Any use of trade, product, or firm names in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://dx.doi.org/10.3133/pp1812

Suggested citation: Hildreth, Wes, and Fierstein, Judy, 2016, Eruptive history of Mammoth 

Mountain and its mafic periphery: U.S. Geological Survey Professional Paper 1812, 128 p., 

2 plates, scale 1:24,000, http://dx.doi.org/10.3133/pp1812.

ISSN 1044-9612 (print)

ISSN 2330-7102 (online)

http://dx.doi.org/10.3133/pp1812

Eruptive History of Mammoth Mountain and its Mafic Periphery, California

By

Wes Hildreth and Judy Fierstein

2016

U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1812

Plate 2 of 2

Pamphlet accompanies map

LIST OF MAP UNITS

[Uniform black stipple indicates units partly or wholly pyroclastic. See Description of Map Units 

(in pamphlet) for complete unit descriptions]

SURFICIAL DEPOSITS

Phreatic ejecta (late Holocene)

Pumice deposits (late Holocene)

Rock glacier deposits (Holocene)

Spring deposits (Holocene and late Pleistocene)

Alluvium, undivided (Holocene and late Pleistocene) 

Alluvial fan deposits (Holocene and late Pleistocene)

Older alluvium (late and middle Pleistocene)

Precaldera alluvium (early Pleistocene)

Rockfall avalanche deposits (Holocene and late Pleistocene)

Surficial deposits, undivided (Holocene and late Pleistocene)

Explosion breccia deposit of Bailey (late Pleistocene)

Diamict of lower Mammoth Creek (late Pleistocene)

Sandstone of Long Valley Lake (middle Pleistocene)

Siltstone of Long Valley Lake (middle Pleistocene)

GLACIAL DEPOSITS

Till of Cold Water Canyon (late Pleistocene)

Till of Dry Creek (late Pleistocene)

Till derived from Lakes Basin (late Pleistocene)

Till derived from Mammoth Mountain (late Pleistocene)

Undivided glacial deposits (late and middle Pleistocene)

Casa Diablo Till (latest middle Pleistocene)

Sherwin Till (late early Pleistocene)

QUATERNARY VOLCANIC ROCKS

SAN JOAQUIN

Trachyandesite of Cone 2962 (late Pleistocene)

Trachyandesite of Pumice Butte (middle Pleistocene)

Trachybasalt west of Deer Creek (middle Pleistocene)

Basalt of Red Cones (Holocene)

Trachydacite of Rainbow Falls (late Pleistocene)

Basaltic trachyandesite of Devils Postpile (late Pleistocene)

Basaltic trachyandesite of upper Soda Springs (late Pleistocene)

MAMMOTH MOUNTAIN

Trachyandesite of Mammoth Pass (late Pleistocene)

Trachydacite of Bottomless Pit (late Pleistocene)

Trachydacite of lower Dragons Back (late Pleistocene)

Trachydacite of upper Dragons Back (late Pleistocene)

Trachydacite of Face Lift (late Pleistocene) 

Trachydacite of Gold Rush Express (late Pleistocene)

Trachydacite of Lincoln Peak (late Pleistocene)

Trachydacite of Main Lodge Coulee (late Pleistocene)

Trachydacite of McCoy Station (late Pleistocene)

Trachydacite north of Horseshoe Lake (late Pleistocene)

Trachydacite of North Knob (late Pleistocene)

Trachydacite of Old Mammoth (late Pleistocene)

Trachydacite of upper Reds Creek (late Pleistocene)

Trachydacite of South Summit Dome (late Pleistocene)

Trachydacite of Skyline Dome (late Pleistocene)

Trachydacite of Mammoth Mountain summit (late Pleistocene)

Trachydacite of Twin Lakes outlet (late Pleistocene)

Trachydacite of White Bark Ridge (late Pleistocene)

Trachydacite of Dome 2861 (late Pleistocene)

Trachydacite of Dome 2781 (late Pleistocene)

Alkalic rhyodacite of Canyon Express (late Pleistocene)

Alkalic rhyodacite pumice fall of Highway 203 (late Pleistocene)

Alkalic rhyodacite of Mammoth Mountain fumarole (late Pleistocene)

Alkalic rhyodacite of Reds Creek (late Pleistocene)

Alkalic rhyodacite of Quicksilver ski run (late Pleistocene)

Alkalic rhyodacite of Solitude ski run (late Pleistocene)

