Basin and Range (MacLeod and
others, 1981; MacLeod and Sherrod. 1988). The volcano is also positioned at the younger end of
a sequence of rhyolite domes and caldera-forming ash-flow tuffs that decrease in age from 10
m.y. in southeastern Oregon to less than 1 m.y. near the caldera (Figure 1).
Newberry is located in a complex, extensional tectonic setting dominated by Pliocene to
Quaternary faults (MacLeod and others, 1981; MacLeod and Sherrod. 1988). Several major fault
zones surround and converge near Newberry, including the Brothers fault zone, the Tumalo fault
zone, and the Walker Rim fault zone (Figures 1 and 2). The Brothers fault zone is a major westnorthwest trending domain of dominantly right-lateral strike slip faults that extend from
southeastern Oregon to the northeast flank of Newberry, where the faults are buried by
Quaternary lava flows (MacLeod and others, 1981; MacLeod and Sherrod. 1988). The northnorthwest trending Tumalo fault zone extends from the east side of the Cascades to the lower
northern flanks of Newberry, where older lava flows are offset by
18
this fault system. Along the southern flanks of Newberry, the north-northeast trending
Walker Rim fault zone offsets older flows (Figures 1 and 2).
The flanks of Newberry Volcano are covered mostly by basaltic andesite lava flows with
subordinate amounts of basalt and andesite lavas (Figure 2). Flow rocks are typically porphyritic
with abundant plagioclase phenocrysts and lesser amounts of olivine that resembles basalt, but
most are basaltic andesite with SiO2 values of 54-55 wt.% and compositional characteristics
similar to calc-alkaline flows in Cascade Range (MacLeod and Sherrod. 1988). Holocene flow
rocks are subdivided relative to the Mazama ash-fall deposits into younger than 6,850 and older
than 6,850 (MacLeod and others, 1981). The Mazama pumice deposit, which mantles the area
around Newberry with up 1 m of ash and lapilli, was erupted from Mt. Mazama to form Crater
Lake ~6800 years ago (6845+/-50 C14 yr B.P; Bacon, 1983).
Cinder cones and related lava flows are most abundant on the north and south flanks of
Newberry, less common on the east flank, and uncommon on the west flank (Figures 2 and 3).
Many cones are aligned, and previous workers have identified three broad zones based on these
arrays (MacLeod and others, 1981; MacLeod and Sherrod. 1988). On the south flank, the cones
display a conspicuous north-northeast trend, co-linear with the Walker Rim fault zone (Figure 2).
On the north flank, the cones form a wider north-northwest trending array that parallels the
Tumalo fault zone. Some on the north flank also display curved arrangements parallel to caldera
walls and are presumably related to local stresses within volcano (MacLeod and Sherrod. 1988)
(Figure 2). MacLeod and Sherrod (1988) interpreted the cone and vent alignments to represent
the surface expression of dikes at depth that formed in response to regional stress fields. They
observed that the apparent curvilinear distribution of cinder cones and fissure vents on the north
and south flanks of Newberry trend mostly parallel to the Walker Rim and Tumalo fault zones,
suggesting that these fault zones form a single arc-shaped fault zone beneath Newberry.
MacLeod and Sherrod (1988) also suggested that north-northwest trending cones and fissure
vents are relatively younger than those trending north-northeast. The work presented herein
provides a quantitative framework from which to evaluate this interpretation.
Methodology
A select set of Newberry cinder cones (n = 182) were analyzed by measuring a suite of
morphometric parameters that are commonly used to quantitatively characterize shape, eruptive
volume, and relative age. Data sources included a digitized version of the published Newberry
geologic map (1:62,500; MacLeod and others, 1995; Giles and others, 2003), USGS 10-m digital
elevation models (DEM), and 1:24000 digital orthophotoquads (DOQ). The sample population
was selected on the basis of the following criteria: (1) basaltic cinder cones mapped as "Qc" by
MacLeod and others (1995), (2) single cones that are not part of a fissure-vent system, (3) intact
cones that do not appear to be topographically breached, (4) exposed cones that are not
19
significantly covered by younger lava flows, and (5) cones that are clearly separated from nearest
neighbors (e.g. Lava Butte, Figure 3B).
