APPENDIX G
GEOLOGICAL REPORT
APPENDIX G:
GEOLOGICAL REPORT
Geological Setting at Primary and Alternative
Advanced Technology Solar Telescope (ATST) Sites,
Haleakalā High Altitude Observatories
by Ron Terry, Ph.D., Geometrician Associates
November 2005
Prepared for KC Environmental, Inc.
This report is in response to a request from KC Environmental, Inc. to review the geological
setting at the ATST primary and alternative sites (east side of Mees Observatory and Reber
Circle, respectively) at the Haleakalā High Altitude Observatories (HO), on Kolekole Cinder
Cone in Maui. My evaluation is based on primary and secondary information presented in the
Environmental Impact Statement Notice of Preparation for the ATST, additional published
sources, and one day of fieldwork on the site.
Over the course of Haleakalā’s formation, three distinct phases of eruption have taken place. The
first, called the Honomanu Volcanic Series, is responsible for the formation of Haleakalā’s
primitive shield and most likely, its three prominent rift zones. Honomanu lavas are exposed
over less than 1 percent of Haleakalā, but are believed to form the foundation of the entire
mountain to an unknown depth below sea level. The second series, or Kula Volcanic Series,
overlaid the previous Honomanu Series with its lava flows. Eruptions of this series were
considerably more explosive than its predecessor, leading to the formation of most of the cinder
cones along the three rift zones.
A period of inactivity followed the Kula Series, during which time erosion began to predominate,
leading to the formation of Haleakalā Crater and great valleys leading to the coast. After a period
of quiescence, now thought to be 120-150 ka in length (Sherrod et al 2003), additional eruptions,
called the Hana Volcanic Series, partially filled the deep valleys. Ash layers and cinder cones
ranging from a few feet high to more than a mile across at the base and 600 feet high were
deposited in the East and Southwest Rift Zones. Lava flows within the Haleakalā Southwest Rift
Zone vary from perhaps 200 to 20,000 years old. Six flows have erupted in this area within the
last 1,000 years. During the latest eruption sometime between 1650 and 1790, lava emerged from
two vents and flowed into La Perouse Bay, where a small peninsula was constructed. Recent
studies indicate that Haleakalā volcano may still be active, in light of the numerous eruptions
during the last 8,000 years (Bergmanis, E.C., J. M. Sinton and F. A. Trusdell 2000: 239-235).
Kolekole Cinder Cone, the crater of which is the site of the Haleakalā High Altitude
Observatories (Fig. 1), consists of cinder overlying alkalic lava flows classified as ankaramite
and dated to 128 ka +/-6 ka (Sherrod et al 2003). Its age and chemical composition (Chatterjee
et al 2005) indicates that it is probably part of the early Hana Volcanic series rather than the Kula
Volcanics, in which it was previously classified. A detailed study of Kolekole Cinder Cone was
undertaken as part of the Haleakalā Long Range Development Plan (LRDP, Appendix A,
Bhattacharji). The asymmetric cinder cone has steeper slopes on its western and northwestern
rims, with gentler slopes on the eastern and southern rims. According to report:
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GEOLOGICAL REPORT
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“…Kolekole Cinder Cone is composed primarily of various types of ankaramite
lava, spatter and cinder on the surface. The ankaramite lavas show a deep-crustal
magma (lava) source for the Kolekole cinder cone. The large volume of
phenocrysts (large crystals) in ankaramite lavas and the highly vesicular nature of
the lavas in the crater and rims of the Kolekole indicate rapid eruptions of lavas
from deep sub-surface magma (molten rock) –chambers under high volatile
pressures which degassed rapidly. The rims of the Kolekole were built up quickly
by rapid surges of phenocryst-bearing lavas, especially at the western and
northwestern margins.”