SOUTH MOAT AND LAKES BASIN

Trachyandesite of McLeod Lake (late Pleistocene)

Trachyandesite of Shady Rest Campground (middle Pleistocene)

Basalt of Casa Diablo Hot Springs (late Pleistocene) 

Basalt east of Dry Creek (late Pleistocene)

Basalt of Fish Hatchery (late Pleistocene)

Basalt of Horseshoe Lake (late Pleistocene)

Basalt of Mammoth Crest (late Pleistocene)

Trachybasalt of Sherwin Creek Road (middle Pleistocene)

Basalt of Sawmill Cutoff (middle Pleistocene)

Trachybasalt of Shady Rest (late Pleistocene)

Basaltic trachyandesite of Canyon Lodge (middle Pleistocene)

Basaltic trachyandesite of Knolls Vista (middle Pleistocene)

Basaltic trachyandesite of lower Laurel Creek (middle Pleistocene)

Basaltic trachyandesite of Mammoth Creek (middle Pleistocene)

Basaltic trachyandesite of Sawmill Cutoff (middle Pleistocene)

WEST MOAT

Trachyandesite of Inyo Craters (late middle Pleistocene)

Trachybasalt of Arcularius Ranch (late Pleistocene)

Trachybasalt south of Crater Flat (middle Pleistocene)

Trachybasalt northeast of Minaret Summit (late Pleistocene)

Trachydacite of Dry Creek (late Pleistocene)

Trachydacites of northwest moat (late Pleistocene) 

Basaltic trachyandesite south of Crestview (late Pleistocene)

Basaltic trachyandesite of Deer Mountain (late or middle Pleistocene)

Basaltic trachyandesite northeast of Deadman Pass (late Pleistocene)

Mafic pyroclastic deposit of Inyo Craters (Holocene or late Pleistocene)

Basaltic trachyandesite northwest of Dry Creek (late Pleistocene)

Basaltic trachyandesite of Owens River Road (late Pleistocene)

Basaltic trachyandesite scoria southeast of Dry Creek (late Pleistocene)

Basaltic andesite of Scenic Loop Road junction (late or middle Pleistocene)

LONG VALLEY AND INYO CHAIN

Bishop Tuff (middle Pleistocene)

Rhyolite of Cratered Dome (Holocene)

Rhyolite of caldera wall (Holocene)

Rhyolite of Dry Creek Dome (late Pleistocene)

Rhyolite of Deer Mountain (late Pleistocene)

Early rhyolite of Bailey (middle Pleistocene)

Lookout Mountain subunit

Tuff of Little Antelope Valley subunit

Pumice Cone 2368 subunit

Tuff east of Casa Diablo subunit

Rhyolite of Hot Creek flow (middle Pleistocene)

Rhyolite and rhyodacite of Inyo chain (1350 C.E.)

Rhyolite of Mammoth Knolls (late Pleistocene)

Rhyolite of north-central chain (middle Pleistocene)

Rhyolite of North Deadman Creek Dome (Holocene) 

Rhyolite of West Moat Coulee (middle Pleistocene)

TERTIARY VOLCANIC ROCKS

SAN JOAQUIN AND SIERRA NEVADA

Trachyandesite of Crater Creek (Pliocene)

Trachyandesite of San Joaquin River (Miocene)

Trachybasalt south of Lost Dog Lake (Pliocene)

Trachybasalt east of Pond Lily Lake (Pliocene)

Basalt of The Buttresses (Pliocene)

Basaltic trachyandesite west of Cabin Lake (Pliocene?)

Basaltic trachyandesite south of Upper Crater Meadow (Pliocene)

Basaltic trachyandesite west of Crater Creek (Pliocene)

Basaltic trachyandesite of Emerald Lake (Pliocene?)

Basaltic trachyandesite south of Deer Creek (Pliocene?)

Basaltic trachyandesite west of Castle Lake (Pliocene?)

LAKES BASIN

Trachybasalt of Mammoth Mine (Pliocene) 

Basalt of Red Mountain (Pliocene)

Basaltic trachyandesite of Mammoth Crest (Pliocene)

WEST WALL

Trachydacite pyroclastic-density-current deposit of Deadman Pass (Pliocene)

Trachybasalt of Deadman Pass (Pliocene)

Trachydacite of Dome 3321 (Pliocene)

Trachydacite block-and-ash-flow deposits of San Joaquin Ridge (Pliocene)

Trachydacite complex of upper Deadman Creek (Pliocene)

Trachydacite of White Wing Mountain (Pliocene)

Trachydacite of Dome 2965 (Pliocene) 

Basaltic trachyandesite of White Wing Mountain (Pliocene?)

