A

K

J

I

H

F G E

D

C

B

0 1 2 3 4 KILOMETERS

122°05'W

122°05'W

42°54'N 42°54'N

122°10'W

122°10'W

42°58'N 42°58'N Roundtop Cleetwood

Cove

Llao

Rock

Llao

Bay

Palisade

Point

Skell

Head

Sentinel

Rock

Kerr

Notch

Sun

Notch

Phantom

Ship

Eagle

Point

Wizard

Island

The

Watchman

Dutton

Cliff

Dyar

Rock

Garfield

Peak

Castle

Crest

Discovery

Point

Hillman

Peak

Merriam

Point

Pumice

Point

Wineglass

Redcloud

Cliff

Pumice

Castle

Devils

Backbone

boat

landing gaging

station

Rim

Village Crater

Lake

Lodge

Applegate

Peak

Eagle Cove

Chaski Bay

Danger

Bay

Steel Bay

Cloudcap

B

ay

Grotto

Cove

Skell

Channel

Crater

Lake

1950

2025

2100

2175

2250

1950

2025

2100

2175

2250

2475

2175

2325

2400

2325

2250

2175

(224±9) (269±12)

(354±4) 258±8

351±12

(216±4)

302±10

52±4

276±8

50±3

A

The

Watchman

Discovery

Point

Garfield

Peak Crater

Lake

Lodge

Rim

Village

Eagle Cove

aa

aa db g

apn?

dv

cu

ls

aa

af af

aww

als cu

cu

cu cu

 cu

cp cu als atw

dwf

dwf

cu

cb

bhp

dsbp

dwp

atw

arv dcn

dcn db als dcn

dwp

dwv

aww

ah

1950

2025

2100

2175

2250

2325

1950

2025

2100

2175

2250

2400 2400

2475

2400

2325

(52±4)

(50±3)

61±8

73±6

62±7

70±4

150±9

B

The

Watchman

Hillman

Peak

Skell Channel

Devils

Backbone cu als atw dwf

dwf

cu ah

cu

cu

ah

aww bhi

bh

bhp

dsbp am

all

aww

aww

af

dwp

dwv

ah

cb

cb atw

cu cp

dvb

cb

ad

atw

cu cu cp

1950

2025

2100

2175

2250

2325

2400

2475

1950

2025

2100

2175

2250

61±8

73±6

62±7

150±9

70±4 (131±18)

C

Devils

Backbone

Hillman

Peak

Merriam

Point

aww

ah

ah

ah

cb

dvb

cb cu cu cp bh dcp cu dlp dc

cu

dlp

ad atw

cu cu

bhi

bh

dsbp

am

af

aww

am

am

alu

alu

all

aww

rh

asb

cf

cp cb

rhp

all

bhp

2400

2325

1950

2025

2100

2175

2250

1950

2025

2100

2175

2250

2325

2400

62±7

131±18

172±11

116±9

43±6

109±19

137±17 (unit all)

153±12 (unit all)

Merriam

Point Llao Bay

Llao Rock

Note that western of two unit rh

D dikes is obscured by promontory

ad atw

cp

dcp

bh

dsb

dsb

s

s

rhp

dcp

dc dlp

rhp

asb

asb

aww

am

aww

alu alu

all

alu

all rh

all

dc

dc

aww

cu

cucp cp cw cf rhp rhp

dlp dlp

rh

cp

cp

cp

s

cu

1950

2025

2100

2175

2250

2325

2400

2400

2325

2250

2175

2100

2025

1950

137±17 (unit all)

(42±6)

43±6

109±19

E Steel Bay

Llao Rock

rh

alu

s

cp

cp

cp rhp

s

bs

bsp re

rhp dlp dc

aww

asb

dsb

dsb

dcp

apw

dc

dcp apu

asb

all

alu alu

all

apw

2100

2025

1950 1950

2025

(42±6)

72±7

(47±20)

116±5

117±3 122±20

cp

rhp

asb

all

alu

alu apw

apw

s

alu

apu dcp dlp dc dcp

dsb

cp

cp

rhp

cp asb

apu

re

F

Steel Bay

Pumice

Point

1950

2025

1950

2025

2100

(116±5)

