2019

U.S. Department of the Interior

U.S. Geological Survey

Geologic Map of the Central-Southeast Flank of 

Mauna Loa Volcano, Island of Hawaiʻi, Hawaii

By Frank A. Trusdell and John P. Lockwood

Pamphlet to accompany

Scientific Investigations Map 2932–B

Central-southeast flank of Mauna Loa volcano, Island of Hawaiʻi, Hawaii. Photograph by Frank A. Trusdell, U.S. Geological Survey.
U.S. Department of the Interior

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit https://store.usgs.gov.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Trusdell, F.A., and Lockwood, J.P., 2019, Geologic map of the central-southeast flank of Mauna Loa volcano, Island 

of Hawaiʻi, Hawaii: U.S. Geological Survey Scientific Investigations Map 2932–B, pamphlet 23 p., 2 sheets, scale 

1:50,000, https://doi.org/10.3133/sim2932B.

ISSN 2932-1311 (print)

ISSN 2932-132X (online)
iiii

Contents

Mauna Loa ......................................................................................................................................................1

Mapping Project....................................................................................................................................1

Central-Southeast Flank Mauna Loa..........................................................................................................1

Mapping Methods.................................................................................................................................1

Database ................................................................................................................................................3

Acknowledgments.........................................................................................................................................3 

Geology............................................................................................................................................................3

Central-Southeast Flank Mauna Loa.................................................................................................3

Volcanic Deposits .................................................................................................................................3

Flows ...........................................................................................................................................3

Age Groups ...................................................................................................................................4

Age Group 0 (Historical period: A.D. 1843 and younger).............................................4

Age Group 1 (pre-A.D. 1843–1,000 yr B.P.) ......................................................................4

Age Group 2 (1,000–2,000 yr B.P.) .....................................................................................4

Age Group 3 (2,000–3,000 yr B.P.) .....................................................................................4

Age Group 4 (3,000–4,000 yr B.P.) .....................................................................................4

Age Group 5 (4,000–5,000 yr B.P.) .....................................................................................4

Age Group 6 (5,000–6,000 yr B.P.) .....................................................................................4

Age Group 7 (6,000–7,000 yr B.P.; not in map area) .......................................................5

Age Group 8 (7,000–8,000 yr B.P.) .....................................................................................5

Age Group 9 (8,000–9,000 yr B.P.) .....................................................................................5

Age Group 10 (9,000–10,000 yr B.P.) .................................................................................5

Age Group 11 (10,000–15,000 yr B.P.) ...............................................................................5

Age Group 12 (15,000–20,000 yr B.P.; not in map area) .................................................5

Age Group 13 (20,000–30,000 yr B.P.) ...............................................................................5

Age Group 14 (30,000–100,000 yr B.P.; not in map area) ...............................................5

Age Group 15 (>100,000 yr B.P.) ........................................................................................5

Surficial Sedimentary Deposits..........................................................................................................5

Volcanic Ash..........................................................................................................................................5

Pāhala Ash ....................................................................................................................................5

Radiocarbon Data.................................................................................................................................6

Fault Systems.........................................................................................................................................6

Description of Map Units..............................................................................................................................7

Sedimentary Deposits..........................................................................................................................7

Volcanic Deposits .................................................................................................................................7

Lava Flows and Vent Deposits...................................................................................................7

Ka‘ū Basalt ..............................................................................................................7

Age Group 0 (A.D. 1843 and younger; Holocene) .................................................7

Age Group 1 (pre-A.D. 1843–1,000 yr B.P.; Holocene)..........................................7

Age Group 2 (1,000–2,000 yr B.P.; Holocene).........................................................8

Age Group 3 (2,000–3,000 yr B.P.; Holocene).......................................................10

Age Group 4 (3,000–4,000 yr B.P.; Holocene).......................................................11

Age Group 5 (4,000–5,000 yr B.P.; Holocene).......................................................12

Age Group 6 (5,000–6,000 yr B.P.; Holocene).......................................................12

Age Group 7 (6,000–7,000 yr B.P.; Holocene).......................................................13

Age Group 8 (7,000–8,000 yr B.P.; Holocene).......................................................13

Age Group 9 (8,000–9,000 yr B.P.; Holocene).......................................................13

Age Group 10 (9,000–10,000 yr B.P.; Holocene)...................................................13
iii iii

Age Group 11 (10,000–15,000 yr B.P.; Holocene and Pleistocene)...................14

Age Group 12 (15,000–20,000 yr B.P.; Pleistocene).............................................14

Age Group 13 (20,000–30,000 yr B.P.; Pleistocene).............................................14

Kahuku Basalt ...................................................................................................................14

Age Group 14 (30,000–100,000 yr B.P.; Pleistocene)...........................................15

Nīnole Basalt .....................................................................................................................15

Age Group 15 (>100,000 yr B.P.; Pleistocene)......................................................15

Distal Tephra Deposits ..............................................................................................................15

Selected References...................................................................................................................................16

Hawaiian Language References...............................................................................................................17

Appendix........................................................................................................................................................17

Tables

1. Summary statistics of historical (after A.D. 1843) eruptions on the central-southeast 

flank of Mauna Loa, Island of Hawai‘i, Hawaii...................................................................4

2. Radiocarbon ages of samples from the central-southeast flank of Mauna Loa 

volcano, Island of Hawai‘i, Hawaii .....................................................................................18

3. Explanation of map unit labels, colors, and patterns for lava flows and vent deposits on 

Mauna Loa, Island of Hawai‘i, Hawaii ......................................................................sheet 1

Figures

1. Map showing five subaerial volcanoes forming Island of Hawai‘i, structures on Mauna 

Loa, and 7.5-minute topographic quadrangles covering Mauna Loa.............................2
1

Mauna Loa

Mauna Loa, the largest volcano on Earth, has erupted 33 

times since written descriptions became available in 1832. Some 

eruptions began with only brief seismic unrest, while others 

followed several months to a year of increased seismicity. Once 

underway, its eruptions can produce lava flows that may reach the 

sea in less than 24 hrs, severing roads and utilities. For example, 

lava flows erupted from the Southwest Rift Zone (SWRZ) in 

1950 advanced at an average rate of 9.3 km/hr; all three lobes 

reached the ocean within approximately 24 hr (Finch and 

Macdonald, 1953). Near the eruptive vents, the flows must have 

traveled even faster. In terms of eruption frequency, pre-eruption 

warning, and rapid flow emplacement, Mauna Loa has great 

volcanic-hazard potential for the Island of Hawai‘i. Volcanic 

hazards on Mauna Loa may be anticipated, and risk substantially 

mitigated, by documenting the past activity to refine our knowledge of the hazards and by alerting the public and local government officials of our findings and their implications for hazards 

assessments and risk.

Mapping Project

The Mauna Loa project is generating detailed geologic 

maps and associated digital databases for the subaerial volcanic 

rocks of Mauna Loa (fig. 1). The temporal and spatial records 

of eruptive activity, traceable to approximately 30,000 yr 

B.P., provides a geologic framework for evaluating eruptive 

processes at large basaltic shield volcanoes and determining the 

long-term frequency and style of Mauna Loa eruptions. This 

framework can then be used as a guide for volcanic-hazard 

appraisals and land-use decisions (Trusdell, 1995).

The subaerial volcanic geology of Mauna Loa 

(fig. 1) is being mapped and digitally compiled on five 

maps at 1:50,000 scale, to show the extent of surface flows. 

Approximately 500 flows have been identified and their 

attributes compiled in a large database. This temporal and 

spatial record of eruptive activity for the last 30,000 years 

provides a geologic framework to interpret the long-term 

frequency and style of Mauna Loa eruptions. These data permit 

quantitative analysis of the distribution of eruptive products 

through time and improve evaluation of volcanic risk (Trusdell, 

1995).

Central-Southeast Flank Mauna Loa

The map of the central-southeast flank of Mauna Loa 

shows the distribution and relations of volcanic and surficial 

sedimentary deposits. It incorporates previously reported work 

published in generalized small-scale maps (Lockwood and 

Lipman, 1987; Lockwood, 1995; Wolfe and Morris, 1996a).

Mapping Methods

Geological mapping was done by using vertical aerial 

photos taken in 1977 and 1978. Extensive fieldwork required 

walking the contacts to distinguish individual flow units and 

intraflow boundaries, including gradational morphologic 

transitions between pāhoehoe and ‘a‘ā flows. Where the terrain 

and jungle obscured contacts, we created a grid pattern of 

transects. The ensuing contacts were extrapolated between 

transects from aerial photo interpretation and from geological and 

botanical inferences. Details from aerial photos were transferred 

to a 1:24,000-scale base, using a photogrammetric stereoplotter 

(Kern model PG-2), scanned, and digitized with ArcInfo software 

to create the digital database.

Reliably correlating discontinuous exposures through heavily vegetated areas is a major challenge on a volcano that consists 

entirely of compositionally similar basalt. Criteria for correlation 

include phenocryst size, morphology, and proportion; groundmass texture; vesicle shape; vesicle linings (magnesioferrite); 

flow morphology; paleomagnetic pole directions; rock chemistry; 

and varied evidence on relative and absolute ages. Paleomagnetic 

poles are an indispensable tool for making correlations between 

flows over large distances and, especially, through dense jungle. 

Individual flows typically change from pāhoehoe near the vent 

to ‘a‘ā downslope, especially for high-discharge eruptions; 

low-discharge eruptions may result in the distal emplacement of 

pāhoehoe through efficient lava-tube systems.

The pre-1868 lava flows and tephra deposits are divided 

into 15 age groups by several methods. The map is largely 

chronostratigraphic. About half the flows were dated directly 

(102 radiocarbon ages), using carbonized organic material 

recovered from beneath flows (Lockwood and Lipman, 1980). 

For undated flows, relative ages are assigned on the basis of 

rock and mineral weathering or alteration, soil and tephra 

accumulation, vegetative cover, and stratigraphic relations with 

Geologic Map of the Central-Southeast Flank of Mauna Loa 

Volcano, Island of Hawaiʻi, Hawaii

By Frank A. Trusdell and John P. Lockwood
2

Figure 1. Map showing five subaerial volcanoes forming Island of Hawai‘i, structures on Mauna Loa, and 7.5-minute 

topographic quadrangles in (shaded) and adjacent to map area.

PAC I F IC

OCEAN

–156°

20°

19°30’

19°

–155°30’ –155°

Kīlauea

Hualālai

Mauna Kea

Kohala

Mauna Loa

Northeast Rift Zone

Southwest Rift Zone

Pahala

Volcano Kilauea

Crater

Kau

Desert

Kipuka

Pakekake

Wood

Valley

Puu

Makaala

Kulani Puu

Ulaula Kokoolau

Mauna

Loa

Keaiwa

Reservoir

Punaluu

Moku‘āweoweo

Caldera

adjoining dated flows. Surface color is an indirect indicator of 

age (Lipman, 1980, table 1). Young lava flows are initially black. 

As the rock is exposed to direct sunlight and becomes increasingly weathered, its color changes from black to dull black, then 

progresses to gray, brown, tan, orange, and, finally, reddish hues. 

The longer rock is weathered, the greater the color progression. 

Lipman and Swenson (1984) used this color scheme effectively to 

tentatively classify the ages of eruptive units within limited areas. 

The utility of this technique is influenced by elevation, rainfall, 

and shielding by forest and tephra cover. Soil and tephra accumulation are also an indirect indicator of age. The thickness of tephra 

also varies with proximity to the contributing source(s).
3

Database

The digital database contains all information in the 

printed publication at 1:50,000 scale, but it is accurate to 

1:24,000 scale. A unique three-digit flow identification number 

(FID; for example, FID 831) is assigned to each flow unit 

mapped on Mauna Loa. The FIDs are unique descriptors in the 

database and are included in the Description of Map Units, as 

well as in the Correlation of Map Units. The database contains 

information on flow morphology, approximate age, exact age, 

mineralogy, data quality, unit names, rock chemistry, and any 

existing overburden type. Access the database for this map at 

https://doi.org/10.3133/sim2932B.

Acknowledgments

A great many individuals have contributed to the body 

of knowledge that has made this geologic map possible. We 

thank Meyer Rubin and Jack McGeehin and those who have 

worked in their laboratory for radiocarbon age determinations. 

Duane Champion conducted the paleomagnetic studies to test 

correlations of several geologic units. Assistants in geologic 

mapping of the central-southeast flank include Cheryl Gansecki, 

Jerome Amore, Jim Wise, Tim Tierney, and Lisa Peterson. 

People who worked as archivists of the geologic samples and 

charcoal samples include Margery Summers, Toni Thompson, 

Ramona Navarette, and Vicki Taylor. Superintendents of Hawaii 

Volcanoes National Park permitted work on the northeast rift. 

Thorough and helpful reviews of the map and text by Carl 

Thornber and Edward Wolfe resulted in many improvements in 

presentation. 

Geology

Central-Southeast Flank Mauna Loa

Although most Mauna Loa eruptions begin in the summit 

area at the 12,000-ft elevation (Lockwood and Lipman, 1987), 

the central-southeast flank has not been the source of any 

activity. All flows originated from the summit or the upper 

reaches of the Northeast Rift Zone (NERZ) or the Southwest 

Rift Zone (SWRZ), shown in figure 1. The NERZ was the 

source of eight flank eruptions since 1843. The NERZ extends 

from the 13,680-ft-high summit towards Hilo (population 

~43,000; second-largest city in State of Hawaii). The northern 

portion of the map area is built entirely on flows erupted from 

the NERZ. The SWRZ extends from the summit towards Kalae 

(South Point) at sea level. The southern portion of the map area 

is built entirely on flows erupted from the SWRZ.

The map area extends from the 10,350-ft elevation high on 

Mauna Loa’s east flank toward the Hawaii Volcanoes National 

Park and the town of Volcano (population ~2,500) in the 

northeast. At the south boundary of the map area is the town of 

Pāhala (population ~1,350). This map includes areas adjacent 

to and downslope of the NERZ and regions east of and directly 

downslope of Moku‘āweoweo, Mauna Loa’s summit caldera 

(fig. 1).