NORTH WALL

Trachyandesite east of Crestview (Pliocene)

Trachyandesite north of White Wing Camp (Pliocene) 

Basalt east of Big Springs (Miocene)

Trachybasalt and basaltic trachyandesite of Cone 8478 (Pliocene)

Trachydacite of Dome 7835 (Pliocene)

Trachydacite of Dome 8325 (Pliocene)

Basaltic trachyandesite of Crestview (Pliocene)

Basaltic trachyandesite west and east of Obsidian flow (Pliocene)

Rhyolite tuff of Alpers Canyon (Miocene)

SOUTH WALL

Trachydacite of Laurel Mountain (Pliocene)

PRE-CENOZOIC BASEMENT ROCKS

[Listed in order of increasing age]

Mono Creek Granite (Late Cretaceous)

Round Valley Peak Granodiorite (Late Cretaceous)

Granite of June Lake (Late Cretaceous)

Granite of Big Springs (Jurassic?)

Granodiorite northeast of Minaret Summit (Mesozoic)

Metavolcanic rocks of Ritter Range pendant (Mesozoic)

Metasedimentary rocks of Mount Morrison pendant (Paleozoic)

EXPLANATION OF MAP SYMBOLS

Contact—Long-dashed where approximately located; short-dashed where 

inferred; dotted where concealed; dash-dot line for internal contact within 

unit

Fault—Bar and ball on downthrown side; dashed where approximately located; 

dotted where concealed

Volcanic craters and partial crater rims—Hachures point inward

Volcanic fissure vent

Surficial rift or fissure on lava flow (not a vent)

Lava flow direction

Moraine crests

Strike and dip of ejecta, stacks of thin lava flows, and sandstone

Inclined

Vertical

Horizontal

Volcanic vent (other than craters and fissures)

Rootless volcanic vent (other than craters and fissures)

25

pe

p

rg

sd

al

fan

oal

pal

av

s

eb

lmd

ss

st

gcc

gdc

glb

gmm

gud

gcd

gst

a62

apb

bdc

brc

drf

mdp

mss

amp

dbp

ddl

ddu

dfl

dgr

dlp

dml

dms

dnh

dnk

dom

drc

dsd

dsk

dsu

dtl

dwr

d61

d81

rce

rfp

rmf

rrc

rsq

rss

aml

asr

bcd

bed

bfh

bhl

bmc

bsc

bsm

bsr

mcl

mkv

mlc

mmc

msc

aic

bar' bar

bcf

bmn' bmn

ddc

dnw

mcv

mdm

mdn' mdn

mic

mnd

mor

msd

msj

rbt

rcd

rcw

rdc

rdm

rer

rlm

rtav

r68

rtcd

rhc' rhc

ric

rmk

rnc

rnd

rwm

Tacc

Tasj

Tbld

Tbpl

Tbtb

Taec

Tmcl

Trac

Tmcm

Tmcw

Tmel

Tmsd

Tmwc

Tbmm

Tbrm

Tmcr

Tdpd

Tbdp

Tdsd

Tdsj

Tdud

Tdww

Td65

Tmww

Taww

Tbbs

Tb84

Td78

Td83

Tmcv

Tmwo

Tdlm

Kmo

Krv' Krv

Kjl

Jbs

gd

mv

ms

11.7 ka

126 ka

788 ka

5.3 Ma

2.58 Ma

65.5 Ma

251 Ma

Tacc

Tasj

Tbld

Tbpl

Tbtb

Tmcl Tmcm

Tmel Tmcw

Tmsd

Tmwc

Tdpd

Tdsd

Tdsj

Tbdp 

Tdud

Tdww Td65

Tmww

bcd bed

bfh

bhl

bmc

bsc

bsm

bsr

mcl

mkv

mlc

mmc

msc

aml

asr

bcf

bmn

ddc

dnw

mcv

mdn' mdn

mdm

mic

mor

mnd

msj

msd

aic

bar' bar

dbp

ddl

ddu

dfl

dgr

dms

dlp

dml

dnk

dom

drc

dsd

dnh

dsk

dtl

dsu

d61

dwr

d81

rce rfp

rmf

rrc

rsq

rss

amp

rbt

rcd rcw

rdm

rdc

rlm

rtav

r68

rtcd

rer

rhc rhc'

