220±67

MZI-11A

bw

bwp

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boe

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bop

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ao

bow

bbc

bck

bc

bcp

blcp

bsc

bscp

bf

bfi

bu

bui

bx

bxi

at

atg

ati

bxn

bxni

bbi

bbp

bcw

bwc

bwcp

acc

accp

bln

bcc

bcn

boi

bbf

bfp

bup

bxp

baw

bwci

bac

atc

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b

al

sl

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ls

g

s

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aw

awb

awp

amc

amcb

ae

apc

apcb

cf

cb

cd

cw

cu

cp

rh

rhv

rs

rhp

rhc

ab

abt

rbb

abp

re

rec

rep

mw

rev

dvb

dv

als

apu

atw

asb

ad

dwf

dwv

dwp

ah

dlp

agc

bh

bhp

bhi

dc

dcp

bs

asl

arw

aww

apw

bsp

abl

dsbp

alu

dpt

all

ar

amv

ags

am

dcn

ag

dg

aa

aai

ac

dm

arv

dr

dpn

awe

af

ak

db

ams

ds

dsf

dsp

dcc

apn

apni

asc

ascp

acr

acrp

bcsp

bcnp

alb

albp

bsw

bmc

bmcp

bsr

bsrp

bt

btp

rpb

rpbv

rcs

rsc

bep

aq

aaf

bdp

bap

dw

as

acs

acsp

blp

baf

rcc

dsc

adsi

dd

asw

dpe

dsb

bwn

bwnp

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buc

buci

dcnp

LIST OF MAP UNITS

[Units are shown on geologic map (sheet 1) and (or) on bedrock map (sheet 3) and panoramas 

(sheet 4). See DESCRIPTION OF MAP UNITS (pamphlet) for specific age determinations. Unit 

colors for igneous rocks are intended to reflect composition, nature of material, and age (a color 

may be used for different units): basalt, purple; basaltic andesite, blue; andesite, green; borderline 

andesite/basaltic andesite, blue-green; dacite, yellow or orange; rhyodacite, pink or red. Generally, 

darker colors denote younger units. Within a unit, intrusive rocks (labels end in “i”) are darkest, 

lava flows intermediate, and pyroclastic rocks (labels end in “p”) lightest. Some unit exposures on 

the printed map are too small to distinguish the color for unit identification. These are labeled 

where possible, and unlabeled units are attributed in the database]

SEDIMENTARY DEPOSITS

Alluvium (Holocene)

Sediment gravity-flow deposits (Holocene)

Talus (Holocene and Pleistocene)

Landslide deposits (Holocene)

Glacial deposits, undivided (Pleistocene)

Sedimentary deposits, undivided (late and middle Pleistocene)

VOLCANIC ROCKS

Regional Volcanism, Northwest

Basaltic andesite northwest of Williams Crater (late Pleistocene)

Lava

Pyroclastic

Basaltic andesite of Williams Crater (late Pleistocene)

Lava

Pyroclastic

Basaltic andesite northwest of Red Cone (late Pleistocene)

Basaltic andesite of Red Cone (late Pleistocene)

Lava

Pyroclastic

Basalt east of Oasis Butte (late Pleistocene)

Andesite of Timber Crater (late or middle Pleistocene)

Basaltic andesite of Oasis Butte (middle Pleistocene)

Intrusive

Lava

Pyroclastic

Basaltic andesite north of Red Cone (middle? Pleistocene)

Andesite southwest of Oasis Butte (middle Pleistocene)

Basaltic andesite west of Oasis Butte (middle? Pleistocene)

Basaltic andesite of Bert Creek (early Pleistocene)

Mudflow

Lava

Basaltic andesite north of Crater Creek (early Pleistocene)

Regional Volcanism, Southwest

Basalt of Castle Point (early Holocene)

Lava

Pyroclastic

Basaltic andesite north of Little Castle Creek (late Pleistocene)

Basaltic andesite of Scoria Cone (late Pleistocene)

Lava

Pyroclastic

Basaltic andesite northwest of Pumice Flat (late Pleistocene)

Lava

Intrusive

Pyroclastic

Basaltic andesite of Union Peak (middle Pleistocene)

Lava

Intrusive

Pyroclastic

Basaltic andesite of Whitehorse Bluff (middle Pleistocene)

Lava

Intrusive

Pyroclastic

Andesite of Arant Point (middle Pleistocene)

Lava

Vitric

Intrusive

Basalt northwest of Whitehorse Bluff (middle? Pleistocene)

Lava

Intrusive

Basaltic andesite west of Arant Point (middle Pleistocene)

Basaltic andesite west of Bear Bluff (middle? Pleistocene)

Intrusive

Pyroclastic

Basaltic andesite west of Mazama Campground (middle? Pleistocene)

Basaltic andesite of Whitehorse Creek (middle? Pleistocene)