In general, the northern part of the map, about 40 percent 

of the map area, is dominated by flows from the middle and 

upper reaches of the NERZ. The southern part contains flows 

from the upper reaches of the SWRZ (~2% of the map area); 

flows are generally narrow flow lobes.

One of the most significant findings, based on detailed 

geologic mapping and dating of lava flows, is that vast sheets 

of pāhoehoe originated from the summit of the volcano. 

The sustained summit activity, which lasted for about 900 years, 

occurred between A.D. 100 and 1,000. Flows from this period 

blanketed the southeast flank and reached the sea near Punalu‘u.

Both morphologic flow types, ‘a‘ā and pāhoehoe, can 

be found. The center of the map, approximately 58 percent 

of the map area, contains flows from the summit of Mauna 

Loa. In contrast to the rift zones, the flows derived from the 

summit caldera form voluminous, broad, expansive sheets of 

pāhoehoe that cover large areas. ‘A‘ā occurs in this area but is 

inconsequential when compared to the pāhoehoe.

The geologic mapping and the radiocarbon ages indicate 

that there was a period of sustained summit activity from about 

2,000 to 1,300 yr B.P. Lava flows of this age cover more than 

75 percent of the area directly downslope from the summit. 

There are a few kīpuka of older flows, but they are limited in 

number and extent.

Volcanic Deposits

Flows

The map encompasses 506 km2 of the southeast flank (fig. 1) 

of Mauna Loa from 10,350-ft elevation to sea level. It shows the 

distribution of eruptive units separated into 15 age groups ranging

from a period greater than 50,000 yr B.P. to A.D. 1984.

Pāhoehoe, which covers more than 60% of the map area,

is characterized by bulbous, smooth, and ropy surfaces, and the

general topography can be described as hummocky. Lava tubes

are common features in pāhoehoe flows. Most ‘a‘ā flows also

start as pāhoehoe flow types near the vents and transition to ‘a‘ā

downslope.

‘A‘ā flows are generally thicker and form broader units than

pāhoehoe flows. ‘A‘ā flows are characterized by rubbly and (or)

clinkery surfaces with a rough texture; they are typically 3 to 15 m

thick.

Effusion rates and slope influence lava morphology. 

High effusion rates, combined with steep slopes, usually 

generate ‘a‘ā. Moderate to low effusion rates typically 

produce pāhoehoe. Not surprisingly, ‘a‘ā is abundant in the 

region, which has the highest effusion rates and some of the 

steepest slopes of any sector of Mauna Loa (Trusdell, 1995). 

The relation between high effusion rates and steep slopes has 

momentous implications for volcanic hazards and flow-advance 

rates. Historical flows from the SWRZ have reached the sea in a 

matter of hours to days (see individual eruption narratives in the 

Age Group 0 section for specific details).
4

entered stream channels above Hilo and appeared to accelerate. 

By August 10, 1881, all forward progress ceased. 

Age Group 1 (pre-A.D. 1843–1,000 yr B.P.)

Spatter and flows are typically slightly weathered and have 

negligible overlying soil or tephra except in forested areas. Surficial black glass is common. Eight flows have radiocarbon ages. 

All flows of Age Group 1 originate from the NERZ. Eruptions 

from this period cover approximately 20 percent of the map area.

Age Group 2 (1,000–2,000 yr B.P.)

Spatter and flows typically have some overlying soil or 

tephra at lower elevations, and any surficial glass shows slight 

mechanical degradation and color lightening to gray hues. 

Thirteen of twenty-five flows have radiocarbon ages. Eruptions 

from this period cover nearly 48.5 percent of the map area.

Age Group 3 (2,000–3,000 yr B.P.)

Spatter and flows are mildly weathered, and surficial glass 

is locally preserved. Four of ten flows have radiocarbon ages. 

Eruptions from this period cover 4.7 percent of the map area.

Age Group 4 (3,000–4,000 yr B.P.)

Spatter and flows are moderately weathered, and surficial 

glass is preserved only in protected places. One of twelve 

flows has a radiocarbon age. Eruptions from this period cover 

2.4 percent of the map area.

Age Group 5 (4,000–5,000 yr B.P.)

Spatter and flows are moderately weathered, surficial 

glass is rare, and upper surfaces have moderate mechanical 

degradation. These flows commonly have as much as 0.4 m 

of overlying soil or ash when in close proximity to Kīlauea 

Volcano. One flow of eight has a radiocarbon age. Eruptions 

from this period cover 1.9 percent of the map area.

Age Group 6 (5,000–6,000 yr B.P.)

These rocks are increasingly weathered, surficial glass is 

gone, and upper surfaces have open vesicle texture. Units are 

typically covered with 0.2–0.3 m of ash or soil, especially at lower 

elevations. Eruptions from this period cover much less than 1 

percent of the map area.

Vesicles are present in both pāhoehoe and ‘a‘ā flows. In 

‘a‘ā flows, vesicles are generally fewer in number and volume 

(<35%), irregularly distributed, commonly deformed and 

subangular in shape, and larger in size than in pāhoehoe flows. 

In contrast, vesicles in pāhoehoe flows are smaller, more abundant, and voluminous (40–60%), moderately distributed to well 

distributed, and spherical to subrounded in form.

Age Groups

The age groups are arbitrary boundaries created by the 

authors. They are broken down into 1,000-year intervals until 

the latter age groups. The larger age groups represent time 

periods greater than 1,000 years. The age groups are defined 

based on radiocarbon years. Unless the flows are dated, the 

reliability of age determinations decreases with increasing age.

Age Group 0 (Historical period: A.D. 1843 and younger)

Lava erupted from A.D. 1880 to 1984 covers 1.1 percent 

of the map area (table 1). Eruptions occurred in 1880–81 and 

1984. Soil or ash cover is absent except in forested areas, and 

surficial glass is common.

A.D. 1984—The 1984 eruption began on March 25

and continued for 22 days. It was Mauna Loa's fifth longest 

historical NERZ eruption; the erupted volume is 220 x 106 m3

(Lockwood and others, 1985). Much of the lava is ‘a‘ā. The 

vents were distributed along a 15-km segment of the NERZ 

between 9,350- and 12,400-ft elevation. Most fissures are north 

of the map area at higher elevations. The main fissure is located 

at approximately 9,600-ft elevation. The fissure that fed the 

flow in the map area is located at 11,185-ft elevation. The flows 

from this eruption came within 17 km of Kīlauea.

A.D. 1880–81—The eruption of 1880–1881 began on

May 1, when a small, short-lived eruption at Mauna Loa's 

summit heralded the beginning of an eruptive sequence that 

was followed 6 months later by a voluminous flank eruption. 

This flank eruption would eventually threaten the Hilo area. 

The flank phase of the eruption began on November 5, 1880. 

The outbreak was located at the 11,000-ft elevation, about 

1.5 km above Pu‘u‘ula‘ula. High lava fountains fed an ‘a‘ā 

flow that moved swiftly down the north flank (north of the map 

area). Another branch of ‘a‘ā flowed southeast, stopping within 

3.5 km of Kīlauea Volcano. By early June, the flow was within 

8 km of Hilo, and concern mounted. On June 26, 1881, the flow 

Year Eruption begins

(month/day)

Summit 

activity 

(days)

Flank 

activity 

(days)

Eruptive area of 

volcano

Area covered 

(km2

)

Volume 

(km3)

Error in estimate

(percent)

Closest reach 

to Kīlauea 

(km)

1984 March 25 <1 22 S, NE 48 0.220 ±20 17.0

1880 November 5 0 280 NE, SW 51 0.130 ±20 to 40 3.5

Total 99 km2 0.35 km3

Table 1. Summary statistics of historical (after A.D. 1843) eruptions on the central-southeast flank of Mauna Loa, Island of Hawai‘i, 

Hawaii.

[S, Summit; NE, Northeast Rift Zone; SW, Southwest Rift Zone]
5

Age Group 7 (6,000–7,000 yr B.P.; not in map area)

Flows with dates of 6,000–7,000 radiocarbon yr B.P. were 

not identified within the map area. With so many undated flows, 

a few could fall into this age category. The absence of dates in 

this range suggests that eruptive activity may have been limited to 

the summit (lava lake activity) or the volcano's submarine flanks 

during this time interval (Lockwood, 1995).

Age Group 8 (7,000–8,000 yr B.P.)

The flows are weathered; upper surfaces have open-vesicle 

texture and are broken, and orange surfaces occur at higher elevations. Ash has accumulated in low areas. This age group is represented by a single dated flow. Eruptions from this period cover 2.1 

percent of the map area.

Age Group 9 (8,000–9,000 yr B.P.)

The flows are deeply weathered, showing red-orange surfaces at higher elevations; mechanical disintegration of upper surfaces is almost complete. Ash has accumulated in low areas. Two 

of five flows have radiocarbon ages. Eruptions from this period 

cover 2.7 percent of the map area.

Age Group 10 (9,000–10,000 yr B.P.)

These flows and all older age groups are found only at the 

southeastern portion of the map area; they have been buried by 

younger flows closer to eruptive vents. Ash and soil fill low-lying 

areas; accumulations of as much as 0.5–1 m are common. Surface 

color approaches red. Three of six flows have radiocarbon ages. 

Eruptions from this period cover slightly more than 3 percent of 

the map area.

Age Group 11 (10,000–15,000 yr B.P.)

These flows have few original surfaces left. Upper surfaces 

are commonly stained red orange, probably due to hydration of 

glass. In the wet, windward regions, the rock is soft, and hammer 

impacts often leave a divot. Olivine is altered, yellow, and (or) 

brown green and looks slightly flaky. Units of this age have 1–3 m 

of soil or ash cover. Partly altered groundmass is often a dull gray 

and appears cryptocrystalline. Two of four flows have radiocarbon 

ages. Eruptions from this period cover 0.5 percent of the map area.

Age Group 12 (15,000–20,000 yr B.P.; not in map area)

Flows with dates of 15,000–20,000 were not identified 

within the map area. These flows have no original surfaces left. 

Upper surfaces are commonly stained red orange, probably due 

to hydration of glass. In the wet, windward regions, the rock 

is yielding and mushy; hydrated glass turns to clay. Olivine 

appears flaky and (or) cloudy and mostly altered. Units of this 

age have 2–4 m of soil and ash cover. Groundmass is altered 

and lined with alteration products (such as limonite).

Age Group 13 (20,000–30,000 yr B.P.)

These flows are exposed in drainages and include the 

only surface exposures of Pāhala Ash (unit pa) southeast of 

Nā‘ālehu, at the coast near Kāhilipali Nui, and at the crest of the 

Kahuku Pali. The flows have no remaining original surfaces. 

Boundaries between individual flows are blurred. In the wet, 

windward regions, the rock is mushy; olivine phenocrysts are 

altered. Four units have radiocarbon ages. Eruptions from this 

period cover much less than 1 percent of the map area.

Age Group 14 (30,000–100,000 yr B.P.; not in map area)

These flows are exposed in fault scarps, sea cliffs, and 

drainages around Pāhala. Flows are commonly overlain by 

as much as 6 m of ash. Flows have lost all original surfaces, 

and boundaries between individual flows are blurred. In wet, 

windward regions, the rock is mushy; olivine phenocrysts are 

mostly altered and generally soft. Eruptions from this period 

cover less about 0.4 percent of the map area.

Age Group 15 (>100,000 yr B.P.)

Flows with dates of >100,000 yr B.P. were identified 

within the map area around Wood Valley. These flows are 

exposed in valley walls. The unit represents the oldest exposed 

rocks on Mauna Loa. These rocks are commonly overlain by as 

much as 6 m of ash and have no remaining original surfaces.

Surficial Sedimentary Deposits

Deposits were too small and transient to map. They consist 

chiefly of colluvial and alluvial deposits of basalt clasts and 

pebble- to cobble-sized gravel in drainages that occur locally 

within portions of the map area. We also include under this 

category unconsolidated sand along the coast.

Volcanic Ash

Pāhala Ash

Pāhala Ash includes beds of fallout and surge deposits that 

represent accumulation of deposits from numerous eruptions. 

Deposits include glassy ash and lapilli, now mostly altered to 

clay, crystals, and lithic fragments. Phenocryst abundance is 

difficult to estimate, owing to chemical decomposition, but 

ranges from aphanitic to moderately porphyritic, with as much 

as 8 percent olivine and fewer plagioclase phenocrysts. It is 

found chiefly in all quadrangles and in adjacent upslope areas, 

where it overlies lava flows ranging in age from 31,000 to 

2,000 yr B.P.

There are two main subdivisions in this group: southern 

tephra (unit ts) and Pāhala Ash (unit pa). Southern tephra 

comprises beds of ashfall deposits in the map area. The source 

of the ashes is unknown but is considered to be primarily from 

Kīlauea Volcano, with likely contributions from Mauna Loa 

(Easton, 1987). All ash deposits ≤10,000 yr B.P. are included in 

this category and cover nearly 12.8 percent of the map area.

The term “Pāhala Ash,” named for the town Pāhala, was 

used with reference to ash deposits found along the northeast 

rift zone of Mauna Loa, northeast Kīlauea Volcano, and south 

and southwest of Kīlauea’s summit, including the eastern flank 
6

of Mauna Loa. The bulk of the ash is presumed to be from 

Kīlauea, although Mauna Loa cannot be excluded as a source.

Pāhala Ash was described by Stone (1926), Stearns and 

Clark (1930), Wentworth (1938), Stearns and Macdonald 

(1946), Fraser (1960), Walker (1969), and Easton (1987). The 

term eventually came to be used for ashes from Kohala to Kalae 

at South Point. According to Easton (1987), Wolfe (verbal 

commun., 1986) determined that the ash deposits of Kohala, 

Waimea, Hāmākua, and North Hilo were derived locally and 

are chemically distinct from ashes near Kīlauea and on the east 

flank of Mauna Loa.

Wentworth (1938) and Stearns and Macdonald (1946) 

describe several sections of Pāhala Ash, yet, a type section 

was not identified. Easton (1987) proposed two well-exposed 

sections on the south flank of Kīlauea Volcano for the type 

locality of the Pāhala Ash.