Individual cone DEMs were extracted from the USGS 10-m quadrangles and analyzed using
a suite of GIS-related software including ArcView (ESRI), ArcGIS (ESRI), Idrisi (Clark Labs),
Cartalynx (Clark Labs), and Surfer (Golden Software). Based on visual inspection of DEMderived shaded relief maps, each cone was qualitatively ranked with a morphology classification
ranging from 1 (well defined cone-crater morphology) to 7 (very poorly defined cone-crater
morphology) (Table 1, Figure 4). Morphometric techniques were modified from those
developed by Scott and Trask (1971), Porter (1972), and Wood (1980). Parameters include cone
height (Hc), average cone slope (Sc), long-axis diameter (Dl), short axis diameter (Ds), and
height:width ratio (Hc/Wc where Wc=(Dl+Ds)/2). Long and short axes (Dl and Ds,
respectively) were digitized from cone polygon outlines as defined by unit Qc from MacLeod
and others (1995). Cone height and slope were derived from 10-m elevation nodes contained
within Qc polygons. Finally, cone volumes were calculated from the DEMs by clipping the
edifice footprint (2x the cone-bounding rectangle), masking the cone relief to zero, and regridding the "masked" cone using a kriging-based algorithm (Figure 5). Cone volumes (Vc)
were derived by subtracting the masked cone DEM (Figure 5B) from the original footprint
(Figure 5A). Systematic t-test analyses (a = 0.05) were subsequently used to conduct means
comparisons between cone morphology rating classes.
Results
Morphometric Data
Figure 6 is a location map showing the selected Newberry cinder cones and their respective
morphology ratings as described above. Morphometric results for each of the seven
morphology-rating classes are listed in Table 2 and displayed in Figure 7. The results for each
class are summarized as follows: (A) Frequency (no.) 1=11, 2=21, 3=10, 4=35, 5=11, 6=35,
7=59; (B) Average Vc (m3) 1=1.46 x 107, 2=1.53 x 107, 3=1.25 x 107, 4=4.88 x 106, 5=4.65 x
106, 6=3.07 x 106, 7=1.10 x 106; (C) Average Sc (deg) 1=19.9, 2=18.2, 3=18.1, 4=14.9,
5=14.4, 6=11.9, 7=10.2; (D) Average Hc (m) 1=132, 2=124, 3=126, 4=76, 5=78, 6=59, 7=50;
(E) Average Hc/Wc 1=0.18, 2=0.20, 3=0.19, 4=0.15, 5=0.14, 6=0.13, 7=0.13.
T-Test Results
Results of systematic t-tests (a=0.05) between morphology rating categories are listed in Table 3.
Mean cone slope (Sc), cone height (Hc) and height:width ratios (Hc/Wc) were compared to
identify morphometric similarities or differences between rating categories. Systematic t-tests
20
statistically separated cone rating categories into two groups: (1) ”Morphometric Group I” =
ranks 1-3, and (2) ”Morphometric Group II” = ranks 4-7 (Table 3, Figure 7).
Cone Volume Analysis
Results of cone volume calculations are summarized in Table 4. Cone volumes range from
1.97x103 m3 to 4.53x107 m3, with an average of 5.62x106 m3. Volume data were also
contoured to show spatial distribution with respect to regional structure (Figure 8). Cones with
the highest volumes occur on the north flank of Newberry. Volume maxima both north and
south of the summit caldera are broadly co-linear with the north-northwest trending Tumalo fault
zone.
DISCUSSION
Existing cone degradation models demonstrate that as cone age increases, Sc, Hc, and Hc/Wc
decrease, respectively (e.g. Scott and Trask, 1971; Dowrenwend and others, 1986; Hooper and
Sheridan, 1998). Cones degrade over time by both diffusive and advective erosion processes,
with mass transfer from hillslope to debris apron and filling of the central crater (Dohrenwend
and others, 1986; Blauvett, 1998; Rech and others, 2001). The net result is reduction of cone
height and slope through time coupled with the loss of crater definition.