Lava

Intrusive

Pyroclastic

Andesite north of Castle Creek (middle Pleistocene)

Lava

Pyroclastic

Basaltic andesite, undivided (Pleistocene or Pliocene)

Lava

Intrusive

Basalt of Castle Creek (middle or early Pleistocene)

Basaltic andesite northwest of Little Castle Creek (early? Pleistocene)

Basalt north of Castle Creek (early? Pleistocene)

Basaltic andesite of Castle Point (early? Pleistocene)

Basaltic andesite of Union Creek (Pleistocene or Pliocene)

Lava

Intrusive

Mount Mazama

Rhyodacite of the postcaldera dome (Holocene)

Lava

Breccia

Andesite of Wizard Island (Holocene)

Lava

Breccia

Pyroclastic

Andesite of Merriam Cone (Holocene)

Lava

Breccia

Andesite of the central platform (Holocene)

Lava

Breccia

Andesite of the east basin (Holocene)

Deposits of the climactic eruption of Mount Mazama (Holocene)

Fine-grained lithic- and crystal-rich ignimbrite

Undivided climactic unit

Lithic breccia

Ring-vent-phase ignimbrite

Wineglass Welded Tuff of Williams (1942)

Plinian and other Holocene pumice-fall deposits

Holocene preclimactic rhyodacite (Holocene)

Felsite

Vitrophyre

Pumiceous carapace

Pyroclastic

Rhyodacite of Sharp Peak (late Pleistocene)

Andesite south of Bear Bluff (late Pleistocene)

Pyroclastic

Lava

Tuff breccia

Rhyodacite of Bear Bluff (late Pleistocene)

Evolved Pleistocene preclimactic rhyodacite (late Pleistocene)

Felsite

Vitrophyre

Pumiceous carapace 

Pyroclastic

Mingled lava of Williams Crater (late Pleistocene)

Dacite of Munson Valley (late Pleistocene)

Prismatically jointed block unit

Monolithologic breccia

Andesite of Lightning Spring (late Pleistocene)

Andesite of Steel Bay (late Pleistocene)

Andesite of Pumice Point (late Pleistocene)

Andesite of Devils Backbone (late Pleistocene)

Andesite south of The Watchman (late Pleistocene)

Dacite of The Watchman (late Pleistocene)

Felsite

Pumiceous carapace and dense vitrophyre

Pyroclastic-flow deposits

Andesite of Hillman Peak (late Pleistocene)

Dacite below Llao Rock (late Pleistocene)

Andesite of Grotto Cove (late Pleistocene)

Basaltic andesite of Hillman Peak (late Pleistocene)

Lava

Intrusive

Pyroclastic

Dacite of Pumice Castle (late Pleistocene)

Lava

Pyroclastic

Basaltic andesite of Steel Bay (late Pleistocene)

Pyroclastic

Lava

Andesite west of Pumice Point (late Pleistocene)

Andesite of the west wall (late Pleistocene)

Andesite west of Red Cone (late Pleistocene)

Andesite of the boat landing (late Pleistocene)

Dacite east of Palisade Point (late Pleistocene)

Dacite of Steel Bay (late Pleistocene)

Lava

Pyroclastic

Andesite of Merriam Point (late Pleistocene)

Andesite of Llao Bay, upper unit (late Pleistocene)

Andesite east of Spruce Lake (late or middle Pleistocene)

Dacite of Palisade Point (late or middle Pleistocene)

Andesite of Llao Bay, lower unit (middle Pleistocene)

Andesite of Roundtop (middle Pleistocene)

Andesite east of Munson Valley (middle Pleistocene)

Andesite of the gaging station (middle Pleistocene)

Dacite north of Castle Creek (middle Pleistocene)

Lava

Pyroclastic

Andesite of Garfield Peak (middle Pleistocene)

Dacite south of Garfield Peak (middle Pleistocene)

Andesite of Applegate Peak (middle Pleistocene)

Lava

Intrusive

Andesite east of Wineglass (middle Pleistocene)

Andesite of Cloudcap Bay (middle Pleistocene)

Dacite of Munson Ridge (middle Pleistocene)

Andesite west of Fumarole Bay (middle Pleistocene)

Andesite below Rim Village (middle Pleistocene)

Dacite of Sentinel Rock (middle Pleistocene)

Andesite of Kerr Notch (middle Pleistocene)

Dacite of Chaski Bay (middle Pleistocene)

Andesite south of Mount Scott (middle Pleistocene)

Dacite of Mount Scott (middle Pleistocene)

Lava

Mudflow breccia

Pyroclastic

Dacite of Cavern Creek (middle? Pleistocene)

Dacite of phantom cone (middle Pleistocene)

Andesite of phantom cone (middle Pleistocene)

Lava

Intrusive

Submerged outcrops of the caldera walls, undivided (Pleistocene)

Regional Volcanism, East

Andesite of Scott Creek (late? Pleistocene)

Lava

Pyroclastic

Andesite of Crater Peak (late Pleistocene)

Lava

Pyroclastic

Basaltic andesite south of Crater Peak (late Pleistocene)

Basaltic andesite north of Crater Peak (late? Pleistocene)

Andesite south of Lookout Butte (middle Pleistocene)

Lava

Pyroclastic

Basalt west of Sun Creek (middle Pleistocene)

Basaltic andesite of Maklaks Crater (middle Pleistocene)

Lava

Pyroclastic

Basalt of Sand Ridge (middle Pleistocene)

Lava

Pyroclastic

Basaltic andesite northeast of Boundary Butte (middle Pleistocene?)