The ash is a mixture of yellow-brown palagonite, rare 

vitric shards, Pele’s hair, pumice, and olivine phenocrysts. It is 

derived from airfall deposits, weathered and reworked ash, and 

sediments. The ash is composed of mostly sand and silt-sized 

fractions. Ancient soil horizons are present in some localities.

The appearance of the ash is greatly influenced by climate. 

In dry areas, it is friable, in places compact, but it is mostly 

sandy, loose, and dusty. In higher-rainfall areas, the ash appears 

clay-like. The ash deposits from Ka‘alu‘alu to Kalae or South 

Point appear to be loess, reworked and redeposited by wind.

All ashes in the map area that are less than, and equal to, 

late Pleistocene (<16,000 yr B.P.) are incorporated into unit ts, 

which identifies a mostly Holocene ash deposit of sufficient 

thickness to mask the underlying flow(s) or the extent of the 

flow(s) cannot be mapped with a reasonable degree of certainty. 

In other places, where we are able to map ash-covered flows, 

<16,000 yr B.P. in age, with a high degree of certainty (see database for contact certainty), we chose to use a plus pattern. The 

overlying ashes are grouped with unit ts.

Our mapping demonstrates—and previous investigators 

noted (Stearns and Macdonald, 1946; Easton, 1987)—that 

the Pāhala Ash was a catch-all for all ash units from northeast 

Kīlauea Volcano, across Kīlauea’s south flank, extending over 

Mauna Loa to (at least) Kalae to Kahuku Pali. This included 

ashes of all ages (0.2–25 ka; Stearns and Macdonald, 1946). 

The periodicity with respect to Pāhala Ash production was more 

infrequent than was previously recognized.

We are able to show that there have been at least eight 

ash events, where lava flows separate the younger ash layers 

(unit ts). Most of the individual ash horizons have not been 

studied well enough to be used as marker beds over a wide 

geographic area. We concur with previous investigators that the 

most likely source is Kīlauea, although Mauna Loa cannot be 

excluded as a source.

In order for Pāhala Ash to be recognized as a stratigraphic 

marker, its horizon needs to be recognizable over a large 

geographic region. Easton (1987) proposed a more restrictive 

age range of 25–10 ka for Pāhala Ash. Our preference would 

be to restrict the Pāhala Ash age even further, to approximately 

31–16 ka, and possibly older, thereby providing a constraining 

period of time within which substantial ash accumulation 

occurred and is preserved, in places, on the flanks of Mauna 

Loa. The accumulated ash can then be used as a stratigraphic 

marker across a wide region. Unfortunately, this means that 

most type sections can only be found in drainages, arroyos, sea 

cliffs, and on top of Nīnole Hills above Punalu‘u.

Radiocarbon Data

Radiocarbon is obtained from under flow margins and 

usually dates the surface flow. This map includes some ages 

obtained from a vertical section (for example from a waterfall). 

Flows that are dated, in sections, from charcoal are represented 

by a solid black square on the map. In a few instances, we were 

able to obtain charcoal under the surface unit, but not at the 

contact between adjacent flows. The symbol is found inboard 

of the contact. In a few of these cases, heavy equipment broke 

through the flow (at a quarry), and we retrieved charcoal. In 

other instances, we obtained charcoal from arroyos, and the 

underlying outcrops were less than 5 m2. Due to the limited 

exposure, we were not able to adequately characterize these 

units, and the map units were tiny; we do not show these units.

Table 2 reports 102 radiocarbon ages from 46 lava flows 

(Kelley, 1979; Kelley and others, 1979; Rubin and others, 1987; 

Buchanan-Banks and others, 1989; Buchanan-Banks, 1993; 

this study). Many are conventional ages determined at the U.S. 

Geological Survey (USGS) laboratory in Reston, Virginia. 

Thirty-six Accelerator Mass Spectrometer (AMS) ages were 

analyzed by USGS and other laboratories. For eruptive units 

at more locations, each age is weighted by the inverse of its 

variance to yield a mean age (Taylor, 1982).

All ages were calibrated to calendar years, using the 

CALIB 6.0 Radiocarbon Calibration Program (Stuiver and 

others, 2005). The calibrated age ranges in table 2 encompass 

the calendar years possible for a given radiocarbon age at two 

standard deviations; however, all ages shown on the map are 

radiocarbon yr B.P. Symbols in table 2 indicate reliability of age 

for stratigraphic interpretations. Rejected ages are reported in 

the appendix.

Fault Systems

The system of normal faults, which occurs on the southeast 

flank of the volcano, are the Ka‘ōiki-Honu‘apo Fault System. 

Faults shown on the map were adapted from Wolfe and Morris 

(1996a). All faults within the map area are inactive and are 

draped by unfaulted, younger flows as old as 9,500 yr B.P. The 

concealed fault scarps are as much as 100 m high and traceable 

for as much as 10 km in an east-northeast direction.

In addition to the concealed faults on the southeast flank, 

there is a historically active tectonic zone. This area, known as 

the Ka‘ōiki Fault Zone, is in the epicentral region for some recent 

large tectonic earthquakes. The Ka‘ōiki Fault Zone has been 

active as recently as 1983 and prior to that in 1974 and 1962. 

In 1983, there was a 6.6 ML earthquake on the southeast flank 

of Mauna Loa and there was discernible movement along this 

fault system. Ground rupturing took place, and displacements 

measured as large as 1.5 m in 1983 and as large as 0.5 m in 

1974. Unlike the concealed faults of the Ka‘ōiki-Honu‘apo Fault 
7

System, which are buried normal faults, ground breakage in the 

Ka‘ōiki Fault Zone is characterized by recent, left-stepping, en 

echelon ground cracks created by strike-slip motion along a fault 

system that strikes N. 40–50° E. (Jackson and others, 1992).

In the Wood Valley quadrangle, there are two graben that 

extend upslope. One graben cuts units p2e11 and p3e4; the 

second is found entirely within unit p3e4. Faults shown in the 

map area are adopted from Wolfe and Morris (1996a).

DESCRIPTION OF MAP UNITS

[Small areas on the printed or plotted map are not labeled, to avoid obscuring data; use unit color or the database (https://

doi.org/10.3133/sim2932B) for unit identification. The simplified map unit label is not unique and provides quick access 

to flow morphology, flow age group, phenocryst mineralogy, and flow number in an age group (table 3, sheet 1); this nonunique unit label may be used for an entirely different unit on a different flank of Mauna Loa. We use the term "phenocryst" for any mineral ≥1 mm in maximum diameter. Pyroxene is not an abundant phenocryst in Mauna Loa lava flows

and, therefore, it is not included in phenocryst mineralogy. Multiple labels for a unit are listed with the most abundant

lithology first. In addition to the map unit label, a unique, three-digit, flow identification number (FID; for example, FID

831) is assigned to each mapped flow unit to facilitate use of the database; therefore, the FID is essential as a unique

descriptor for unit identification in the database. No Age Group 7, 12, or 14 units were identified in the map area]

SEDIMENTARY DEPOSITS

mf Mudflow deposits of A.D. 1868 (Holocene)—In A.D. 1868, a large destructive earthquake caused 

a landslide in the back of Wood Valley and south of Ipu‘u Ridge. Rock lubricated by wet 

ash tumbled down from the hillside. Stearns and Macdonald (1946) originally mapped the 

mudflow, which we have included on our map. The original extent of the mudflow is no longer 

evident, because sugar cane companies spread out the deposits to enhance productivity 

ls Landslide deposits (Holocene)—Landslides of unknown age, including some of the 1868 mudflow, 

are shown on the map in the region of Wood Valley. In recent mapping, we were only confident 

of landslide deposits at the foot of the valley walls and short distances downslope. The bulk of 

the deposits were spread out by sugar cane companies as media to grow cane

VOLCANIC DEPOSITS

LAVA FLOWS AND VENT DEPOSITS

Ka‘ū Basalt

The Ka‘ū Basalt includes historic and prehistoric members. The prehistoric units range in age from pre-A.D. 

1843 to 30,000 yr B.P. The Ka‘ū Basalt consists of tholeiitic basalt, vent deposits, and lava flows. The flows are mostly 

aphanitic and some have variable amounts of olivine and plagioclase phenocrysts. Pyroxene is rare in hand specimen. 

All but one of the map units are members of the Ka‘ū Basalt.

Age Group 0 (A.D. 1843 and younger; Holocene)

a0a1 A.D. 1984 flow—Aphanitic ‘a‘ā, with <1% olivine phenocrysts 1–2 mm in size. Vents were distributed

along 15-km segment of NERZ between 9,350- and 12,400-ft elev. Most fissures are north and 

west of map area some at higher elevations. A flow from this eruption enters the north margin of 

the map area. The eruptive fissure that fed this flow is located at the 11,185-ft elev. FID 783

a0b2 A.D. 1880–81 flow—Flow is fresh and glassy, with 1–3% clear olivine phenocrysts and abundant,

inconspicuous plagioclase microphenocrysts. An ‘a‘ā flow enters from the north edge of the 

map and extends ~13 km in a southeasterly direction diagonally across the map. FID 787

Age Group 1 (pre-A.D. 1843–1,000 yr B.P.; Holocene)

a1g1 Ke‘āmuku Kīpukakēkake flow—Dense, fine-grained, ‘a‘ā in Kilauea Crater, Kau Desert, and 

Kipuka Pakekake quadrangles. Groundmass is sparkly, dark, and feldspathic. Small olivine 

phenocrysts (<1%) are widely scattered; 1–2% plagioclase is present as fine laths. Age, 288±36 

radiocarbon yr B.P. FID 800
8

m1k2

p1k5

m1a3

m2i3

p1k2, a1k2, Kīpukamauna‘iu flow—Pāhoehoe and ‘a‘ā, in contact with the lava flow of A.D. 1880, in Kipuka 

Pakekake quadrangle. Contains dense, well-crystallized, feldspathic groundmass. Surface is 

medium gray to black. Flow tops, locally glassy, are mostly weathered; surface glass is broken 

up. Flow contains 0–1% small olivine phenocrysts and 1–8% anhedral laths and clots of 

plagioclase, commonly intergrown with olivine. Vesicles are subrounded, commonly distorted, 

and may be lined with magnesioferrite. Age, 311±25 radiocarbon yr B.P. FID 801

p1a3, a1a3 Ke A Po‘omoku Lava Flow—Massive pāhoehoe and ‘a‘ā that flooded Mauna Loa’s flank northeast of the caldera and southeast of the rift zone in northwestern Kipuka Pakekake quadrangle. 

Eruptive fissures of this eruption extend into the NERZ and are found outside of the map area 

to the northwest. Contains <1% olivine phenocrysts in medium-gray, fine-grained feldspathic 

groundmass. Age, 475±41 radiocarbon yr B.P. FID 274

p1g4 Ke‘āmuku Kīpukakulalio flow—Dense, dark-gray, nearly aphanitic pāhoehoe in northeastern Kipuka 

Pakekake and northwestern Kilauea Crater quadrangles. Flow contains <1%, widely scattered 

olivine phenocrysts and 2% plagioclase phenocrysts. Age, 569±53 radiocarbon yr B.P. FID 802

a1k5, m1k5, Ke‘āmuku Kīpukakulalio east flow—Tube-fed pāhoehoe with some ‘a‘ā, in Kipuka Pakekake 

quadrangle. Glass is fresh where protected from mechanical weathering. Contains 2–6% olivine 

phenocrysts and from 5–10% plagioclase as laths, clumps, and intergrowths with olivine. 

Vesicles are mostly rounded and coated with magnesioferrite. Tree molds are exposed along 

Pu‘uʻōʻō Volcano Trail where not covered by ash. Abundant charcoal samples can be found 

where this unit overlies a5b7 (FID 870). Age, 575±38 radiocarbon yr B.P. FID 799

p1l6, a1l6 Keauhou Ranch flow—Large tube-fed pāhoehoe with minor ‘a‘ā north of Kīpukapuaulu, on 

Keauhou Ranch in central Kilauea Crater quadrangle. The 6–20% olivine forms phenocrysts 

and microphenocrysts; 4–6% plagioclase mostly microphenocrysts and groundmass. 

Age, 760±70 radiocarbon yr B.P. FID 833

a1b7, p1b7 Flow northeast of A.D. 1880 lobe—Mixed ‘a‘ā and pāhoehoe flows in northeastern Kipuka 

Pakekake quadrangle. Contains 4% inconspicuous round olivine phenocrysts. Age, 780±70 

radiocarbon yr B.P. FID 840

p1e8, a1e8 Pu‘uwahi picrite flow—Dense picrite in northeastern Kipuka Pakekake and central Kilauea Crater 

quadrangles. Pāhoehoe and ‘a‘ā with a medium-gray groundmass, containing 10–20% clear, 

fresh olivine phenocrysts as much as 6 mm across. Weathered surfaces are orange brown, with 

protruding olivine minerals. Age, 955±24 radiocarbon yr B.P. FID 837

a1i9, p1i9 Ke‘āmuku Kīpukakulalio west flow—Both ‘a‘ā and pāhoehoe in northwestern Kilauea Crater 

quadrangle. Flow contains 3–8% subhedral, sugary olivine phenocrysts and 0–2% plagioclase 

phenocrysts. Vesicles are subrounded to elongate and may be magnesioferrite lined. FID 838

Age Group 2 (1,000–2,000 yr B.P.; Holocene)

a2g1 Flow 300—‘A‘ā flow in northwest quadrant of Kipuka Pakekake quadrangle. Flow contains 1–2% 

olivine microphenocrysts and abundant groundmass plagioclase to 2% as phenocrysts. The 

groundmass is dark gray and dense, with abundant plagioclase microlites. Unit overlies p2i3

(FID 298). FID 300

p2b2 West Wood Valley flow—Flow that forms floor of western side of Wood Valley. A spongy tube-fed 

pāhoehoe has 0–5% olivine phenocrysts in light-gray diktytaxitic groundmass. Flow is covered 

by variable amounts of soil ash that can be as thick as 1.5 m. Primary surfaces with black glass 

common; glass usually found in protected spots on surface and commonplace on base. Age, 

1,281±66 radiocarbon yr B.P. Unit overlies p2b23 and p2b24 (FIDs 292 and 294). FID 293

p2i3, a2i3, Pahuamimi flow—Major unit from summit region of Mauna Loa. Flow traverses Kipuka Pakekake 

from northwest to southeast in central and northeastern portions of the quadrangle. Flow is 

most common as tube-fed pāhoehoe. Tumuli are common, as are areas containing slabby 

pāhoehoe and fluid ‘a‘ā. Contains 5% plagioclase as blades and commonly intergrown 

with olivine. Unit contains 2% olivine phenocrysts and microphenocrysts. Age, 1,293±27 

radiocarbon yr B.P. Unit overlies a2k13 (FID 347). FID 298

p2a4, a2a4 Keakapulu Flat flow—Young-looking tube-fed pāhoehoe unit in north-central Wood Valley 

and southwestern Kipuka Pakekake quadrangles. Unit has 3–8% inconspicuous olivine 

microphenocrysts. Due to their small size, the olivine could be easily overlooked. The groundmass is well crystallized and feldspathic with obvious plagioclase microlites. Unit is covered 

with as much as 30 cm of ash. Age, 1,428±38 radiocarbon yr B.P. FID 297

p2i5, a2i5 Kapāpala flow—Tube-fed pāhoehoe in central Wood Valley unit originated from summit. 