47±20

122±20

(117±3)

189±3

102±10 119±9

dcp apu

rhp

alu

dsb

g

agc

ags

cb

cb

g

dlp? rhp

rhp rhp

dlp

cp

cp

cu

cp

g

dpe

dpt

agc

dcp abl

abl

dpt

all

abl

agc

cu cp

g

cw cw cu cu

rh

cw cw cp

cu

cu cp

g

G Palisade

Point

Cleetwood Cove

Pumice

Point

gaging

station

boat

landing

1950

2025

2100

2175

2250

1950

2025

2100

2175

2250

(74±10) (68±13) (159±13)

111±9

cb cb

cp

ar cp

cw

cw

cw

g cp

dpe

g

g

agc

aa

aa awe

agc

aa

ac dr

ak

cb cw

cp

rhp

cu

g

H

Grotto Cove Skell Head

Wineglass

Roundtop

Palisades

1950

2025

2100

2175

2250

2325

1950

2025

2100

2175

2250

2325 2400

341±8 340±6

71±6

(306±5)

336±6

288±13

231±6

dr

dr

dr

ak

dc

dcp

re dc

dc

dcp aa aa ac

ac

ac

ak

s

ac

g

aa

cu

cu

cu

cu

cb

cb

cb

cb

cb cu cw

cp

cw

cp

cp

cp cp

cp

ac

aa

I

Redcloud Cliff

Skell Head Cloudcap Bay

Sentinel

Rock

Pumice

Castle

1950

2025

2100

2175

2250

1950

2025

2100

2175

2250

2325

2400

2475

2100

2175

2250

2325

2400

2100

2175

2250

306±5

231±10

245±10

346±20 403±12

(244±4)

dr

s ak

cp g

cb

cb

cu

db

ak

aa

apn

apn

apni

dpn

dpn

cp

aa

apn

J

Sentinel

Rock

Kerr Notch

Danger Bay

Sun

Notch

Dutton

Cliff

2100

2175

2250

2325

1950

2025

2100

2175

2250

2325

2400

2475

2400

2475

2250

2325

2400

2250

2325

2475 2400

(307±12)

(211±16)

224±9 (269±12)

(354±4)

(403±12)

apn

aa

dpn

apni

cp ak

ak

aa

aa

db

db

aa?

ak?

ak

aa

cb

ag

ag?

aai

db

db

cb

s

aa

K

Castle

Crest

Eagle

Point

Garfield

Peak

Dyar

Rock

Chaski Bay

Applegate

Peak

Sun Notch

Phantom

Ship

Danger Bay

Kerr

Notch

Dutton

Cliff

244±4

EXPLANATION

[Unit labels and colors correspond with those on geologic map (sheet 1)]

The geology of the caldera walls was mapped on photographs taken from Crater Lake, Wizard Island, and helicopter. This information was transferred 

to panoramic views made from photomosaics. Topographic contours (15-m contour interval) for each photograph were computed from a DEM. 

Computer-generated contour overlays for photos were superimposed on photomosaics and re-drafted by hand. Elevations in the DEM were accurate to 

approximately 5 m for points on a grid with 30-m spacing. As a result of the relatively large horizontal distance between data points, contours 

generalize the morphology of the caldera wall surface. They are primarily intended as a guide to thicknesses of map units in panoramic views of 

varying scale.

Covered areas—Shows where rock units are covered by talus or vegetation

Contact—Short dashes where concealed

Internal contact—Indicates base or margin of lava flow or pyroclastic deposit within unit

Fault—Short dashes where concealed (Panoramas A and K only)

Visual boundary—Shows horizon and visual boundary clarifying three-dimensional surface

Lake surface—At time photos were taken in 1979

Camera site—Approximate location where photographs were taken

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

parentheses denote hidden sample localities that have been projected to panorama surfaces. 