ric

rmk

rnd

rnc

rwm

bdc

brc

drf

mdp

mss

a62

apb

sd

pe

p rg

rg'

oal

pal

fan

al

av

lmd

st ss

s

eb

gcc gdc glb gmm

gud

gst

Tmcr

Tbmm Tbrm

Taec

Taww Tb84

Tbbs

Td83 Td78

Tmwo

Trac

Tmcv

Tdlm

Jbs

Kmo Kjl Krv' Krv

ms

mv

gd

gcd

Middle

Pleistocene

Early

Pleistocene

Pliocene

Miocene

MESOZOIC

CENOZOIC

PALEOZOIC

Late

Pleistocene

Holocene

(1350 C.E.)

CORRELATION OF MAP UNITS

[Extended boxes indicate known age ranges for long-lived units. See Description of Map Units (in pamphlet) for specific unit age assignments]

AGE SURFICIAL DEPOSITS GLACIAL DEPOSITS QUATERNARY VOLCANIC ROCKS

SAN JOAQUIN AND SIERRA NEVADA WEST CALDERA WALL

SAN JOAQUIN MAMMOTH MOUNTAIN SOUTH MOAT AND LAKES BASIN WEST MOAT LONG VALLEY AND INYO SUITES

LAKES BASIN NORTH CALDERA WALL SOUTH CALDERA WALL

PRE-CENOZOIC BASEMENT ROCKS

TERTIARY VOLCANIC ROCKS

Basaltic scoria cone 5 km south-southwest of Mammoth Mountain summit. The cone is 120 m high and 500 m wide and has a twin cone just south of it (see fig. 10). Named Red Cones, the pair 

erupted concurrently about 8,000 years ago, representing the most recent magmatic eruption of the entire Mammoth system. Both cones are breached to the west, where they jointly formed an 

agglutinate fan, which fed a lava field that extends 2.5 km southwest. See unit brc in Description of Map Units.
Any use of trade, product, or firm names in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://dx.doi.org/10.3133/pp1812

Suggested citation: Hildreth, Wes, and Fierstein, Judy, 2016, Eruptive history of Mammoth 

Mountain and its mafic periphery: U.S. Geological Survey Professional Paper 1812, 128 p., 

2 plates, scale 1:24,000, http://dx.doi.org/10.3133/pp1812.

ISSN 1044-9612 (print)

ISSN 2330-7102 (online)

http://dx.doi.org/10.3133/pp1812

Eruptive History of Mammoth Mountain and its Mafic Periphery, California

By

Wes Hildreth and Judy Fierstein

2016

U.S. Department of the Interior

U.S. Geological Survey

Professional Paper 1812

Plate 2 of 2

Pamphlet accompanies map

LIST OF MAP UNITS

[Uniform black stipple indicates units partly or wholly pyroclastic. See Description of Map Units 

(in pamphlet) for complete unit descriptions]

SURFICIAL DEPOSITS

Phreatic ejecta (late Holocene)

Pumice deposits (late Holocene)

Rock glacier deposits (Holocene)

Spring deposits (Holocene and late Pleistocene)

Alluvium, undivided (Holocene and late Pleistocene) 

Alluvial fan deposits (Holocene and late Pleistocene)

Older alluvium (late and middle Pleistocene)

Precaldera alluvium (early Pleistocene)

Rockfall avalanche deposits (Holocene and late Pleistocene)

Surficial deposits, undivided (Holocene and late Pleistocene)

Explosion breccia deposit of Bailey (late Pleistocene)

Diamict of lower Mammoth Creek (late Pleistocene)

Sandstone of Long Valley Lake (middle Pleistocene)

Siltstone of Long Valley Lake (middle Pleistocene)

GLACIAL DEPOSITS

Till of Cold Water Canyon (late Pleistocene)

Till of Dry Creek (late Pleistocene)

Till derived from Lakes Basin (late Pleistocene)

Till derived from Mammoth Mountain (late Pleistocene)

Undivided glacial deposits (late and middle Pleistocene)

Casa Diablo Till (latest middle Pleistocene)

Sherwin Till (late early Pleistocene)