Flow contains 3–8% olivine phenocrysts and differs from its neighbors in that it has 2–3% 
9

m2e8

plagioclase. Upper surfaces usually orange stained and may be topped by a 6–8 mm glassy rind. 

Flow is characterized by hummocky terrain. Flow is often overlain by 10–50 cm of ash. Age, 

1,469±32 radiocarbon yr B.P. FID 344

p2c6 Kilohana flow—Tube-fed pāhoehoe found in central Wood Valley quadrangle. This flow is distinctive 

in that the olivine has two habits: laths and equant phenocrysts. Flow contains 5–15% olivine phenocrysts and microphenocrysts. The groundmass is well crystallized and feldspathic. Flow has little 

to no ash cover. Age, 1,507±24 radiocarbon yr B.P. Unit overlies p2c25 (FID 340). FID 301

p2f7 Waimuku flow—Large tube-fed pāhoehoe in Wood Valley and Pahala quadrangles. This unit is 

distinctive in that the flow contains olivine with two habits: equant phenocrysts and laths. Flow 

has variable amounts of olivine, at 3–20%; flow tops are black and glassy. The groundmass is 

light gray, well crystallized, microcrystalline. Flow is covered by 10–50 cm of ash in places. 

Age, 1,511±24 radiocarbon yr B.P. Unit is overlain by p2b2 (FID 293). In addition, it overlies 

p2f9, p2b10, and p2b15 (FIDs 288, 290, and 336). FID 289

p2e8, a2e8, Pu‘u‘ele‘ele flow—Expansive pāhoehoe flow field with minor ‘a‘ā and ash mantle, found in 

southwestern Kipuka Pakekake and northeastern Wood Valley quadrangles. Flow is distinctive 

in that olivines protrude through the glassy surface giving the flow a knobby appearance. 

Flow contains ~20% olivine and as much as 5% plagioclase. The olivines range in size from 

4–8 mm and are clear and sugary. Subhedral plagioclase occurs as anhedral phenocrysts and 

microphenocrysts to 2 mm and is commonly intergrown with olivine. Vesicles are subrounded 

and magnesioferrite lined. Age, 1,530±37 radiocarbon yr B.P. FID 346

p2f9 Ka‘ala‘ala Gulch flow—Large tube-fed pāhoehoe in western Wood Valley and Ka‘ala‘ala Gulch. 

This extensive pāhoehoe is one of many similar flows of summit origin in this region. The unit 

contains 2–8% olivine phenocrysts and microphenocrysts in a diktytaxitic groundmass. The 

flow is covered by 10–50 cm of ash in places. Age, 1,574±25 radiocarbon yr B.P. FID 288

p2b10 Kapāpala Ranch flow—Tube-fed pāhoehoe, in Wood Valley quadrangle, contains 1–5% olivine. Also, 

found at the site of Kapāpala Ranch headquarters. Flow is covered with a veneer of ash as thick as 

0.5 m. In low slope areas, tumuli and hummocky terrain dominate flow character. Flow tops orange 

stained with original flow surfaces common. Black vitreous glass only preserved in folds and creases 

on upper surfaces and glass is common on flow bottom. Age, 1,622±23 radiocarbon yr B.P. FID 290

a2k11, p2k11 Upper Waiākea flow—Mixed pāhoehoe and ‘a‘ā flows along the north edge, and in the center of, 

Kilauea Crater quadrangle. Contains 0–2% olivine phenocrysts, commonly as intergrowths 

with plagioclase, and 5–12% very fine plagioclase as laths and blebs. Vesicles are subrounded, 

elongate, and commonly magnesioferrite lined. ‘A‘ā is crumbly and weathered to a yellow 

orange. The flow is covered with a thin to thick layer of soil and ash; consequently, outcrops 

range from abundant to rare. This eruption sent flows over both sides of the rift zone, though 

the bulk of the lava flowed to the northeast. Age, 1,638±32 radiocarbon yr B.P. FID 864

a2a12, p2a12 Flow 841—Aphanitic ‘a‘ā, with minor pāhoehoe, found in the central portion of Kipuka Pakekake 

quadrangle. The ‘a‘ā is dense, fine-grained, and feldspathic. Flow is covered by deep soil. Unit 

overlies p2e14 (FID 343). FID 841

a2k13, p2k13 Nāpu‘ukūlua Lava Flow—‘A‘ā flow 10–12 m thick with distinctive mineralogy found in northwest 

quadrant of Kipuka Pakekake quadrangle. Contains 6–8% plagioclase laths and ~1% olivine 

phenocrysts in a dense medium-gray groundmass. Surface color is chocolate brown; minor 

yellow ash deposited in low areas. Unit overlies p2e14 (FID 343). FID 347

p2e14, a2e14 Kauhiuhi flow—Major tube-fed olivine-rich pāhoehoe at junction of Kilauea, Kipuka Pakekake, 

and Wood Valley quadrangles. This distinctive olivine-rich pāhoehoe has ~20–25% clear green 

phenocrysts in a dull gray cryptocrystalline groundmass. The upper flow surface appears to 

be knobby or warty owing to olivine protruding through the surface glass. The basaltic glass 

is common but mostly eroded away. Age, 1,640±150 radiocarbon yr B.P. Unit is overlain by 

a2a12 and a2k13 (FIDs 841, 347). FID 343

p2b15 East Wood Valley flow—Tube-fed pāhoehoe flow, which traverses the eastern portion of 

Wood Valley. Flow contains 1–3% olivine phenocrysts in a light-gray, well-crystallized 

plagioclase microlite-rich groundmass. Covered with variable amounts of ash, 0–1.5 m thick. 

Age, 1,708±50 radiocarbon yr B.P. Unit is overlain by p2b2 and p2f7 (FIDs 293, 289). FID 

336

p2b16 Moa‘ula flow—Young-looking spongy pāhoehoe flow between Hi‘onamoa and Moa‘ula Gulches in 

Pahala quadrangle. Flow originates from the Southwest Rift Zone of Mauna Loa. The pāhoehoe 

has 0–2% olivine in a well-crystallized groundmass. The flow tops are black and glassy. Flow 

overlain by ash in low-lying areas. Age, 1,824±19 radiocarbon yr B.P. FID 540
10

m2a18

a3e4

p2j17, a2j17 Flow 350—Pāhoehoe in the northwest corner of Kipuka Pakekake quadrangle. Variable olivine 

mineralogy ~8–20%, subhedral, blades and phenocrysts. Olivines are dull, light green in color, 

inconspicuous, and range in size from 0.5–2.5 mm. Anhedral clots of plagioclase and olivine 

are common at 2–3%. The groundmass is medium gray and feldspathic. The surface color is tan 

gray; ash cover is thin at 0–0.14 m and concentrated in low-lying areas. Unit overlies a2a18

(FID 349). FID 350

a2a18, p2a18, Kauhiuhi Maluikeao flow—Aphyric pāhoehoe with <1% fine olivine phenocrysts in a diktytaxitic, 

vesicular groundmass. Groundmass is bluish gray, dense, and occasionally feldspathic. Upper 

surfaces in places weathered to yellow orange; otherwise, color is tan gray. Flow is found in 

northwest corner of Kipuka Pakekake quadrangle. Age, 1,910±120 radiocarbon yr B.P. Unit is 

overlain by p2j17 (FID 350). FID 349

a2a19, p2a19 Flow 989—Aphanitic flow located in center of adjoining boundaries of Kilauea Crater and Kipuka 

Pakekake quadrangles. This pāhoehoe has a well-crystallized groundmass that contains 

plagioclase microlites. Flow is blanketed by ~20 cm of ash. Surface color is orange gray and 

original primary surface is almost nonexistent. Unit overlies p2k20 (FID 893). FID 989

a2k20, p2k20 Kīpukalō‘ihi flow—Blocky ‘a‘ā kīpuka east and southwest of A.D. 1880. Distal end of flow is 

20–25 m thick near the boundaries of Kilauea Crater and Kipuka Pakekake quadrangles. Flow 

contains 4–10% plagioclase phenocrysts and 1–3% olivine phenocrysts in a medium-gray 

groundmass. Olivine commonly intergrown with plagioclase. Flow covered by a minor amount 

of ash. Unit overlies p2g22 (FID 883). FID 893

a2k21, p2k21 Flow 900—‘A‘ā flow along the west border of Kilauea Crater quadrangle. Flow contains 

5% plagioclase laths as glomerocrysts and 2% olivine phenocrysts intergrown with plagioclase. 

The flow exhibits pāhoehoe-like character in places, with slabby plates and toothpaste-like 

morphologies. Unit overlies p2g22 (FID 883). FID 900

p2g22, a2g22 Upper Strip Road flow—Extensive pāhoehoe and related tube system, characterized by bulbous 

toes, south of Nāpu‘ukūlua in northwestern Kipuka Pakekake and Kilauea Crater quadrangles. 

Contains <1% olivine phenocrysts and ~2% plagioclase as microphenocrysts and phenocrysts. 

Vesicles are spherical to subrounded. Age, 1,993±43 radiocarbon yr B.P. Unit is overlain by 

a2k20 and a2k21 (FIDs 893, 900). FID 883

p2b23 Pi‘ikea flow—Pāhoehoe flows that form southwest valley floor and ridge of Wood Valley. Flow 

comprises multiply bedded pāhoehoe units containing 1–5% inconspicuous olivine phenocrysts 

in a light-gray microcrystalline groundmass. Unit is overlain by p2b2 (FID 293). FID 292

p2b24 Keaīwa Gulch flow—Another tube-fed pāhoehoe found along Ka‘ala‘ala Gulch in Wood 

Valley quadrangle. Flow contains 1–5% olivine phenocrysts and 0–1% plagioclase in a 

microcrystalline, gray, feldspathic groundmass. Flow is covered by 0.5–1.5 m of ash. Unit is 

overlain by p2b2 (FID 293). FID 294

p2c25 Flow 340—Pāhoehoe near highway along Pāhala-Volcano road in Wood Valley quadrangle. 

Pāhoehoe contains 5–7% olivine phenocrysts in a light-gray microcrystalline groundmass. Flow 

surface is orange-stained glassy top. The flow is covered by 0.2–1 m of ash. Unit is surrounded 

by p2c6 (FID 301) at the Kīlauea Volcano contact. FID 340

Age Group 3 (2,000–3,000 yr B.P.; Holocene)

a3a1 Red Cone flow—‘A‘ā flow of Keaīwa Gulch with 0–1% olivine phenocrysts in a well-crystallized 

feldspathic groundmass. Prominent flow, north and east of Pāhala town, planted in eucalyptus 

and macadamia. Unit is locally mantled by ash and is overlain by pāhoehoe flows of Wood 

Valley (p2f7, FID 289; p2f9, FID 288). Age, 2,072±37 radiocarbon yr B.P. FID 295

a3a2, p3a2 Eastern Ka‘ōiki Pali flow—Aphanitic ‘a‘ā and minor pāhoehoe found on Keauhou Ranch in 

Kilauea Crater quadrangle. Rock is distinctive in that the groundmass is well crystallized and 

feldspathic, full of plagioclase microlites. Age, 2,265±49 radiocarbon yr B.P. FID 889

a3i3 Nīnole flow—Massive ‘a‘ā flow at south edge of Pahala quadrangle. Flow forms the northeast edge 

of Punalu‘u Beach. An aphyric ‘a‘ā has 0–1% each of olivine and plagioclase phenocrysts. The 

groundmass is dense, finely crystalline, and feldspathic. Flow has little to no ash cover. Age, 

2,365±30 radiocarbon yr B.P. FID 637

p3e4, m3e4, Cow Pasture picrite flow—Pāhoehoe, mostly in north-central Kipuka Pakekake, outliers in 

northern Wood Valley quadrangle. Flow has a weathered red-orange rind. Rock contains 

15–20% olivine phenocrysts, microphenocrysts. The groundmass is mildly feldspathic. Ash as 

thick as 0.5 m overlies this unit. Age, 2,826±32 radiocarbon yr B.P. FID 345
11

m3i8

a3l5, p3l5 Flow 891—‘A‘ā found just southwest of the A.D. 1880 flow. A very distinctive rock that has 

glomerocrysts of plagioclase and olivine. Contains 9% plagioclase and 6% olivine phenocrysts. 