Samples plotted below Panoramas D and E represent approximate locations of subsurface 

samples collected from the caldera wall by manned submersible

Computer-generated contour—Accurate to approximately 5 m

Building

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

SCIENTIFIC INVESTIGATIONS MAP 2832

SHEET 4 of 4

Pamphlet and CD-ROM accompany map

Geologic Panoramas of Crater Lake Caldera Walls

Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

By

Charles R. Bacon

2008

2325

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/

The great cliff at Llao Rock (Panorama D), which dominates this aerial 

view looking northwest, slices into Holocene rhyodacite lava (unit rh) 

that filled and overflowed the explosion crater formed in the early stages 

of the same eruption. Ash from the explosive phase of this eruption (unit 

rhp), which occurred 100–200 years before the caldera-forming climactic event, is found as far away as northern Nevada and northeastern 

California. Climactic pumice fall (unit cp) rests on the craggy top of the 

lava flow but was stripped from its lower flanks by pyroclastic flows of 

the ring-vent phase of the climactic eruption. Several lava and pyroclastic units exposed in the caldera wall below Llao Rock range in age from 

unit all (~140–170 ka) to unit asb (43±6 ka here). The broad shield 

volcano (lowest third of wall), composed of units all and alu, and the 

thick wedge of unit am (left) are clearly visible.

Aerial view to west-southwest of Llao Rock from Steel Bay (Panorama 

E). Note the thick, light-colored wedge of bedded, near-vent pumice-fall 

deposit (unit rhp) under the right extent of the Llao Rock lava flow (unit 

rh). Pumice-fall deposit decreases in thickness to east and also is present 

lining the explosion crater under the Llao Rock lava flow, where it has 

been compacted and fused to form dark, dense vitric tuff for several 

meters thickness against the overlying lava. Two dikes can be traced 

upward into dacite of Steel Bay lava (unit dsb; 116±5 ka); the more 

obvious dike stands out from the caldera wall, casting a shadow in the 

lower right corner of the photo.

Aerial view of Cleetwood Cove, looking northwest from above Palisade Point (Panorama G). 

Boat landing and lake gauge (gaging station) at left; Palisade Point at right. Holocene rhyodacite of the Cleetwood flow (Williams, 1942; unit rh) forms cliff at caldera rim above the arcuate 

cove; tongue of lava descending to lake edge is rhyodacite of the Cleetwood flow, remobilized 

from the pasty interior of the lava flow after the caldera collapsed. This and other evidence 

indicates that the Cleetwood flow was emplaced shortly before the climactic eruption, probably 

at most a few years earlier. Scalloped form of Cleetwood Cove is typical of topographic walls 

of collapse calderas that enlarge beyond the bounds of a subsiding central block by landsliding 

during and immediately following a caldera-forming eruption. In the caldera wall beneath the 

Cleetwood flow are near-vent, pumice-fall deposits from the onset of the Cleetwood eruption 

lying on pumice from the Llao Rock vent (collectively unit rhp here), underlain by andesite of 

Grotto Cove (unit agc; 71±5 ka) and andesite of the boat landing (unit abl; 102±10 ka). Trail 

to the boat landing traverses partly welded Wineglass Welded Tuff (unit cw), then descends 

forested scree slope on thick climactic pumice fall with interbedded nonwelded pyroclastic 

flows (unit cp), approximately 1-m thickness each of Cleetwood and Llao Rock pumice falls, 

and glacial till before dropping through and along base of the unit abl lava flow. Units visible 

in middle distance beyond caldera rim are forested northeast portion of the Grouse Hill rhyodacite flow (unit re; ~27 ka), Pumice Desert (unit cf), and Timber Crater shield volcano (unit atc; 

137±10 ka). Mounts Bailey and Thielsen are to left and right, respectively, of Diamond Lake in 

the distance.

Aerial view of northeast caldera wall (Panorama H). The Palisades, the tall 

cliff above talus in center, is the ice-bounded lava flow, andesite of Roundtop 

(unit ar; 159±13 ka), that rests on thick glacial till and fluvial deposits largely 