Figure 1. Project Site Location
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The report included a geological map and a cross-section of Kolekole Cinder Cone, which are
reproduced as Figures 2 and 3. The primary site for the ATST is just south of site “H” in Figure
1, in an area of mixed massive lava flows and cinder cones. A photograph of the typical surface
is shown in Figures 4 and 5. The proposed site consists of polygonal to sub-columnar lava
horizons which are broken into large blocks along horizontal and vertical joints. The near
horizontal ankaramite lava is ponded and agglutinated with spatter and some cinder as well (IfA’s
Haleakalā Long Range Development Plan (LRDP), Appendix A). Subsurface coring completed
during the site selection phase of ATST indicates that these lava horizons are several feet thick
and intermixed with cinder beds. Figure 6 is a view of the primary site from below, showing
how the massive horizontal surface lavas are a cap on a slope that reveals a mixture of lavas and
pyroclastic layers.
The alternate ATST site at Reber Circle is located just southeast of “A” on Figure 2, and is
illustrated in the photographs of Figures 7 and 8. This is an area of spatter and massive lava
flows, but it has been heavily altered by grading away of a local lava flow peak, and the site is
now flat and covered with graded material. A lava bomb from the site is illustrated in Figure 9.
Figure 2. Geologic Map (from Bhattacharji)
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Figure 3. Cross Section (from Bhattacharji)
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Figure 4. Photograph I of Primary Site
Figure 5. Photograph II of Primary Site
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GEOLOGICAL REPORT
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Figure 6. Photograph III of Primary Site
Figure 7. Photograph I of Alternative Site (Reber Circle)
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GEOLOGICAL REPORT
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Figure 8. Photograph II of Alternative Site (Reber Circle)
Figure 9. Volcanic Bomb at Alternative Site (Reber Circle)
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Neither site shows gross evidence of faulting, instability or mass wasting, and in a humanreferenced time scale, they do not appear to be geologically unsuitable sites. However, it should
be recognized that the Southwest Rift Zone of Haleakalā is considered by many to be an active
volcanic risk zone (Bhattacharji n.d.), and eruptions will eventually occur again.
According to project plans, if the ATST facility is located the primary site, the Reber Circle site
may be available for placement of excavated material. This material would be placed so as to
restore the pu’u (hill) that previously existed at this location before the construction of the Reber
circle experiment. The shape of the hill would be determined as much as possible from historical
photographs and geological records, and would extend the contours of the existing adjacent
slopes for a natural effect. The remains of the concrete Reber circle ring and the rock building at
the northeast end of the site would be removed. As part of this analysis, KC Environmental, Inc.
asked whether it would be possible to determine the appearance of the pu’u landform that was
present at the Reber Circle site before it was graded. Although it is only speculation, the
photographs in Figures 10 and 11, taken of nearby small promontories, are probably similar to
the removed landform and could be used as rough analogues. Such features are often between
20 and 50 feet in height. The “soil placement” area illustrated in Figure 12, which shows a
landform reconstructed from about 4,000 cubic yards of cut rock and “soil” generated from
material at the primary site that would be 24-feet high and 13,400 square feet in area at the base,
would provide a reasonable simulation of the previously existing topography.
Figure 10. Analogue I to Pre-Grading Landform at Reber Circle
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GEOLOGICAL REPORT
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Figure 11. Analogue I to Pre-Grading Landform at Reber Circle
Figure 12. Soil Placement Areas
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GEOLOGICAL REPORT
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REFERENCES
Bergmanis, E.C., J. M. Sinton and F. A. Trusdell. 2000. “Rejuvenated Volcanism Along the
Southwest Rift Zone, East Maui, Hawai‘i”. Bull. Volcanol., 62: 239-255.
Bhattacharji, S. “Geological Survey of the University of Hawai‘i Haleakalā Observatories and
Haleakalā Summit Region, East Maui, Hawai‘i.” App. A, UH IfA Haleakalā Long Range
Development Plan (LRDP), 2005.
Chatterjee, N., S Bhattacharji, and C. Fein. 2005 (in press). “Depth of alkalic magma reservoirs
below Kolekole cinder cone, Southwest rift zone, East Maui, Hawai‘i.” J. Volcanology and
Planetary Sciences.
Sherrod, D.R., Nishimitsu, Y., and Tagami, T. 2003. “New K-Ar ages and the geologic evidence
against rejuvenated-stage volcanism at Haleakalā, East Maui, a post shield-stage volcano of the
Hawaiian island chain.” Geol. Soc. of A. Bull. 11(6):683-694.
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