All these minerals are contrasted against a dark-gray groundmass. Surface color of this flow is 

tan gray. FID 891

a3a6 Flow 357—Tiny, composed (~1 acre) of a 5-m-high ‘a‘ā. Rock is dense, and the surface lichen 

covered. Flow is aphyric with sparse angular vesicles. Unit is found in contact with A.D. 1880 

flow on the southwest side in central Kipuka Pakekake quadrangle. FID 357

m3a7 ‘Alili flow—Mixed ‘a‘ā and pāhoehoe along the west boundary of Pahala quadrangle. Contains 

0–1% olivine and 0–1% plagioclase phenocrysts in a light-gray, diktytaxitic groundmass. Flow 

is blanketed by 0.3–1 m of ash. FID 554

a3i8, p3i8, Flow 884—Dense, weathered ‘a‘ā and tube-fed pāhoehoe, near the west margin of Kilauea Crater 

quadrangle. Contains dark-gray groundmass, 2–5% olivine phenocrysts, and 1–2% plagioclase 

as microphenocrysts and rare phenocrysts. Vesicles are subangular to subrounded and may be 

magnesioferrite lined. Surface is broken and weathered red. FID 884

p3a9 Ka‘ala‘ala flow—Pāhoehoe contains 0–1% olivine in a well-crystallized feldspathic to diktytaxitic 

groundmass. Found in southwestern Wood Valley quadrangle. Flow is very similar in 

mineralogy to those surrounding it. The difference being that this unit is buried by 1–3 m of ash 

and (or) colluvium. FID 291

p3b10 Flow 296—Tube-fed pāhoehoe of lower Keaīwa Gulch (northern Pahala quadrangle). Contains 

0–3% olivine phenocrysts. The olivines are light green and sugary in appearance and are small 

and inconspicuous. The groundmass is well crystallized, feldspathic to diktytaxitic in texture. 

Flow is mantled by ash. FID 296

Age Group 4 (3,000–4,000 yr B.P.; Holocene)

p4a1 ‘Ōhaikea flow—Pāhoehoe of ‘Ōhaikea (in southwest corner of Kilauea Crater quadrangle). 

Contains 2–3% plagioclase microphenocrysts. The plagioclases are fine grained, 

usually <0.5 mm. Rare olivine occasionally found. Unit is covered by 10–50 cm of ash. Age, 

3,630±80 radiocarbon yr B.P. FID 892

p4g2, a4g2 Flow 899—Kīpuka in the northeast quadrant of Kipuka Pakekake quadrangle in contact with A.D. 

1880 flow. Pāhoehoe contains 3–5% plagioclase phenocrysts in a well-crystallized light-gray 

groundmass. Unit is covered with 0.2–0.5 m of ash. FID 899

p4a3, a4a3 Flow 401—Small kīpukas in southwest corner of Kipuka Pakekake quadrangle. Flow is orangeweathered aphanitic pāhoehoe. Contains 0–1% olivine phenocrysts in well-crystallized lightgray groundmass. Unit here is covered with 0–0.5 m of ash in low-lying areas. FID 401

p4k4 Flow 339—Distinctive plagioclase pāhoehoe, in central Wood Valley quadrangle. Contains 5–8% 

plagioclase as anhedral snowflake clusters. In addition, unit contains 3–5% olivine phenocrysts 

in light-gray, well-crystallized groundmass. FID 339

p4l5 Wai‘akaloa Gulch flow—Distinctive plagioclase-bearing pāhoehoe flow containing 7–10% olivine 

as phenocrysts and microphenocrysts and 7–10% plagioclase as glomeroclasts in a diktytaxitic 

groundmass. Flow is overlain by ash as thick as 0.3 m. Unit is found in south-central Wood 

Valley quadrangle. FID 342

p4c6 Flow 352—Tan-orange-weathered pāhoehoe in west-central Kipuka Pakekake quadrangle, found as 

kīpuka in flow p2e8 (FID 346). Flow contains 8% olivine as very fine laths and phenocrysts 

in a gray groundmass. In contrast to knobby surface of p2e8 (FID 346), this unit has a smooth 

surface. Flow mantled by ash. FID 352

a4l7 Flow 882—‘A‘ā along west boundary of Kilauea Crater quadrangle. Contains 8–12% olivine 

phenocrysts, 8–15% plagioclase phenocrysts, and 5–6% olivine-plagioclase intergrowths. 

Plagioclase is more conspicuous than olivine. Unit covered by layers of yellow ash, probably 

from Kīlauea Volcano, in low-lying areas. FID 882

a4j8 Flow 890—Thick ‘a‘ā west of Ke‘āmuku Kīpukakēkake flow in central Kilauea Crater quadrangle. 

Rock is characterized by 6% olivine and 1–3% plagioclase phenocrysts. Groundmass is well 

crystallized and full of plagioclase microlites. FID 890

a4a9, p4a9 Flow 351—‘A‘ā with minor pāhoehoe in northwest corner of Kipuka Pakekake quadrangle. Unit 

nearly aphanitic yet contains 0.5% olivine-plagioclase glomeroclasts. Groundmass is medium 

dark gray. Upper surfaces are orange tan. FID 351

a4a10 Flow 348—Aphanitic ‘a‘ā, east of Napu‘ukūlua Lava Flow, in the northwest corner of Kipuka 

Pakekake quadrangle. Unit is a kīpuka in the younger p3e4 (FID 345). Surface color is 
12

m5b7

chocolate gray brown. Abundant ash fills all interstices between (mostly round) clinkers. 

Contains 0.5% plagioclase phenocrysts in a medium-light-gray groundmass. Olivine rare, 

usually intergrown with plagioclase. FID 348

p4a11, m4a11 Flow 844—Small pāhoehoe and mixed ‘a‘ā and pāhoehoe kīpuka in the north-central portion of 

Kipuka Pakekake quadrangle. Units are aphanitic. Pāhoehoe contains 0–1% olivine phenocrysts 

in a well-crystallized light-gray groundmass. FID 844

p4a12 Flow 895—Pāhoehoe originates from spatter ramparts uprift of Pu‘u‘ula‘ula cone in Kokoolau 

quadrangle (west of map area). Represents only flows found in Kipuka Pakekake quadrangle. 

Nearly aphyric, with rare phenocrysts of olivine and plagioclase. Groundmass is medium gray, 

microcrystalline, and mildly feldspathic with abundant plagioclase microlites. A very large tube 

system lies within the pāhoehoe. Surface is tan. FID 895

Age Group 5 (4,000–5,000 yr B.P.; Holocene)

m5a1 Halfway House flow—Small kīpuka in southeastern Kipuka Pakekake and northeastern Wood 

Valley quadrangles. Unit under 1 m of ash is a dense aphanitic ‘a‘ā and pāhoehoe. Groundmass 

is feldspathic, full of plagioclase microlites. Age, 4,378±42 radiocarbon yr B.P. FID 399

p5a2, m5a2 Flow 880—Aphanitic pāhoehoe and dense, fluid, ‘a‘ā in contact with A.D. 1984 along north 

boundary of Kipuka Pakekake quadrangle. Flow is characterized by its well-crystallized, 

medium-gray, feldspathic groundmass. FID 880

a5b3 ‘Ahulili flow—Kīpuka in southwest quadrant of Wood Valley quadrangle. ‘A‘ā contains 5% olivine 

phenocrysts in microcrystalline, steely gray groundmass. Unit is blanketed by 2–3 m of ash. 

FID 379

p5h4, a5h4 Flow 392—Kīpuka in north-central Wood Valley and southwestern Kipuka Pakekake quadrangles. 

A distinctive coarse plagioclase-rich, tube-fed pāhoehoe. Contains variable plagioclase 

phenocrysts at 10–20%. Plagioclase comprises aggregates of euhedral plagioclase laths 

(to 3 mm) as glomerocrysts, all in a dark-gray glassy groundmass. Upper surface is orange 

stained, weathered, glass speckled by coarse plagioclase. Unit is covered by 0–30 cm of ash. 

FID 392

p5a5 Ka‘ili‘ula flow—Large ash-covered kīpuka upslope of Kapāpala Ranch headquarters in Wood Valley 

quadrangle. Flow is sparsely olivine-phyric tube-fed pāhoehoe. Contains 0–1% olivine phenocrysts 

in light-gray, feldspathic to diktytaxitic groundmass. Unit overlain by 0.5–2 m of ash. FID 397

p5f6 Uēwale Gulch flow—Kīpuka in center of Wood Valley quadrangle. Pāhoehoe contains 

variable amounts of olivine at 5–15% phenocrysts. Groundmass is a bluish-gray color and 

cryptocrystalline. Flow differs from other nearby younger regional olivine pāhoehoe by the 

amount of ash cover, 1–4 m, and its more weathered, eroded upper surface. FID 378

a5b7, p5b7, Kīpukakēkake flow—‘A‘ā and slabby, tube-fed pāhoehoe in north-central Kilauea Crater 

quadrangle. In contact with and isolated by Ke‘āmuku Kīpukakēkake flow (a1g1, FID 800). 

Rare toothpaste and ‘a‘ā phases exist in southernmost reach of the flow. Contains 0–2% widely 

scattered olivine phenocrysts in a gray feldspathic groundmass. Ash cover is nearly continuous. 

Abundant charcoal samples found where overlain by toes of Ke‘āmuku Kīpukakulalio east flow 

(p1k5, FID 799). FID 870

s5a8 Pu‘ukīpū cone—Poorly exposed spatter cone at 4,274-ft elev in northeastern part of Kilauea Crater 

quadrangle. Spatter is fine grained and aphanitic. FID 871

Age Group 6 (5,000–6,000 yr B.P.; Holocene)

a6d1 Flow 988—‘A‘ā found at distal end and northeast of A.D. 1880 flow. Contains 8–12% olivine 

phenocrysts in a medium-gray groundmass. Unit is covered by 0.25 m of ash. FID 988

a6k2 Kīpukapakēkakē flow—Distinctive plagioclase-bearing ‘a‘ā contains 5–7% plagioclase 

glomerocrysts (”snowflakes”) and 3–4% inconspicuous olivine phenocrysts. Olivine commonly 

associated with plagioclase. Groundmass medium to dark gray and feldspathic; vesicles are 

small and well sorted. Unit found in northwestern Kipuka Pakekake quadrangle and southwest 

of the distal end of A.D. 1880 flow, along the boundary between the Kilauea and Kipuka 

Pakekake quadrangles. FID 398

a6c3 Flow 990—Olivine-bearing ‘a‘ā in northwest quadrant of Kilauea Crater quadrangle along Strip Road. 

Flow contains 8–10% sugary anhedral olivine phenocrysts and microphenocrysts. Groundmass is 

well crystallized and full of plagioclase microlites. Flow is mantled by ash. FID 990

a6a4 Pu‘u 4274 flow—‘A‘ā in northwest corner of Kilauea Crater quadrangle. This unit is aphanitic. 

Flow is covered by 1–2 m ash. FID 986
13

a10b1

Age Group 7 (6,000–7,000 yr B.P.; Holocene)

[No units of this age group are found at the surface in the map area]

Age Group 8 (7,000–8,000 yr B.P.; Holocene)

p8e1 Palakea Flat flow—Picritic pāhoehoe comprises all of the Mauna Loa flows in Volcano 

quadrangle and northeastern-most Kilauea Crater quadrangle. Characterized by 25–30% clear, 

large, subhedral to anhedral olivine and 0–2% plagioclase phenocrysts, mostly intergrown 

with olivine. Vesicles are highly irregular in distribution, subrounded, and commonly 

magnesioferrite lined. Flow is commonly covered with as much as 2 m of tan ash; outcrops 

are fairly common. Dzurisin and others (1995) map distal extent of Uwēkahuna Ash member 

of Puna Basalt to this unit, a distance of approximately 6 km from Kīlauea Volcano summit. 

Age, 7,960±110 radiocarbon yr B.P. FID 962

p8b2, a8b2 Flow 400—Spongy tube-fed pāhoehoe contains 2–5% inconspicuous olivine phenocrysts in a 

well-crystallized groundmass. Upper surfaces are deeply weathered and orange stained. Flow is 

found in extreme southwest corner of Kipuka Pakekake quadrangle and is covered by 0.2–1 m 

of ash. FID 400

m8k3, p8k3 Flow 983—‘A‘ā along boundary dividing Kipuka Pakekake and Kilauea Crater quadrangles. 

Flow surface severely broken and weathered, retaining very little surface glass and stained 

red orange. Minor olivine phenocrysts form 1–2% of rock and are mostly intergrown with 

plagioclase. Abundant, large plagioclase makes up 6–10% of rock. Rich soil/ash horizons 

support ‘ōhi‘a trees as tall as 4 m. FID 983

a8i4, p8i4 Flow 979—‘A‘ā and pāhoehoe in extreme northwest corner of Kilauea Crater quadrangle. Flow 

contains 1–2% of clear, inconspicuous olivine and 0–2% very fine plagioclase phenocrysts. 

Flow has no original surface glass, and deep orange rind is common. Overlain by pockets of 

yellow-brown ash as thick as 0.5 m. FID 979

p8e5 ‘Ua‘u flow—Flow in northwestern and east-central Kipuka Pakekake quadrangle. Pāhoehoe 

containing 15–25% olivine phenocrysts. Groundmass is light gray and diktytaxitic. Surface is 

broken up and deep red. Unit represents some of the oldest rocks on this portion of the volcano. 

This unit harbors pockets of ash, as thick as 40 cm, in low-lying regions. FID 385

Age Group 9 (8,000–9,000 yr B.P.; Holocene)

p9h1 Halfway House Kīpuka flow—Pāhoehoe located in southeast corner of Kipuka Pakekake and northeastern Wood Valley quadrangles, with distinctive snowflakes or rosettes of plagioclase. Contains 

18–20% euhedral blades intergrown to form glomeroclasts of plagioclase. Unit also contains minor 

olivine. Flow is covered by 0.5 to 1.5 m of ash. Age, 8,520±82 radiocarbon yr B.P. FID 395

p9g2, a9g2 Pu‘u‘ula‘ula flow—Pāhoehoe, and minor ‘a‘ā, from Pu‘u‘ula‘ula, one of largest cones on NERZ. 