QUATERNARY VOLCANIC ROCKS

SAN JOAQUIN

Trachyandesite of Cone 2962 (late Pleistocene)

Trachyandesite of Pumice Butte (middle Pleistocene)

Trachybasalt west of Deer Creek (middle Pleistocene)

Basalt of Red Cones (Holocene)

Trachydacite of Rainbow Falls (late Pleistocene)

Basaltic trachyandesite of Devils Postpile (late Pleistocene)

Basaltic trachyandesite of upper Soda Springs (late Pleistocene)

MAMMOTH MOUNTAIN

Trachyandesite of Mammoth Pass (late Pleistocene)

Trachydacite of Bottomless Pit (late Pleistocene)

Trachydacite of lower Dragons Back (late Pleistocene)

Trachydacite of upper Dragons Back (late Pleistocene)

Trachydacite of Face Lift (late Pleistocene) 

Trachydacite of Gold Rush Express (late Pleistocene)

Trachydacite of Lincoln Peak (late Pleistocene)

Trachydacite of Main Lodge Coulee (late Pleistocene)

Trachydacite of McCoy Station (late Pleistocene)

Trachydacite north of Horseshoe Lake (late Pleistocene)

Trachydacite of North Knob (late Pleistocene)

Trachydacite of Old Mammoth (late Pleistocene)

Trachydacite of upper Reds Creek (late Pleistocene)

Trachydacite of South Summit Dome (late Pleistocene)

Trachydacite of Skyline Dome (late Pleistocene)

Trachydacite of Mammoth Mountain summit (late Pleistocene)

Trachydacite of Twin Lakes outlet (late Pleistocene)

Trachydacite of White Bark Ridge (late Pleistocene)

Trachydacite of Dome 2861 (late Pleistocene)

Trachydacite of Dome 2781 (late Pleistocene)

Alkalic rhyodacite of Canyon Express (late Pleistocene)

Alkalic rhyodacite pumice fall of Highway 203 (late Pleistocene)

Alkalic rhyodacite of Mammoth Mountain fumarole (late Pleistocene)

Alkalic rhyodacite of Reds Creek (late Pleistocene)

Alkalic rhyodacite of Quicksilver ski run (late Pleistocene)

Alkalic rhyodacite of Solitude ski run (late Pleistocene)

SOUTH MOAT AND LAKES BASIN

Trachyandesite of McLeod Lake (late Pleistocene)

Trachyandesite of Shady Rest Campground (middle Pleistocene)

Basalt of Casa Diablo Hot Springs (late Pleistocene) 

Basalt east of Dry Creek (late Pleistocene)

Basalt of Fish Hatchery (late Pleistocene)

Basalt of Horseshoe Lake (late Pleistocene)

Basalt of Mammoth Crest (late Pleistocene)

Trachybasalt of Sherwin Creek Road (middle Pleistocene)

Basalt of Sawmill Cutoff (middle Pleistocene)

Trachybasalt of Shady Rest (late Pleistocene)

Basaltic trachyandesite of Canyon Lodge (middle Pleistocene)

Basaltic trachyandesite of Knolls Vista (middle Pleistocene)

Basaltic trachyandesite of lower Laurel Creek (middle Pleistocene)

Basaltic trachyandesite of Mammoth Creek (middle Pleistocene)

Basaltic trachyandesite of Sawmill Cutoff (middle Pleistocene)

WEST MOAT

Trachyandesite of Inyo Craters (late middle Pleistocene)

Trachybasalt of Arcularius Ranch (late Pleistocene)

Trachybasalt south of Crater Flat (middle Pleistocene)

Trachybasalt northeast of Minaret Summit (late Pleistocene)

Trachydacite of Dry Creek (late Pleistocene)

Trachydacites of northwest moat (late Pleistocene) 

Basaltic trachyandesite south of Crestview (late Pleistocene)

Basaltic trachyandesite of Deer Mountain (late or middle Pleistocene)

Basaltic trachyandesite northeast of Deadman Pass (late Pleistocene)

Mafic pyroclastic deposit of Inyo Craters (Holocene or late Pleistocene)

Basaltic trachyandesite northwest of Dry Creek (late Pleistocene)

Basaltic trachyandesite of Owens River Road (late Pleistocene)

Basaltic trachyandesite scoria southeast of Dry Creek (late Pleistocene)

Basaltic andesite of Scenic Loop Road junction (late or middle Pleistocene)