obscured by talus. Below the lake surface, these permeable deposits rest on 

glaciated andesite of Cloudcap Bay (unit ac); seepage through these deposits 

apparently prevented Crater Lake from filling significantly higher than present 

elevation (Bacon and others, 2002). To the right of the Palisades is the scree 

chute known as the Wineglass. The bowl of the glass is scree from the three 

Holocene pumice-fall deposits (units rhp and cp) and the overlying Wineglass 

Welded Tuff and proximal ignimbrite (units cw and cb, respectively); the stem 

of the glass crosses subglacial and subaerial andesite of Applegate Peak (unit 

aa; ca. 210–270 ka) lying on glacial till obscured by talus. The cliff at the 

caldera rim to the right of the Wineglass is ice-bounded andesite of Grotto 

Cove (unit agc; 74±10 ka here). On the left end of the panorama, the Palisade 

flow (Williams, 1942) forms a cliff that reaches the lakeshore (unit dpe; 111±9 

ka), fills a glacial paleovalley to the left of Roundtop, and is overlain by glacial 

till, the Holocene pumice-fall deposits, Wineglass Welded Tuff that thickens to 

the right toward the topographic low point on the rim, and proximal ignimbrite. Walker Rim, approximately the northeastern distal limit of climactic 

ignimbrite, is visible in the distance 46 km beyond the Wineglass.

Redcloud Cliff dominates this view of the east wall of the caldera 

(Panorama I). The Redcloud Cliff flow of rhyodacite lava fills the 

V-shaped vent crater from which it issued. This flow and its kin (unit 

re; ~27 ka), the Grouse Hill flow and dome and a small dome above 

Steel Bay (Panorama E), were emplaced when thick glacial ice was 

present on Mount Mazama. Also prominent are the cliff-forming 

lava (unit dc; 71±5 ka, weighted mean) and pumice-fall deposit 

(unit dcp) of dacite of Pumice Castle beneath the Redcloud Cliff 

flow. Below these are comparatively thin andesite of Applegate 

Peak (unit aa; ca. 210–270 ka), the lava shield of andesite of Cloudcap Bay (unit ac; est. 287±10 ka, weighted mean), pyroclastic flows 

and lava of dacite of Sentinel Rock (unit dr; 336±6 ka here), and 

andesite of Kerr Notch (unit ak; ~340 ka here). Dikes of units dr (at 

right end of Panorama I), ac, aa, and dc cut units older than their 

respective extrusive equivalents. Climactic pumice fall (unit cp) and 

proximal ignimbrite (unit cb) are found at the caldera rim, but Wineglass Welded Tuff (unit cw) is absent except for a small outcrop at a 

low point to the right of photo.

View looking northeast of Pumice Castle, the orange outcrop in the 

center of the photo, from overlook on Rim Drive (Panorama I). Lightcolored, bedded pumice at right is the same unit that forms Pumice 

Castle, Plinian fall deposit (unit dcp). Darker layers are incipiently to 

densely welded, more intensely to the left closer to vent. Cliff above 

pumice is lava unit of dacite of Pumice Castle (unit dc; 71±5 ka, 

weighted mean), which compressed and fused underlying pumice, and is 

overlain by climactic pumice fall (unit cp), proximal ignimbrite (unit 

cb), and a wind-reworked, pumice-rich deposit (restricted to caldera 

rim; included in unit cu). Skyline cliff at left is the Redcloud Cliff flow 

(unit re).

View northeast of Sentinel Rock from offshore from Kerr Notch 

(Panorama J). Two thick flows of dacite of Sentinel Rock (unit dr; 

306±5 ka here) fill a glacial valley carved in thinner flows of andesite of 

Kerr Notch (unit ak; 340±6 ka near here, Panorama I). Outcrop at lake 

level, left center, is andesite of phantom cone (unit apn; 346±20 and 

403±12 ka near here).

View southwest of nearly 600 m of relief 

and approximately 200,000 years of history 

in caldera wall between Kerr Notch (left) 

and Dutton Cliff (right; Panorama J). At 

right, light and dark bands dipping to left 

are flow-top and pyroclastic breccias and 

dense lava flow interiors, respectively, of 

phantom cone (Williams, 1942; unit apn; 

346±20 and 403±12 ka). Hydrothermal 

alteration and oxidization of pyrite results in 

yellowish-tan breccias. The highest band is 

dacite of phantom cone (unit dpn). Overlying units are dacite of Chaski Bay (db) and 

andesite of Kerr Notch (ak), both hydrothermally altered to some degree at this 

location, and andesite of Applegate Peak 

(aa).