Located in central part of Kilauea Crater quadrangle. Distinct unit, containing 3–4% fine plagioclase phenocrysts. Flow groundmass is light gray and orange stained, with many inconspicuous 

needles of plagioclase. Flow is commonly covered with as much as 1 m of tan ash, especially at 

lower elevations; outcrops are fairly common. Age, 8,645±71 radiocarbon yr B.P. FID 978

a9k3 Flow 402—‘A‘ā in northwest corner of Wood Valley quadrangle. Contains 8–10% anhedral 

plagioclase glomeroclasts and laths in a well-crystallized groundmass. Flow has 1% olivine 

phenocrysts. Upper surfaces are orange stained. Unit is covered by 0.5 m of ash. FID 402

p9b4 Flow 393—Tube-fed pāhoehoe found in northwest quadrant of Wood Valley and southeast 

corner of Kipuka Pakekake quadrangles. Unit has orange, weathered, glassy rind top and 

is characteristically overlain by 1 m of ash. Contains 5% olivine as inconspicuous anhedral 

phenocrysts and rare laths. FID 393

a9b5, p9b5 Flow 944—Old ‘a‘ā and tube-fed pāhoehoe, yellow stained and exposed only in gullies. Contains 

1–2% anhedral olivine phenocrysts in a well-crystallized groundmass. Upper surfaces are 

orange stained. Flow is covered by 0.2–1 m of ash. Unit forms small kīpuka within largest 

p9g2 (FID 978) unit near Kīlauea Volcano contact in central Kilauea Crater quadrangle. 

FID 944

Age Group 10 (9,000–10,000 yr B.P.; Holocene)

m10b1, p10b1, Ka‘ū High School flow—Tube-fed pāhoehoe that underlies the town of Pāhala. Contains 0–5% 

olivine phenocrysts in a well-crystallized groundmass. Flow tops are stained orange red. Flow 

is buried by 1.5–2 m of ash. Age, 9,121±46 radiocarbon yr B.P. FID 383
14

a10k4

p10c2 Lae‘opuhili flow—Large regional pāhoehoe in Pahala quadrangle. Pāhoehoe contains 7–10% 

olivine phenocrysts in light-gray diktytaxitic groundmass. Unit is covered by 0.3 to 1 m of ash. 

Age, 9,218±79 radiocarbon yr B.P. FID 742

p10a3 Flow 338—Abandoned cane fields, ash covered, below Kapāpala Ranch Headquarters in 

southern Wood Valley quadrangle. Flow buried by 0.5–1.2 m of ash. Pāhoehoe has 0–1% 

olivine phenocrysts and microphenocrysts in a dull light-gray microcrystalline groundmass. 

Age, 9,680±70 radiocarbon yr B.P. FID 338

m10k4, p10k4, ʻIliokōloa flow—Flow in Pahala quadrangle. Unit has both ‘a‘ā and pāhoehoe phases, informally 

known as the “plagioclase-rich flow” of Pahala quadrangle. Plagioclase ranges from 

3–8% as anhedral clots and laths. Also contains 1–8% olivine as green phenocrysts and 

microphenocrysts. Unit is overlain by 0.5 to 5 m of ash. FID 382

a10i5 Flow 943—Small ash-covered ‘a‘ā kīpuka in southwestern part of Kilauea Crater quadrangle; 

surrounded by ash (ts) unit. Contains 5% plagioclase and 3% sugary olivine phenocrysts in a 

dense microcrystalline groundmass. Unit is covered by 2.5 m of ash. FID 943

p10g6 Flow 942—Small ash-covered pāhoehoe kīpuka in southwestern part of Kilauea Crater quadrangle, 

surrounded by ash (ts) unit. Contains 4–5% plagioclase in a dense microcrystalline 

groundmass. Unit is covered by 1.0–2.5 m of ash. FID 942

Age Group 11 (10,000–15,000 yr B.P.; Holocene and Pleistocene)

p11a1 Kauhuhu‘ula flow—Aphyric pāhoehoe of Kauhuhu‘ula Gulch, Pahala quadrangle. Contains rare olivine 

phenocrysts. The groundmass is full of plagioclase microlites. Surface color of flow is yellow orange. 

Unit is buried by 1.5 m of ash. Ka‘ū High School flow (m10b1, FID 383) overlies this unit. FID 390

a11a2, p11a2 Pā‘au‘au flow—Mixed ‘a‘ā and pāhoehoe of Pā‘au‘au Gulch in central Pahala quadrangle. Contains 

0–1% olivine phenocrysts and microphenocrysts. Groundmass is dense and microcrystalline. 

Unit is buried by 1.0 m of ash. Age, 10,030±85 radiocarbon yr B.P. FID 388

p11b3 Meyer Camp flow—Very vesicular pāhoehoe with near-vent-type vesicularity in central Pahala 

quadrangle. Outcrop appears to be large tube system and (or) channel overbank deposit. 

Contains 2–3% olivine phenocrysts in microcrystalline gray groundmass. Unit is buried by 

1–2 m of ash. Age, 10,600±150 radiocarbon yr B.P. FID 386

a11a4 Wailoa flow—Aphyric ‘a‘ā northeast of Pāhala town. Unit contains rare olivine phenocrysts. 

Groundmass is full of plagioclase microlites. Surface color of flow is yellow orange. Flow is 

buried by 1.5 m of ash. Ka‘ū High School flow (m10b1, FID 383) overlies this unit. FID 391

Age Group 12 (15,000–20,000 yr B.P.; Pleistocene)

[No units of this age group are found at the surface in the map area]

Age Group 13 (20,000–30,000 yr B.P.; Pleistocene)

m13b1 Flow 387—Mixed ‘a‘ā and pāhoehoe above town of Pāhala occurs as two kīpuka within Ka‘ū High 

School flow (m10b1, FID 383). Unit contains 0–3% olivine phenocrysts in a well-crystallized 

groundmass. Flow tops are stained orange red. Unit is buried by 1.5–2 m of ash. FID 387

a13b2 Flow 384—Lava flow in section at Hi‘onamoa Gulch. ‘A‘ā contains variable amounts of olivine 

phenocrysts from 1–7% in a microcrystalline bluish-gray groundmass. Flow is under Ka‘ū 

High School flow (m10b1, FID 383). Unit is covered by 0.5–1.0 m of ash. Age, 25,768±188 

radiocarbon yr B.P. FID 384

a13f3, p13f3 Lava flow of Hi‘onamoa Gulch—‘A‘ā and pāhoehoe lining the floor of Hi‘onamoa and Moa‘ula 

Gulches near Highway 11 in Pahala quadrangle. Contains variable amounts of olivine, ranging 

from 0–8% as phenocrysts in a microcrystalline bluish-gray groundmass. Flow is overlain by 

the Ka‘ū High School flow (m10b1, FID 383). Unit is covered by 0.5–1.0 m of ash. Age, 

28,140±590 radiocarbon yr B.P. FID 735

Kahuku Basalt

The Kahuku Basalt consists of units with an age range of 30,000 to 100,000 yr. The Kahuku Basalt is 

composed of tholeiitic basalt, tuffs, vent deposits, and lava flows that rest unconformably on the Nīnole Basalt. The 

flows are mostly aphyric and some have variable amounts of olivine and plagioclase phenocrysts. The Kahuku Basalt 

type locality is the Kahuku Pali or Kahuku Fault near Kalae (South Point).
15

Age Group 14 (30,000–100,000 yr B.P.; Pleistocene)

[No units of this age group are found at the surface in the map area]

Nīnole Basalt

The Nīnole Basalt, the oldest exposed rocks on Mauna Loa, is >100,000 yr B.P. These rocks are exposed 

in the Ka‘ū District. The Nīnole Basalt consists of tholeiitic basalt, tuffs, vent deposits, and lava flows. The flows are 

mostly aphyric and some have variable amounts of olivine and plagioclase phenocrysts. 

Age Group 15 (>100,000 yr B.P.; Pleistocene)

n Nīnole Basalt—Undivided units found in valley wall of Wood Valley. Flows are mostly aphyric and 

deeply weathered and have variable amounts of olivine and plagioclase phenocrysts. Lipman 

and others (1990) report a weighted mean age of 0.120±0.056 Ma for Nīnole Basalt. Whereas, 

Jicha and others (2012) constrain the Nīnole Basalts to have erupted from 0.227 to 0.108 Ma. 

FID 744

DISTAL TEPHRA DEPOSITS

Tephra (Holocene and Pleistocene)

ts Southern tephra—Beds of ashfall deposits in map area are chiefly from Kīlauea Volcano and 

likely include contributions from Mauna Loa (Easton, 1987). All ash deposits ≤10,000 yr 

B.P. are included in this category. Kīlauea deposits include 14C ages of 2,110±120 yr B.P., 

2,265±50 yr B.P., and 2,770±70 yr B.P., all dating Uwēkahuna Ash Member of Puna Basalt 

(Dzurisin and others, 1995). Other ages of 4,135±49 and 9,500±140 yr B.P. were obtained 

from ash layers on the east flank of the volcano. Distributions of ash near Kīlauea seem to 

be influenced by the inversion layer on the windward coast of the Island of Hawai‘i. This 

meteoric phenomenon appears to limit distribution of ash to lower elevations; therefore, 

overlay patterns for ash deposits may vary with elevation within flows or on flows of similar 

age. Possibly, ash deposited at higher elevations (alpine and above) lack vegetative cover 

that preserves it, allowing combined wind and rainfall to strip ash deposits from higher 

elevations. FID 959

pa Pāhala Ash—Deep Pāhala Ash 5–8 m thick exposed at the surface. Unit comprises several 

kīpukas in northwest-central Pahala quadrangle. Unit is older than surficial ash deposits 

(ts; FID 959). Unit comprises multiply bedded airfall deposits whose origin is unknown. 

Most likely, Pāhala Ash has Kīlauea Volcano origin, although Mauna Loa cannot be 

excluded as a source. Unit is overlain by flows p11a1 (FID 390) and p11a2 (FID 388), 

dated at 12,500 and 10,030 radiocarbon yr B.P., respectively. Age, 31,020±310 radiocarbon 

yr B.P. FID 389
16

Selected References

Buchanan-Banks, J.M., 1993, Geologic map of Hilo 7 1/2' 

quadrangle, Island of Hawaii: U.S. Geological Survey 

Miscellaneous Investigations Series Map I–2274, scale 

1:24,000, 17 p.

Buchanan-Banks, J.M., Lockwood, J.P., and Rubin, Meyer, 

1989, Radiocarbon dates for lava flows from Northeast Rift 

Zone of Mauna Loa volcano, Hilo 7 1/2' quadrangle, Island 

of Hawaii: Radiocarbon, v. 31, no. 2, p. 179–186.

Dzurisin, D., Lockwood, J.P., Casadevall, T.J., and Rubin, 

Meyer, 1995, The Uwekahuna Ash Member of the Puna 

Basalt—Product of violent phreatomagmatic eruptions 

at Kīlauea Volcano, Hawai‘i, between 2,800 and 2,100 

14C years ago: Journal of Volcanology and Geothermal 

Research, v. 66, no. 1–4, p. 163–184.

Easton, M., 1987, Stratigraphy of Kilauea Volcano, in Decker, 

R.W., Wright, T.L., and Stauffer, P.H., eds., Volcanism in

Hawaii: U.S. Geological Survey Professional Paper 1350,

v. 1, chap. 11, p. 243–260.

Finch, R.H., and Macdonald, G.A., 1953, Hawaiian volcanoes 

during 1950: U.S. Geological Survey Bulletin 996–B, 

p. 27–89.

Fraser, G.D., 1960, Pahala ash—An unusual deposit from 

Kilauea Volcano, Hawaii: U.S. Geological Survey Professional Paper 400–B, p. 354–355.

Jackson, M.D., Endo, E.T., Delaney, P.T., Arnadottir, T., and 

Rubin. A.M., 1992, Ground ruptures of the 1974 and 

Kaoiki earthquakes, Mauna Loa, Hawaii: Journal of Geophysical Research, v. 97, no. B6, p. 8775–8796.

Jicha, B.R., Rhodes, J.M., Singer, B.S., and Garcia, M.O., 

2012, 40Ar/ 39Ar geochronology of submarine Mauna Loa 

volcano, Hawaii: Journal of Geophysical Research B, Solid 

Earth, v. 117, no. 9, 10.1029/2012JB009373, B09204.

Kelley, M.L., 1979, Radiocarbon dates from the Hawaiian 

Islands—A compilation: U.S. Geological Survey OpenFile Report 79–1700, 37 p.

Kelley, M.L., Spiker, E.C., Lipman, P.W., Lockwood, J.P., 

Holcomb, R.T., and Rubin, Meyer, 1979, U.S. Geological 

Survey, Reston, Virginia, Radiocarbon Dates XV—Mauna 

Loa and Kilauea volcanoes, Hawaii: Radiocarbon, v. 21, 

no. 2, p. 306–320.

Lipman, P.W., 1980, Rates of volcanic activity along the southwest rift zone of Mauna Loa Volcano, Hawaii: Bulletin 

Volcanologique, v. 43, no. 4, p. 703–725.

Lipman, P.W., and Swenson, A., 1984, Generalized geologic 

map of the southwest rift zone of Mauna Loa volcano, 

Hawaii: U.S. Geological Survey Miscellaneous Investigations Series Map I–1323, scale 1:100,000.

Lipman, P.W., Rhodes, J.M., and Dalrymple, G.B., 1990, The 

Ninole Basalt—Implications for the structural evolution of 

Mauna Loa volcano, Hawaii: Bulletin of Volcanology, v. 

53, p. 1–19. 

Lockwood, J.P., 1995, Mauna Loa eruptive history—The 

preliminary radiocarbon record, in Rhodes, J.M., and 

Lockwood, J.P., eds., Mauna Loa revealed—Structure, 

composition, history, and hazards: American Geophysical 

Union Geophysical Monograph 92, p. 81–94.

Lockwood, J.P., Banks, N.G., English, T.T., Greenland, L.P., 

Jackson, D.B., Johnson, D.J., Koyanagi, R.Y., McGee, 

R.A., Okamura, A.T., and Rhodes, J.M., 1985, The 1984

eruption of Mauna Loa Volcano, Hawaii: Eos, Transactions, American Geophysical Union, v. 66, no. 16, p.

169–171.

Lockwood, J.P., and Lipman, P.W., 1980, Recovery of datable 

charcoal from beneath young lava flows—Lessons from 

Hawaii: Bulletin Volcanologique, v. 43, no. 3, p. 609–615.