LONG VALLEY AND INYO CHAIN

Bishop Tuff (middle Pleistocene)

Rhyolite of Cratered Dome (Holocene)

Rhyolite of caldera wall (Holocene)

Rhyolite of Dry Creek Dome (late Pleistocene)

Rhyolite of Deer Mountain (late Pleistocene)

Early rhyolite of Bailey (middle Pleistocene)

Lookout Mountain subunit

Tuff of Little Antelope Valley subunit

Pumice Cone 2368 subunit

Tuff east of Casa Diablo subunit

Rhyolite of Hot Creek flow (middle Pleistocene)

Rhyolite and rhyodacite of Inyo chain (1350 C.E.)

Rhyolite of Mammoth Knolls (late Pleistocene)

Rhyolite of north-central chain (middle Pleistocene)

Rhyolite of North Deadman Creek Dome (Holocene) 

Rhyolite of West Moat Coulee (middle Pleistocene)

TERTIARY VOLCANIC ROCKS

SAN JOAQUIN AND SIERRA NEVADA

Trachyandesite of Crater Creek (Pliocene)

Trachyandesite of San Joaquin River (Miocene)

Trachybasalt south of Lost Dog Lake (Pliocene)

Trachybasalt east of Pond Lily Lake (Pliocene)

Basalt of The Buttresses (Pliocene)

Basaltic trachyandesite west of Cabin Lake (Pliocene?)

Basaltic trachyandesite south of Upper Crater Meadow (Pliocene)

Basaltic trachyandesite west of Crater Creek (Pliocene)

Basaltic trachyandesite of Emerald Lake (Pliocene?)

Basaltic trachyandesite south of Deer Creek (Pliocene?)

Basaltic trachyandesite west of Castle Lake (Pliocene?)

LAKES BASIN

Trachybasalt of Mammoth Mine (Pliocene) 

Basalt of Red Mountain (Pliocene)

Basaltic trachyandesite of Mammoth Crest (Pliocene)

WEST WALL

Trachydacite pyroclastic-density-current deposit of Deadman Pass (Pliocene)

Trachybasalt of Deadman Pass (Pliocene)

Trachydacite of Dome 3321 (Pliocene)

Trachydacite block-and-ash-flow deposits of San Joaquin Ridge (Pliocene)

Trachydacite complex of upper Deadman Creek (Pliocene)

Trachydacite of White Wing Mountain (Pliocene)

Trachydacite of Dome 2965 (Pliocene) 

Basaltic trachyandesite of White Wing Mountain (Pliocene?)

NORTH WALL

Trachyandesite east of Crestview (Pliocene)

Trachyandesite north of White Wing Camp (Pliocene) 

Basalt east of Big Springs (Miocene)

Trachybasalt and basaltic trachyandesite of Cone 8478 (Pliocene)

Trachydacite of Dome 7835 (Pliocene)

Trachydacite of Dome 8325 (Pliocene)

Basaltic trachyandesite of Crestview (Pliocene)

Basaltic trachyandesite west and east of Obsidian flow (Pliocene)

Rhyolite tuff of Alpers Canyon (Miocene)

SOUTH WALL

Trachydacite of Laurel Mountain (Pliocene)

PRE-CENOZOIC BASEMENT ROCKS

[Listed in order of increasing age]

Mono Creek Granite (Late Cretaceous)

Round Valley Peak Granodiorite (Late Cretaceous)

Granite of June Lake (Late Cretaceous)

Granite of Big Springs (Jurassic?)

Granodiorite northeast of Minaret Summit (Mesozoic)

Metavolcanic rocks of Ritter Range pendant (Mesozoic)

Metasedimentary rocks of Mount Morrison pendant (Paleozoic)

EXPLANATION OF MAP SYMBOLS

Contact—Long-dashed where approximately located; short-dashed where 

inferred; dotted where concealed; dash-dot line for internal contact within 

unit

Fault—Bar and ball on downthrown side; dashed where approximately located; 

dotted where concealed

Volcanic craters and partial crater rims—Hachures point inward

Volcanic fissure vent

Surficial rift or fissure on lava flow (not a vent)

Lava flow direction

Moraine crests

Strike and dip of ejecta, stacks of thin lava flows, and sandstone

Inclined

Vertical

Horizontal

Volcanic vent (other than craters and fissures)

Rootless volcanic vent (other than craters and fissures)