GIS-based analyses presented in this paper indicate that there are are two distinct populations
of cinder cones at Newberry. Based on comparison with similar studies, these data suggest that
cones included in Morphometric Group I are relatively “young” compared to those in Group II,
which are relatively “old”. As such, Group I Sc and Hc/Wc values average 19-20o and 0.19,
respectively, while Group II values average 11-15o and 0.14. By comparing Newberry data with
age-calibrated cone morphometry studies in Arizona (Hooper and Sheridan, 1998), the results
imply that both Group I and Group II cones fall within a “Holocene-Latest Pleistocene” age
category. However, higher resolution chronometry is required to more definitively establish age
trends in the cones selected for this study. Based on preliminary comparison with dated eruptive
events at Newberry (Jensen, 2000), it is uncertain if the morphometric groupings delineated in
this study are a function of age differences (i.e. degradational processes) or a combination of
other variables such as climate, post-eruption cone burial, lava composition, and episodic
(“polygenetic”) eruption cycles. Further radiometric and geomorphic dating studies will be
required to definitively decipher the factors controlling the two morphometric groupings
identified in this work.
Cone clustering and alignment patterns are commonly recognized at volcanic fields (Porter,
1972; Settle, 1979; Connor, 1990). Spatial-distribution patterns of Newberry morphometric
groups (Figure 9) shows a northwest-southeast alignment of Group I cones and a northeast21
southwest alignment of some Group II cones. While care must be taken when inferrring linear
trends from cinder cone arrays, these data lend support to the hypothesis of MacLeod and
Sherrod (1988) that north-northwest trending clusters are relatively younger than those oriented
north-northeast. Regional and local tectonic stress fields are often interpreted as the primary
factor controlling such cone distribution patterns. Parallel alignment of Newberry cone-volume
maxima with the Tumalo fault zone implies that this structure has an important control on
eruptive process. This observation supports the contention of MacLeod and Sherrod (1998) that
faulting and regional tectonic stress fields structurally control mafic eruptions at Newberry.
CONCLUSION
Morphometric and volume-distribution analyses of cinder cones at Newberry Volcano
suggest that cones are systematically organized in both space and time. Two morphometric
groupings of cinder cones are statistically recognized at the 95% confidence level. Possible
controlling factors include degradation processes, age differences, climate, post-eruption cone
burial, lava composition, and episodic (polygenetic) eruption cycles. Parallel alignment of conevolume maxima with known fault trends implies that these structures have an important control
on eruptive processes in the region. This study provides a preliminary framework to guide future
geomorphic analyses and radiometric age dating of Newberry cinder cones.
ACKNOWLEDGMENTS
Work on this project was initially stimulated by group discussions related to the Fall 2000
Friends of the Pleistocene, Pacific Northwest Cell, field trip to Newberry Volcano. Special
thanks are extended to the FOP organizers and presenters for elucidating many of the interesting
research problems associated with Newberry. Portions of this study were funded by the College
of Liberal Arts and Sciences, the Faculty Development Grant Program, the ASWOU Student
Technology Fee Committee, and the PT3 Project at Western Oregon University. Tony Faletti,
Diane Horvath, Diane Hale, and Ryan Adams are also acknowledged as exemplary WOU Earth
Science students who assisted with the tedious task of map digitization.
References Cited
Bacon, C.R., 1983, Eruptive history of Mount Mazama, Cascade Range, U.S.A.: Journal of Volcanology and
Geothermal Research, v. 18, p. 57-115.
22
Blauvett, D.J., 1998, Examples of scoria cone degradation in the San Francisco volcanic field, Arizona: M.S. Thesis,
State University of New York at Buffalo, Amherst, NY, 127 p.
Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.A., and Chitwood, L.A., eds., What’s
New at Newberry Volcano, Oregon: Guidebook for the Friends of the Pleistocene Eighth Annual Pacific
Northwest Cell Field Trip, p. 27-30.
Connor, C.B., 1990, Cinder cone clustering in the TransMexican Volcanic Belt: Implications for structural and
petrologic models: Journal of Geophysical Research, v. 95, p. 19,395-19,405.
Dohrenwend, J.C., Wells, S.G., and Turrin, B.D., 1986, Degradation of Quaternary cinder cones in the Cima
volcanic field, Mojave Desert, California: Geological Society of America Bulletin, v.97, p. 421-427.
Giles, D.E.L., Taylor, S.B., and Templeton, J.H., 2003, Compilation of a digital geologic map and spatial database
for Newberry volcano, central Oregon: A framework for comparative analysis: Geological Society of
America Abstracts with Programs, v. 35, no. 6, p. 189.
Higgins, MW., 1973, Petrology of Newberry Volcano, Central Oregon: Geological Society of America Bulletin, v.
84, p. 455-488.
Hooper, D.M., and Sheridan, M.F., 1998, Computer-simulation models of scoria cone degradation: Journal of
Volcanology and Geothermal Research, v. 83, p. 241-267.
Jensen, R.A., 2000, Roadside Guide to the Geology of Newberry Volcano, 3rd ed.: CenOreGeoPub, Bend, Oregon,
168 pp.
Jensen, R.A., and Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R. A., and Chitwood,
L. A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the Friends of the Pleistocene
Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
MacLeod, N. S., and Sherrod, D. R., 1988, Geologic evidence for a magma chamber beneath Newberry Volcano,
Oregon: Journal of Geophysical Research, v. 93, p. 10,067-10,079.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and McKee, E.H., 1981, Newberry Volcano, Oregon, in Johnston,
D. A., and Donnelly-Nolan, J., eds., Guides to some volcanic terranes in Washington, Idaho, and northern
California: U.S. Geological Survey Circular 838, p. 85-103.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and Jensen, R.A., 1995, Geologic Map of Newberry Volcano,
Deschutes, Klamath, and Lake Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic
Investigations Map I-2455, scales 1:62,500 and 1:24,000.
Porter, S.C., 1972, Distribution, morphology, and size frequency of cinder cones on Mauna Kea volcano, Hawaii:
Geological Society of America Bulletin, v. 83, p. 3607-3612.
Rech, J.A., Reeves, R.W., and Hendricks, D.M., 2001, The influence of slope aspect on soil weathering processes in
the Springerville volcanic field, Arizona: Catena, v. 43, p. 49-62.
Scott, D.H., and Trask, N.J., 1971, Geology of the Lunar Crater volcanic field, Nye County, NV: U.S. Geological
Survey Professional Paper, 599-I, 22 p.
Settle, M., 1979, The structure and emplacement of cinder cone fields: American Journal of Science, v. 279, p.
1089-1107.
23
Sherrod, D.R., Mastin, L.G., Scott, W.E., and Schilling, S.P., 1997, Volcano hazards at Newberry Volcano, Oregon:
U. S. Geological Survey, Open-file Report 97-513, 14 pp.
U.S. Census Bureau, 2003, Census data for the state of Oregon: online resource, http://www.census.gov.
Walker, G.W., and MacLeod, N.S., 1991, Geologic Map of Oregon: U.S. Geological Survey, Scale, 1:500,000.
Wood, C.A., 1980, Morphometric evolution of cinder cones: Journal of Volcanology and Geothermal Research, v. 7,
p. 387-413.
Blauvett, D.J., 1998, Examples of scoria cone degradation in the San Francisco volcanic field,
Arizona: M.S. Thesis, State University of New York at Buffalo, Amherst, NY, 127 p.
Bloomfield, K., 1975, A late-Quaternary monogenetic volcanic field in central Mexico:
Geologische Reundschaue, v. 64, p. 476-497.