Lava

Pyroclastic

Rhyodacite of Pothole Butte (middle Pleistocene)

Felsite

Vitrophyre

Rhyodacite south of Crater Peak (middle Pleistocene)

Rhyodacite of Scott Creek (middle Pleistocene)

Andesite of Sand Creek quarry (middle? Pleistocene)

Andesite northeast of Annie Falls (middle Pleistocene)

Basaltic andesite east of Cavern Creek (middle? Pleistocene)

Andesite south of Sand Creek (middle? Pleistocene)

Lava

Pyroclastic

Basaltic andesite east of Dry Butte (middle? Pleistocene)

Basaltic andesite of Boundary Butte (middle? Pleistocene)

Andesite of Sun Creek (middle Pleistocene)

Dacite west of The Pinnacles (middle Pleistocene)

Basaltic andesite north of Lookout Butte (middle Pleistocene)

Andesite west of Sand Creek (middle Pleistocene)

Basaltic andesite east of Annie Falls (middle Pleistocene)

Rhyodacite west of Cavern Creek (middle Pleistocene)

Dacite of Sand Creek (early Pleistocene)

Andesite south of Dry Butte (early Pleistocene)

Dacite of Dry Butte (early Pleistocene)

Contact—Long dash where gradational

Internal contact—Indicates base or margin of lava flow

Dike—Narrower than approximately 5 m

Fault—Dotted where concealed; bar and ball on downthrown side

Bedform crest—Shown in units cb, cu, and cf

Moraine crest—Open circle where concealed

Slump surface—Dotted where inferred (units abt, cb, cf)

Crater Lake National Park boundary

Volcanic vent—Does not include dikes feeding lava flows

Dated sample—Location and age (ka) of sample dated by K-Ar or 40Ar/39Ar 

methods. See DESCRIPTION OF MAP UNITS for units containing 

sample localities without ages 

Geothermal exploration well

bwn bwnp bw bwp

br brp

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boe

arw

asl

boi bop

bn

ao

bow

bbc

bbf

bck

bc bcp

blcp

bsc bscp

bf bfpbfi

bu bui bup

bx bxi bxp at atg ati

bxn bxni baw

bbi bbp bcw

bwc bwci bwcp

acc accp

bln bac

bcc

bcn

buc

? ?

?

? ?

buci

asc ascp

acr acrp bcsp

alb albp

bsw bmc bmcp

bsr bsrp bt

rpb rpbv

rcs

rsc

aaf bep acs acsp bdp

aq

bap

as dw blp

asw baf

rcc

dsc adsi

dd

btp

atw

dwf dwv

dwp

ah

dlp

dc

dcp

agc

bh

bhp

bhi

ad

aww

bs

bsp

apw

abl dpe

dsb dsbp

alu

dpt

am

all ar

amv ags

awe

dcn dcnp

ag dg

aa aai

ac

dm

ams

arv

ak

dr

db

apn apni

ds dsf dsp dcc

su

af

dpn

 r rb

aw awb awp

apc apcb

amc amcb

ae

 cp

cw

 cfcb

cu

 rhp

rh rhv rhc

rs

rbb ab

abp

abt

re rev rec

 rep

mw

dvb

dv

als asb apu

al sl

t

ls

g

g

g

s

s

g

 bo

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bib

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bcnp

Northwest Southwest Mount Mazama East

SEDIMENTARY DEPOSITS VOLCANIC ROCKS

CORRELATION OF MAP UNITS

Holocene

QUATERNARY TERTIARY

Late Pleistocene Middle Pleistocene

Pleistocene Pliocene

Early

Pleistocene

Age

(ka)

10

25

50

100

128

200

250

300

350

400

600

775

[Touching boxes indicate units are part of same episode. Late/middle Pleistocene boundary from Stirling and others (1998). Middle/early 

Pleistocene boundary from Bassinot and others (1994). See DESCRIPTION OF MAP UNITS for specific age determinations]

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

SCIENTIFIC INVESTIGATIONS MAP 2832

SHEET 2 of 4

Pamphlet and CD-ROM accompany map

 

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, or call 1–888–ASK–USGS

Available on World Wide Web at http://pubs.usgs.gov/sim/2832/

Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

By

Charles R. Bacon

2008