25

pe

p

rg

sd

al

fan

oal

pal

av

s

eb

lmd

ss

st

gcc

gdc

glb

gmm

gud

gcd

gst

a62

apb

bdc

brc

drf

mdp

mss

amp

dbp

ddl

ddu

dfl

dgr

dlp

dml

dms

dnh

dnk

dom

drc

dsd

dsk

dsu

dtl

dwr

d61

d81

rce

rfp

rmf

rrc

rsq

rss

aml

asr

bcd

bed

bfh

bhl

bmc

bsc

bsm

bsr

mcl

mkv

mlc

mmc

msc

aic

bar' bar

bcf

bmn' bmn

ddc

dnw

mcv

mdm

mdn' mdn

mic

mnd

mor

msd

msj

rbt

rcd

rcw

rdc

rdm

rer

rlm

rtav

r68

rtcd

rhc' rhc

ric

rmk

rnc

rnd

rwm

Tacc

Tasj

Tbld

Tbpl

Tbtb

Taec

Tmcl

Trac

Tmcm

Tmcw

Tmel

Tmsd

Tmwc

Tbmm

Tbrm

Tmcr

Tdpd

Tbdp

Tdsd

Tdsj

Tdud

Tdww

Td65

Tmww

Taww

Tbbs

Tb84

Td78

Td83

Tmcv

Tmwo

Tdlm

Kmo

Krv' Krv

Kjl

Jbs

gd

mv

ms

11.7 ka

126 ka

788 ka

5.3 Ma

2.58 Ma

65.5 Ma

251 Ma

Tacc

Tasj

Tbld

Tbpl

Tbtb

Tmcl Tmcm

Tmel Tmcw

Tmsd

Tmwc

Tdpd

Tdsd

Tdsj

Tbdp 

Tdud

Tdww Td65

Tmww

bcd bed

bfh

bhl

bmc

bsc

bsm

bsr

mcl

mkv

mlc

mmc

msc

aml

asr

bcf

bmn

ddc

dnw

mcv

mdn' mdn

mdm

mic

mor

mnd

msj

msd

aic

bar' bar

dbp

ddl

ddu

dfl

dgr

dms

dlp

dml

dnk

dom

drc

dsd

dnh

dsk

dtl

dsu

d61

dwr

d81

rce rfp

rmf

rrc

rsq

rss

amp

rbt

rcd rcw

rdm

rdc

rlm

rtav

r68

rtcd

rer

rhc rhc'

ric

rmk

rnd

rnc

rwm

bdc

brc

drf

mdp

mss

a62

apb

sd

pe

p rg

rg'

oal

pal

fan

al

av

lmd

st ss

s

eb

gcc gdc glb gmm

gud

gst

Tmcr

Tbmm Tbrm

Taec

Taww Tb84

Tbbs

Td83 Td78

Tmwo

Trac

Tmcv

Tdlm

Jbs

Kmo Kjl Krv' Krv

ms

mv

gd

gcd

Middle

Pleistocene

Early

Pleistocene

Pliocene

Miocene

MESOZOIC

CENOZOIC

PALEOZOIC

Late

Pleistocene

Holocene

(1350 C.E.)

CORRELATION OF MAP UNITS

[Extended boxes indicate known age ranges for long-lived units. See Description of Map Units (in pamphlet) for specific unit age assignments]

AGE SURFICIAL DEPOSITS GLACIAL DEPOSITS QUATERNARY VOLCANIC ROCKS

SAN JOAQUIN AND SIERRA NEVADA WEST CALDERA WALL

SAN JOAQUIN MAMMOTH MOUNTAIN SOUTH MOAT AND LAKES BASIN WEST MOAT LONG VALLEY AND INYO SUITES

LAKES BASIN NORTH CALDERA WALL SOUTH CALDERA WALL

PRE-CENOZOIC BASEMENT ROCKS

TERTIARY VOLCANIC ROCKS

Basaltic scoria cone 5 km south-southwest of Mammoth Mountain summit. The cone is 120 m high and 500 m wide and has a twin cone just south of it (see fig. 10). Named Red Cones, the pair 

erupted concurrently about 8,000 years ago, representing the most recent magmatic eruption of the entire Mammoth system. Both cones are breached to the west, where they jointly formed an 

agglutinate fan, which fed a lava field that extends 2.5 km southwest. See unit brc in Description of Map Units.