Carn, S.A., 2000, The Lamongan volcanic field, East Java, Indonesia: Physical volcanology,
historic activity and hazards: Journal of Volcanology and Geothermal Research, v. 95, p.
81-108
Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.A., and Chitwood,
L.A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the Friends of the
Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 27-30.
Condit, C.D., and Connor, C.B., 1996, Recurrence rates of volcanism in basaltic volcanic fields:
An example from the Springerville volcanic field, Arizona: Geological Society of
America Bulletin, v.108, p. 1225-1241.
Connor, C.B., 1990, Cinder cone clustering in the TransMexican Volcanic Belt: Implications for
structural and petrologic models: Journal of Geophysical Research, v. 95, p. 19,39519,405.
Connor, C.B., Condit, C.D., Crumpler, L.S., and Aubele, J.C., 1992, Evidence of regional
structural controls on vent distribution: Springerville volcanic field, Arizona: Journal of
Geophysical Research, v. 97, p.12,349-12,359.
Conway, F.M., Connor, C.B., Hill, B.E., Condit, C.D., Mullaney, K., and Hall, C.M., 1998,
Recurrence rates of basaltic volcanism in SP cluster, San Francisco volcanic field,
Arizona: Geology, v. 26, p. 655-658.
Dohrenwend, J.C., Wells, S.G., and Turrin, B.D., 1986, Degradation of Quaternary cinder cones
in the Cima volcanic field, Mojave Desert, California: Geological Society of America
Bulletin, v.97, p. 421-427.
Donnelly-Nolan, J.M., Champion, D.E., and Lanphere, M.A., 2000, North flank stratigraphy
revealed by new work at Newberry Volcano, Oregon, in, Jensen, R.A., and Chitwood,
L.A., eds., What's New at Newberry Volcano, Oregon: Guidebook for the Friends of the
Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 178-180.
24
Hasenaka, T. and Carmichael, I.S.E., 1985, A compilation of location, size, and
geomorphological parameters of volcanoes of the Michoacan-Guanajuato volcanic field,
central Mexico: Geofisica Internacional, v. 24, p. 577-607.
Hasenaka, T., and Carmichael, I.S.E., 1985, The cinder cones of Michoacan-Guanajuato central
Mexico: Their age, volume and distribution, and magma discharge rate: Journal of
Volcanology and Geothermal Research, v. 25, p. 105-124.
Head, J.W., and Wilson, L., 1989, Basaltic pyroclastic eruptions: Influence of gas-release
patterns and volume fluxes on fountain structure, and the formation of cinder cones,
spatter cones, rootless flows, lava ponds and lava flows: Journal of Volcanology and
Geothermal Research, v.37, p. 261-271.
Hooper, D.M., and Sheridan, M.F., 1998, Computer-simulation models of scoria cone
degradation: Journal of Volcanology and Geothermal Research, v. 83, p. 241-267.
Inbar, M., Hubp, J.L., and Ruiz, L.V., 1994, The geomorphological evolution of then Paricutin
cone and lava flows, Mexico, 1943-1990: Geomorphology, v. 9, p. 57-76.
Jensen, R.A., 2000, Roadside Guide to the Geology of Newberry Volcano, 3rd ed.:
CenOreGeoPub, Bend, Oregon, 168 pp.
Jensen, R.A., and Chitwood, L.A., 2000, Geologic overview of Newberry Volcano, in Jensen, R.
A., and Chitwood, L. A., eds., What’s New at Newberry Volcano, Oregon: Guidebook
for the Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 2730.
Jensen, R.A., Chitwood, L.A., Kuehn, S.C., Donnelly-Nolan, J.M., Reynolds, R.W., Connolly,
T.J., Castro, J., Linneman, S., Claeyssens, P.G., 2000, Newberry field trip guide, in
Jensen, R.A., and Chitwood, L.A., eds., What’s New at Newberry Volcano, Oregon:
Guidebook for the Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field
Trip, p. 5-26.