Lockwood, J.P., and Lipman, P.W., 1987, Holocene eruptive 

history of Mauna Loa volcano, in Decker, R.W., Wright, 

T.L., and Stauffer, P.H., eds., Volcanism in Hawaii: U.S.

Geological Survey Professional Paper 1350, v. 1, chap. 18,

p. 509–536.

Rubin, Meyer, Gargulinski, L.K., and McGeehin, J.P., 1987, 

Hawaiian radiocarbon dates, in Decker, R.W., Wright, T.L., 

and Stauffer, P.H., eds., 1987, Volcanism in Hawaii: U.S. 

Geological Survey Professional Paper 1350, v. 1, chap. 10, 

p. 213–242.

Stearns, H.T., and Clark, W.O., 1930, Geology and water 

resources of the Kau District, Hawaii: U.S. Geological 

Survey Water-Supply Paper 616, 194 p.

Stearns, H.T., and Macdonald, G.A., 1946, Geology and 

ground-water resources of the island of Hawaii: Hawaii 

(Territory) Division of Hydrography Bulletin 9, scale 

1:125,000, 363 p.

Stone, J.B., 1926, The products and structure of Kilauea: Bernice P. Bishop Museum, Bulletin 33, 59 p., includes plates.

Stuiver, Minze, Reimer, P.J., Bard, Edouard, Beck, J.W., 

Burr, G.S., Hughen, K.A., Kramer, Bernd, McCormac, 

Gerry, van der Plicht, Johannes, and Spurk, Marco, 1998, 

INTCAL98 radiocarbon age calibration, 24,000–0 cal BP: 

Radiocarbon, v. 40, no. 3, p. 1041–1083.

Stuiver, M., Reimer, P.J., and Reimer, R.W. 2005, CALIB 

Radiocarbon Calibration: Marine Reservoir Correction 

Database (program and documentation), v. 6.0, http://

calib.org/calib/.

Taylor, J.R., 1982, An introduction to error analysis: Mill 

Valley, Calif., University Science Books, 270 p.

Trusdell, F.A., 1995, Lava flow hazards and risk assessment on 

Mauna Loa Volcano, Hawaii, in Rhodes, J.M., and Lockwood, J.P., eds., Mauna Loa revealed—Structure, composition, history, and hazards: American Geophysical Union, 

Monograph 92, p. 327–336.

Walker, G.W., 1969, Geologic map of the Kau Desert quadrangle, Hawaii: U.S. Geological Survey Geologic Quadrangle 

Map GQ–827.

Wentworth, C.K., 1938, Ash formation of the Island of Hawaii: 

Honolulu, Hawaiian Volcano Observatory of Hawaii
17

FID1 Field No. Lab No. Quadrangle name

(1:24,000)

Age2

(yr B.P.)

S.D.2

(yr) Data source3

289 9P74C W5325 Pahala 1,370 200 1

289 L-01-501c WW3711 Wood Valley 1,560 35 1

289 L-90-81 W6456 Wood Valley 1,820 80 1

289 L-91-143 W6460 Keaiwa Reservoir 1,850 80 1

289 L-91-191 W6462 Wood Valley 1,920 80 1

344 L-81-67 W5083 Mauna Loa 1,030 60 1

799 L-77-42A W3879 Kilauea Crater 830 60 1

799 KUc-130 W4870 Kulani 1,100 70 2

801 77L-09 W3836 Kilauea Crater 2,830 60 2

801 L-80-126 W4801 Kilauea Crater 730 70 2

838 L-78-1 W4049 Kipuka Pakekake 420 70 2

838 PUd-135 W4571 Puu Ulaula 440 70 2

892 77L-08 W3855 Kilauea Crater 4,210 200 1

1Unique three-digit flow identification number (FID) assigned to each mapped flow unit is necessary to utilize associated database 

(https://doi.org/10.3133/sim2932B).

2Each age was calibrated to calendar years using CALIB 6.0 Radiocarbon Calibration Program (Stuiver and others, 2005); calibrated ages are 

for two standard deviations (S.D.). Samples were processed at U.S. Geological Survey, 14C Laboratory, Reston, Va.

3

Sources: 1, this study; 2, Kelley and others (1979).

Appendix

This appendix contains radiocarbon ages that were rejected and not used in the study of the central-southeast flank of Mauna 

Loa volcano, Island of Hawai‘i, Hawaii. Reasons for being rejected include age too old or too young, age not consistent with 

stratigraphy, and sample contaminated.

National Park and Hawaiian Volcano Research Association, 3rd special report, 183 p.

Wolfe, E.W., and Morris, Jean, 1996a, Geologic Map of the 

Island of Hawaii: U.S. Geological Survey Miscellaneous 

Investigations Series Map I–2524–A, scale 1:100,000, 

18 p.

Wolfe, E.W., and Morris, Jean, 1996b, Sample data for the geologic map of the Island of Hawaii: U.S. Geological Survey 

Miscellaneous Investigations Series Map I–2524–B, scale 

1:100,000, 51 p.

Hawaiian Language References

Pukui, M.K., Elbert, S.H., and Mookini, E.T., 1974, Place names 

of Hawaii: Honolulu, University of Hawaii Press, 289 p.

United States Board on Geographic Names, 2018, Geographic 

names database: U.S. Geological Survey, https://geonames.

usgs.gov/.

University of Hawaii Geography Department, 1974, Atlas of 

Hawaii: Honolulu, University of Hawaii Press, 250 p.
18

Unit label1 FID2 Age1

group

Unit name Field No. Lab No.3 Quadrangle name 

(1:24,000)

a1g1 800 1 Ke‘āmuku Kīpukakēkake flow 77L-24A W3871 Kilauea Crater

a1g1 800 1 Ke‘āmuku Kīpukakēkake flow L-78-26 W4360 Kilauea Crater

a1g1 800 1 Ke‘āmuku Kīpukakēkake flow 77L-24B W4919 Kilauea Crater

p1k2 801 1 Kīpukamauna‘iu flow 77L-06 W3843 Kilauea Crater

p1k2 801 1 Kīpukamauna‘iu flow 77L-29 W4006 Kilauea Crater

p1k2 801 1 Kīpukamauna‘iu flow L-78-14 W4183 Kipuka Pakekake

p1k2 801 1 Kīpukamauna‘iu flow L-82-01 W5106 Kilauea Crater

p1k2 801 1 Kīpukamauna‘iu flow F01-37-01c WW3541 Kilauea Crater

p1a3 274 1 Ke A Po‘omoku Flow L-80-100 W4790 Kipuka Pakekake

p1a3 274 1 Ke A Po‘omoku Flow L-80-165 W4805 Kilauea Crater

p1a3 274 1 Ke A Po‘omoku Flow L-87-07 W6001 Kipuka Pakekake

p1g4 802 1 Ke‘āmuku Kīpukakulalio flow L-78-0410 W4118 Puu Ulaula

p1g4 802 1 Ke‘āmuku Kīpukakulalio flow L-78-04R10 W4916 Puu Ulaula

a1k5 799 1 Ke‘āmuku Kīpukakulalio east flow L-77-42B W3880 Kilauea Crater

a1k5 799 1 Ke‘āmuku Kīpukakulalio east flow MP-78-07 W4367 Kilauea Crater

a1k5 799 1 Ke‘āmuku Kīpukakulalio east flow L-80-24 W4845 Kilauea Crater

p1l6 833 1 Keauhou Ranch flow L-78-27 W4345 Kilauea Crater

a1b7 840 1 Flow northeast of 1880 lobe L-80-90 W4863 Kipuka Pakekake

p1e8 837 1 Pu‘uwahi picrite flow L-77-45 W4047 Kipuka Pakekake

p1e8 837 1 Pu‘uwahi picrite flow L-77-45R SUERC-5409 Kipuka Pakekake

p2b2 293 2 West Wood Valley flow 9WV2C W4430 Wood Valley

p2b2 293 2 West Wood Valley flow MJ-87-C5 W6037 Pahala

p2i3 298 2 Pahuamimi flow L-93-119 USGS3466 Kipuka Pakekake

p2i3 298 2 Pahuamimi flow KP-01 W3000 Wood Valley

p2i3 298 2 Pahuamimi flow MJ-87-C2 W6014 Kipuka Pakekake

p2a4 297 2 Keakapulu Flat flow MJ-87-C3 W6012 Wood Valley

p2a4 297 2 Keakapulu Flat flow L-92-159 USGS3461 Wood Valley

p2i5 344 2 Kapāpala flow MJ-87-C4 W5982 Wood Valley

p2i5 344 2 Kapāpala flow L-92-181 WW323 Wood Valley

p2i5 344 2 Kapāpala flow L-92-212 USGS3462 Kipuka Pakekake

p2c6 301 2 Kilohana flow L-91-58810 WW319 Keaiwa Reservoir

p2c6 301 2 Kilohana flow L-92-654 USGS3474 Wood Valley

p2c6 301 2 Kilohana flow MJ-87-C1 W5679 Wood Valley

p2f7 289 2 Waimuku flow L-84-06c W5461 Wood Valley

p2f7 289 2 Waimuku flow 77L-63 W4359 Pahala

p2f7 289 2 Waimuku flow L-01-501c WW3711 Wood Valley

p2f7 289 2 Waimuku flow 77L-17A W3857 Pahala

p2f7 289 2 Waimuku flow 77L-17B W3858 Pahala

p2e8 346 2 Pu‘u‘ele‘ele flow L-92-129 WW846 Wood Valley

p2e8 346 2 Pu‘u‘ele‘ele flow L-93-242 WW852 Kipuka Pakekake

p2f9 288 2 Ka‘ala‘ala Gulch flow L-92-2014 SUERC10374 Pahala

p2f9 288 2 Ka‘ala‘ala Gulch flow L-92-507D SUERC10382 Pahala

p2b10 290 2 Kapāpala Ranch flow L-91-60210 USGS3468 Keaiwa Reservoir

p2b10 290 2 Kapāpala Ranch flow L-99-553 WW2626 Wood Valley

Table 2. Radiocarbon ages of samples from the central-southeast flank of Mauna Loa volcano, Island of Hawai‘i, Hawaii.

[All ages are reported in radiocarbon years before present (yr B.P., before the calendar year datum of A.D. 1950). Materials dated include charcoal, roots, twigs, vegetative litter, or 

unaltered wood (rarely). See figure 1 for quadrangle locations]
19

Latitude4

(degree)

Longitude4

(degree)

 Elev

(ft)

Age5

(yr B.P.)

S.D.5

(yr)

Weighted average6

(yr B.P.) 

S.D.6

(yr) Quality7 Age range8

 

(calendar years) Source9

19.44321 -155.31630 4,200 230 60 288 36 + 1491 to 1953 1, 2

19.49084 -155.34227 5,500 300 60 288 36 + 1448 to 1951 2

19.44324 -155.31627 4,203 350 70 288 36 0 1433 to 1790 2

19.40565 -155.34085 3,500 290 50 311 25 — 1460 to 1950 1,2

19.40897 -155.33940 3,590 290 70 311 25 0 1447 to 1951 1,2

19.49261 -155.44146 8,360 300 60 311 25 + 1448 to 1951 1, 2

19.41252 -155.34698 3,825 300 80 311 25 + 1437 to 1952 2

19.41124 -155.34172 3,570 340 40 311 25 — 1462 to 1642 3

19.43715 -155.39977 5,280 540 70 475 41 + 1285 to 1464 2

19.39405 -155.36860 3,790 340 60 475 41 0 1445 to 1653 2

19.40651 -155.38265 4,350 720 100 475 41 0 1048 to 1422 3

19.50088 -155.38320 6,815 580 80 569 53 + 1274 to 1449 1,2

19.50088 -155.38320 6,815 560 70 569 53 + 1287 to 1446 3

19.45195 -155.28359 4,100 530 60 575 38 + 1296 to 1453 1,2

19.44277 -155.27337 4,060 570 70 575 38 + 1286 to 1442 2

19.46805 -155.29302 4,425 640 70 575 38 0 1262 to 1424 2

19.48993 -155.34121 5,450 760 70 — — + 1050 to 1392 2

19.48373 -155.41635 7,395 780 70 — — + 1045 to 1387 2

19.48408 -155.38352 6,350 910 70 955 24 + 1016 to 1259 1, 2

19.48408 -155.38353 6,350 961 25 955 24 + 1020 to 1155 3

19.26468 -155.48276 2,260 1,270 70 1,281 66 + 645 to 940 2

19.22045 -155.46248 1,180 1,290 120 1,281 66 + 543 to 994 3

19.38563 -155.38252 3,720 1,285 30 1,293 27 + 662 to 777 3

19.37141 -155.37367 3,000 1,330 70 1,293 27 + 597 to 876 1

19.37390 -155.37478 3,380 1,310 120 1,293 27 + 467 to 992 3

19.37075 -155.39729 3,680 1,360 120 1,428 38 + 428 to 948 3

19.33970 -155.42802 3,190 1,435 40 1,428 38 + 556 to 660 3

19.35599 -155.45361 4,280 1,460 100 1,469 32 + 386 to 775 3

19.33889 -155.45235 3,675 1,480 60 1,469 32 + 433 to 656 3

19.37196 -155.49370 6,180 1,465 40 1,469 32 + 475 to 657 3

19.36258 -155.50893 6,600 1,560 70 1,507 19 + 349 to 641 3

19.31153 -155.46132 3,250 1,505 20 1,507 19 + 470 to 614 3

19.28646 -155.43131 2,200 1,360 150 1,507 19 0 393 to 993 3

19.28060 -155.49265 3,160 1,510 110 1,511 24 + 258 to 765 —

19.22904 -155.45683 1,305 1,510 60 1,511 24 + 427 to 644 —

19.26165 -155.46675 1,930 1,560 34 1,511 24 + 420 to 572 —

19.22046 -155.46249 1,190 1,470 60 1,511 24 0 433 to 661 1,2

19.22046 -155.46249 1,190 1,400 60 1,511 24 0 541 to 770 1,2

19.35027 -155.39015 2,875 1,550 50 1,530 37 + 409 to 636 3

19.43314 -155.45902 7,060 1,510 50 1,530 37 + 427 to 649 3

19.23651 -155.47197 1,190 1,561 35 1,574 25 + 419 to 573 —

19.23551 -155.47158 1,518 1,586 35 1,574 25 + 406 to 533 —

19.32433 -155.52688 6,290 1,500 30 1,622 23 + 442 to 638 3

19.29682 -155.45998 2,940 1,585 60 1,622 23 — 341 to 603 3
20

Unit label1 FID2 Age1

group

Unit name Field No. Lab No.3 Quadrangle name 

(1:24,000)