Aerial view of Phantom Ship island and unnamed point in phantom cone 

(Williams, 1942). All visible rock is lava and breccia of the andesite of 

phantom cone (unit apn; 403±12 ka here). Phantom Ship tops a buttress 

on the submerged caldera wall, whose southwest side appears to be 

bounded by a northwest-trending dike (Bacon and others, 2002). The 

beach at the point becomes much more extensive at times of low lake 

level and indicates that the surface elevation of Crater Lake has varied 

within only a few meters for a considerable time (Bacon and others, 

2002).

View southwest of Garfield Peak and Eagle Crags above Chaski Bay 

(Panorama K). Cliffs at caldera rim are andesite of Applegate Peak (unit 

aa; ca. 210–270 ka), overlain by two thin flows of andesite of Garfield 

Peak at top center (unit ag; 224±9 ka). Talus rests on flat top of massive 

slide block that consists of altered lavas of units aa, ak(?), and db(?). 

Informally known as Chaski slide, the block was displaced downward 

from high on the caldera wall; an extensive debris-avalanche deposit lies 

on the caldera floor below Chaski Bay (Bacon and others, 2002). 

Several normal faults parallel to the caldera wall cut altered lavas below 

Garfield Peak, to the right of Chaski slide above Eagle Point. 

Yellowish-tan color results from oxidation of pyrite that is most evident 

in relatively permeable, flow-top breccias.

Aerial view of Crater Lake caldera looking west-northwest from area 

above Scott Creek. Mount Scott (8,928 ft elev) in right foreground, 

composed entirely of dacite lava and pyroclastic rubble (unit ds; ~420 

ka), has a mantle of climactic pumice (unit cp); long buff-colored scar 

descending to left apparently was formed by snow avalanche(s). 

Pyroclastic flows of ring-vent phase of climactic eruption left proximal 

lithic-rich ignimbrite (unit cb) in saddle on summit ridge of Mount 

Scott. From left to right, high points on caldera rim (8,013–8,151 ft elev) 

are Dutton Cliff (above Kerr Notch), Applegate and Garfield Peaks, The 

Watchman (behind Wizard Island), Hillman Peak, and Llao Rock.

View to west from Garfield Peak trail 

at approximately 7,700 ft elevation, 

showing caldera-facing normal fault 

scarp interpreted as headwall of 

incipient landslide that formed in 

response to caldera collapse. This is 

the southernmost fault recognized in a 

set of similar faults below Garfield 

and Applegate Peaks.

Aerial view toward southwest of The Watchman (left) and Hillman Peak 

(right) from near Devils Backbone (Panorama B). Light-colored exposure at bottom right is pyroclastic-flow deposit (unit dsbp) correlated 

with dacite of Steel Bay (unit dsb; 116±5 ka). Thick package of many 

lava flows is andesite of the west wall (unit aww; 70±4 ka). Gray scree 

slopes above unit aww lavas are near-vent fall deposit of hornblende 

basaltic andesite of Hillman Peak (unit bhp) on either side of crags 

composed of lithified breccia (bhp) and intrusive rock (unit bhi; 73±6 

ka). Andesite of Hillman Peak (unit ah; 61±8 ka) forms the summit of 

its namesake. The Watchman is a glaciated horn sculpted from a thick 

dacite lava flow (unit dwf; 50±3 ka) whose feeder dike forms sail-like 

outcrops on the caldera wall. Slope above unit aww lava at caldera rim 

on extreme right is supported by dacite of Munson Valley pyroclastic 

flow (unit dvb; ~35 ka).

View northwest shows the two segments of the Devils Backbone dike that cut all four visible lava units (Panorama C): 

lower andesite below Llao Rock (unit all; 150±9 ka here), 

andesite of Merriam Point (unit am; 131±18 ka), andesite of 

the west wall (unit aww; 70±4 ka), and andesite south of 

The Watchman (unit atw, the lava cliff on the caldera rim to 

the right of upper dike segment; 62±7 ka here). Lava flows 

correlated with the Devils Backbone dike (unit ad; ca. 

40–50 ka) extend as far as 11 km west of the caldera rim. 

Highest slope to the left of left dike segment is underlain by 

dacite of Munson Valley pyroclastic flow (unit dvb; ~35 ka).