Jensen, R.A., and Chitwood, L.A., 2000, Lava Butte Eruption and Lake Benham, Oregon, in,
Jensen, R.A., and Chitwood, L.A., eds., What's New at Newberry Volcano, Oregon:
Guidebook for the Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field
Trip, p. 178-180.
Kuehn, S.C., and Foit, F.F., 2000, Silicic tephras of Newberry Volcano, in Jensen, R.A., and
Chitwood, L.A., eds., What’s New at Newberry Volcano, Oregon: Guidebook for the
Friends of the Pleistocene Eighth Annual Pacific Northwest Cell Field Trip, p. 135-163.
Luhr, J.F., and Carmichael, I.S.E., 1981, The Colima volcanic complex, Mexico: Part II. LateQuaternary cinder cones: Contributions to Mineralogy and Petrology, v. 76, p. 127-147.
MacLeod, N. S., and Sherrod, D. R., 1988, Geologic evidence for a magma chamber beneath
Newberry Volcano, Oregon: Journal of Geophysical Research, v. 93, p. 10,067-10,079.
25
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and McKee, E.H., 1981, Newberry Volcano,
Oregon, in Johnston, D. A., and Donnelly-Nolan, J., eds., Guides to some volcanic
terranes in Washington, Idaho, and northern California: U.S. Geological Survey Circular
838, p. 85-103.
MacLeod, N.S., Sherrod, D.R., Chitwood, L.A., and Jensen, R.A., 1995, Geologic Map of
Newberry Volcano, Deschutes, Klamath, and Lake Counties, Oregon: U.S. Geological
Survey Miscellaneous Geologic Investigations Map I-2455, scales 1:62,500 and
1:24,000.
Martin Del Pozzo, A.L., 1982, Monogenetic vulcanism in Sierra Chichinautzin, Mexico: Bulletin
of Volcanology, v. 45, p. 9-24.
Martinex-Hackert, B., and Bursik, M., 2001, Observations of hillslope degradation on scoria
cones in the San Francisco volcanic field, AZ, following the Hochderffer Fire, 1996:
Geological Society of America Abstracts with Programs, v. 233, p. 15.
Porter, S.C., 1972, Distribution, morphology, and size frequency of cinder cones on Mauna Kea
volcano, Hawaii: Geological Society of America Bulletin, v. 83, p. 3607-3612.
Rech, J.A., Reeves, R.W., and Hendricks, D.M., 2001, The influence of slope aspect on soil
weathering processes in the Springerville volcanic field, Arizona: Catena, v. 43, p. 49-62.
Scott, D.H., and Trask, N.J., 1971, Geology of the Lunar Crater volcanic field, Nye County, NV:
U.S. Geological Survey Professional Paper, 599-I, 22 p.
Settle, M., 1979, The structure and emplacement of cinder cone fields: American Journal of
Science, v. 279, p. 1089-1107.
Sherrod, D.R., Mastin, L.G., Scott, W.E., and Schilling, S.P., 1997, Volcano hazards at
Newberry Volcano, Oregon: U. S. Geological Survey, Open-file Report 97-513, 14 pp.
Walker, G.W., and MacLeod, N.S., 1991, Geologic Map of Oregon: U.S. Geological Survey,
Scale, 1:500,000.
Wells, S., McFadden, L.D., Renault, C.E., and Crowe, B.M., 1990, Geomorphic assessment of
late Quaternary volcanism in the Yucca Mountain area, southern Nevada: Implications
for the proposed high-level radioactive waste repository: Geology, v. 18, p. 549-553
Wood, C.A., 1980a, Morphometric evolution of cinder cones: Journal of Volcanology and
Geothermal Research, v. 7, p. 387-413.
Wood, C.A., 1980b, Morphometric analysis of cinder cone degradation: Journal of Volcanology
and Geothermal Research, v. 8, p. 137-160.
Wood, C.A, 1981, On the geometric form of volcanoes—comment: Earth and Planetary Science
Letters, v. 57, p. 451-452.
26
27