p2b10 290 2 Kapāpala Ranch flow L-91-62510 W6480 Keaiwa Reservoir

a2k11 864 2 Upper Waiākea flow HCB-83-1510 W5278 Hilo

a2k11 864 2 Upper Waiākea flow L-92-23710 USGS3463 Piihonua

a2k11 864 2 Upper Waiākea flow KUc-10110 W4344 Kulani

a2k11 864 2 Upper Waiākea flow GAM-0110 W477 Piihonua

a2k11 864 2 Upper Waiākea flow GAM-0210 W478 Piihonua

p2e14 343 2 Kauhiuhi flow L-84-02 W5458 Wood Valley

p2b15 336 2 East Wood Valley flow 2WV1C W5271 Wood Valley

p2b15 336 2 East Wood Valley flow L-90-81 W6456 Wood Valley

p2b16 540 2 Moa‘ula flow 77L-04 W3850 Pahala

p2b16 540 2 Moa‘ula flow 9P77C W5153 Pahala

p2b16 540 2 Moa‘ula flow L-91-525 W6470 Pahala

p2b16 540 2 Moa‘ula flow L-93-54510 USGS3475 Punaluu

p2b16 540 2 Moa‘ula flow L-93-59610 USGS3478 Punaluu

p2b16 540 2 Moa‘ula flow L-93-63910 WW347 Punaluu

a2a18 349 2 Kauhiuhi Maluikeao flow L-86-330 W6004 Kipuka Pakekake

p2g22 883 2 Upper Strip Road flow L-78-02 W4116 Kipuka Pakekake

p2g22 883 2 Upper Strip Road flow L-86-02 W5815 Kilauea Crater

p2g22 883 2 Upper Strip Road flow PUD-13610 W4579 Puu Ulaula

— NAS 2 — L-91-148 W6461 Wood Valley

a3a1 295 3 Red Cone flow 77L-5610 W4161 Keaiwa Reservoir

a3a1 295 3 Red Cone flow 77L-5710 W4163 Keaiwa Reservoir

a3a1 295 3 Red Cone flow L-91-18610 W6349 Keaiwa Reservoir

a3a2 889 3 Eastern Ka‘ōiki Pali flow L-77-41 W3876 Kilauea Crater

a3a2 889 3 Eastern Ka‘ōiki Pali flow L-80-81 W4831 Kilauea Crater

a3a3 637 3 Nīnole flow L-93-62610 USGS3479 Punaluu

p3e4 345 3 Cow Pasture picrite flow 77L-03 W3841 Wood Valley

p3e4 345 3 Cow Pasture picrite flow 77L-12 W3845 Wood Valley

p3e4 345 3 Cow Pasture picrite flow L-92-137 WW322 Wood Valley

p4a1 892 4 ‘Ōhaikea flow L-81-18 W5086 Kilauea Crater

ts 959 5 Southern tephra L-91-62410 W6477 Keaiwa Reservoir

ts 959 5 Southern tephra 77L-05 W3844 Wood Valley

m5a1 399 5 Halfway House flow GAM W1046 Wood Valley

m5a1 399 5 Halfway House flow 77L-05 W3844 Wood Valley

m5a1 399 5 Halfway House flow L-92-149 WW848 Wood Valley

p8e1 962 8 Palakea Flat flow KUc-17710 W4991 Kulani

p9h1 395 9 Halfway House Kīpuka flow MJ-87-C6 W6038 Wood Valley

p9h1 395 9 Halfway House Kīpuka flow L-80-163 W4821 Wood Valley

p9g2 978 9 Pu‘u‘ula‘ula flow 77L-10 W3853 Kilauea Crater

p9g2 978 9 Pu‘u‘ula‘ula flow L-80-138 W4803 Kilauea Crater

m10b1 383 10 Ka‘ū High School flow L-93-101 WW339 Pahala

m10b1 383 10 Ka‘ū High School flow L-91-50 AA7656 Pahala

m10b1 383 10 Ka‘ū High School flow L-91-680 W6482 Pahala

m10b1 383 10 Ka‘ū High School flow L-93-53310 WW343 Punaluu

Table 2. Radiocarbon ages of samples from the central-southeast flank of Mauna Loa volcano, Island of Hawai‘i, Hawaii.—Continued

[All ages are reported in radiocarbon years before present (yr B.P., before the calendar year datum of A.D. 1950). Materials dated include charcoal, roots, twigs, vegetative litter, or 

unaltered wood (rarely). See figure 1 for quadrangle locations]
21

Latitude4

(degree)

Longitude4

(degree)

 Elev

(ft)

Age5

(yr B.P.)

S.D.5

(yr)

Weighted average6

(yr B.P.) 

 S.D.6

(yr) Quality7 Age range8

 

(calendar years) Source9

19.33998 -155.52340 6,800 1,650 60 1,622 23 + 254 to 541 3

19.66731 -155.11106 660 1,740 100 1,638 32 + 78 to 535 2

19.64163 -155.16607 1,740 1,585 40 1,638 32 + 398 to 564 2

19.52973 -155.35102 6,440 1,690 70 1,638 32 + 143 to 539 2

19.67363 -155.11970 800 2,000 250 1,638 32 0 -748 to 558 2

19.67356 -155.11978 800 2,070 250 1,638 32 0 -769 to 428 2

19.36608 -155.37766 3,020 1,640 150 — — 0 71 to 661 2

19.27681 -155.47994 2,370 1,700 80 1,708 50 0 138 to 535 3

19.27368 -155.48965 2,700 1,820 80 1,708 50 + 26 to 396 3

19.18410 -155.48308 450 1,810 80 1,824 19 + 28 to 414 1,2

19.16078 -155.49543 175 1,500 70 1,824 19 0 415 to 662 2

19.18386 -155.48119 420 1,830 30 1,824 19 + 86 to 317 3

19.19656 -155.51834 1,625 1,780 40 1,824 19 + 130 to 380 3

19.18940 -155.51213 1,320 1,885 30 1,824 19 + 34 to 227 3

19.19358 -155.50552 1,340 2,030 80 1,824 19 + -348 to 130 3

19.44875 -155.43949 7,070 1,910 120 — — + -193 to 390 3

19.48293 -155.38247 6,280 1,840 60 1,993 43 + 32 to 336 1,2

19.44964 -155.34664 4,770 2,270 130 1,993 43 + -761 to -6 3

19.50618 -155.39308 7,260 2,120 70 1,993 43 + -366 to 16 2

19.30584 -155.48280 3,680 2,000 85 — — + -340 to 218 3

19.29351 -155.56723 6,760 2,000 70 2,072 37 + -195 to 131 1,2

19.29749 -155.55876 6,680 1,980 80 2,072 37 + -195 to 227 1,2

19.30734 -155.58595 7,520 2,150 50 2,072 37 + -364 to -45 3

19.45210 -155.29076 4,100 2,190 70 2,265 49 + -392 to -57 1,2

19.45208 -155.29081 4,120 2,340 70 2,265 49 + -752 to -205 2

19.16975 -155.55796 1,920 2,365 30 — — + -535 to -386 3

19.33072 -155.40527 2,600 2,950 80 2,826 32 + -1405 to -920 1,2

19.36942 -155.39613 3,550 2,880 70 2,826 32 + -1291 to -843 1,2

19.33486 -155.45218 3,540 2,890 60 2,826 32 + -1287 to -903 3

19.42062 -155.34473 4,080 3,630 80 — — + -2204 to -1758 2

19.33998 -155.52340 6,800 4,020 60 4,135 49 + -2856 to -2352 3

19.36153 -155.38214 3,020 4,340 80 4,135 49 + -3328 to -2710 3

19.36142 -155.38388 2,990 4,030 350 4,378 42 + -3515 to -1639 2

19.36307 -155.38391 3,020 4,340 80 4,378 42 + -3335 to -2705 1,2

19.36028 -155.38182 2,920 4,400 50 4,378 42 + -3327 to -2905 3

19.50935 -155.32389 5,440 7,960 110 — — + -7174 to -6593 2

19.36164 -155.38537 3,140 8,370 200 8,520 82 + -7939 to -6780 3

19.36102 -155.38548 3,050 8,550 90 8,520 82 + -7818 to -7361 1

19.41579 -155.33550 3,680 8,550 100 8,645 71 + -7865 to -7379 1,2

19.43091 -155.32599 4,000 8,740 100 8,645 71 + -8207 to -7581 2

19.20785 -155.47697 980 8,720 70 9,121 46 -8166 to -7589 3

19.20782 -155.47704 975 8,955 115 9,121 46 + -8425 to -7715 3

19.20509 -155.48798 1,160 9,960 170 9,121 46 + -10171 to -8878 3

19.21680 -155.50466 2,115 9,540 80 9,121 46 + -9213 to -8653 3
22

Unit label1 FID2 Age1

group

Unit name Field No. Lab No.3 Quadrangle name 

(1:24,000)

p10c2 742 10 Laeʻopuhili flow 9P70C1 W4419 Pahala

p10c2 742 10 Laeʻopuhili flow 78L-1810 W4201 Punaluu

ts 959 10 Southern tephra 77L-07 W3840 Kilauea Crater

p10a3 338 10 Flow 338 L-92-668 WW326 Wood Valley

NAS11 NAS 11 — L-92-606 WW325 Pahala

a11a2 388 11 Pā ́au ́au flow L-91-55 W7657 Pahala

p11b3 386 11 Meyer Camp flow L-91-46 W6423 Pahala

a13b2 384 13 Flow 384 L-91-564R WW240 Pahala

a13b2 384 13 Flow 384 L-91-54810 W6471 Punaluu

a13b2 384 13 Flow 384 L-92-582 USGS3471 Pahala

NAS11 NAS 13 — L-92-588 USGS3473 Pahala

NAS11 NAS 13 — L-92-576 USGS3470 Pahala

a13f3 735 13 Lava flow of Hi‘onamoa Gulch L-91-55510 WW321 Punaluu

z13a4 389 13 Pāhala Ash L-92-582D USGS3472 Pahala

1See table 3 (sheet 1) for explanation of unit labels and definition of age groups.

2Unique, three-digit flow identification number assigned to each mapped surface-flow unit correlates with database (https://doi.org/10.3133/sim2932B).

3

Initial letter(s) identifies analytical laboratory: AA, University of Arizona, Tucson, Ariz.; SUERC, NERC radiocarbon laboratory, Kilbride, Scotland, UK; 

USGS, U.S. Geological Survey 14C laboratory, Menlo Park, Calif.; W, U.S. Geological Survey 14C laboratory, Reston, Va. Initial letter(s) for Accelerator Mass 

Spectrometer (AMS) ages: A, WW, SUERC.

4

Projection: decimal degrees. Datum: WGS84.

5

Calibrated ages are for two standard deviations. 

6

Weighted avg., each age is weighted by the inverse of its variance before averaging (for example, Taylor 1982). A variance is reported as one standard 

deviation, in years.

7

Quality: +, age considered meaningful; 0, age probably meaningful but accuracy may be poorer than indicated by the reported precision. 

8

Each age was calibrated to calendar years using CALIB 6.0 Radiocarbon Calibration Program (Stuiver and others, 2005); calibrated ages are for two 

standard deviations. Entire age range of calendar ages is possible for a given sample. Unspecified ages, A.D.; negative (-) ages, B.C.

9

Sources: 1, Kelley and others, 1979; 2, Rubin and others, 1987; 3, this study.

10Radiocarbon sample collected outside of mapped area: Kulani, Piihonua, and Puu Ulaula quadrangles (SIM 2932–A); Punaluu quadrangle (SIM 2932–C), 

and Keaiwa Reservoir quadrangle (SIM 2932–D).

11NAS, flows not found at surface are exposed in drainages, fault scarps, and (or) sea cliffs.

12NAC, not able to calibrate 14C age because too old for CALIB program.

Table 2. Radiocarbon ages of samples from the central-southeast flank of Mauna Loa volcano, Island of Hawai‘i, Hawaii.—Continued

[All ages are reported in radiocarbon years before present (yr B.P., before the calendar year datum of A.D. 1950). Materials dated include charcoal, roots, twigs, vegetative litter, or 

unaltered wood (rarely). See figure 1 for quadrangle locations]
23

Latitude4

(degree)

Longitude4

(degree)

 Elev

(ft)

Age5

(yr B.P.)

S.D.5

(yr)

Weighted average6

(yr B.P.) 

 S.D.6

(yr) Quality7 Age range8

 

(calendar years) Source9

19.15966 -155.49475 210 9,300 130 9,218 79 + -9118 to -8261 2

19.20450 -155.53528 2,140 9,170 100 9,218 79 + -8694 to -8227 1,2

19.41515 -155.34106 3,750 9,500 140 — — + -9252 to -8471 1,2

19.28410 -155.42982 2,120 9,680 70 — — + -9279 to -8830 3

19.23768 -155.48886 1,980 10,010 70 — — + -9858 to -9301 3

19.21949 -155.48103 1,380 10,030 85 — — + -10009 to -9306 3

19.21947 -155.48614 1,460 10,600 150 — — + -10908 to -10151 3

19.19938 -155.48648 990 25,000 460 25,768 188 + NAC12 3

19.20977 -155.49981 1,610 25,570 600 25,768 188 — NAC12 3

19.18879 -155.48278 575 25,970 220 25,768 188 + NAC12 3

19.20514 -155.49645 1,400 26,450 120 26,532 88 + NAC12 3

19.20026 -155.48893 1,060 26,630 130 26,532 88 + NAC12 3

19.20966 -155.49983 1,605 28,140 590 — — + NAC12 3

19.18873 -155.48278 575 31,020 310 — — + NAC12 3