2,722 m

2,550

2,350

2,150

1,950

1,750

1,550

1,350

1,152 m

Elevation

meters above

sea level

Annie Creek

Annie Falls

Crater

Peak

Pumice

Flat

Bear

Bluff

Union

Peak

Sun Creek

Grayback Ridge

Maklaks Pass

Sand Creek

The Pinnacles

Maklaks

Crater

Sand Ridge

Cavern Creek

Kerr Notch

Sun Notch

Munson Valley

Garfield

Peak Applegate

Peak

ANNIE SPRING FAULT

Arant

Point

Whitehorse

Bluff

Castle

Point

Castle Creek

Little Castle Creek

Thousand

Springs

Mount

Scott

central

platform

Wizard

Island

Chaski

Bay

Phantom

Ship

Williams

Crater

Hillman

Peak

Merriam

Cone

Llao

Rock

Grouse

Hill

Roundtop

Wineglass

Scott Bluffs

Anderson Bluffs

Sharp

Red Peak

Cone

Red

Cone

Spring

RED CONE SPRING FAULT

Timber

Crater

Pumice

Desert

Crater Creek

Sphagnum

Bog

Crater

Springs

Union Creek

Copeland

Creek

Bybee Creek

Crescent

Ridge Bald

Crater

Mazama

Creek

Boundary

Springs Desert Ridge

Klamath

Ridge

Desert

Cone

Gaywas

Peak

Desert Creek

Mazama

Rock

Tiny Creek

Cloudcap

Grotto

Cove

Cloudcap

Bay

Danger Bay

Sentinel

Rock

Skell

Head

Eagle

Point

Eagle

Cove

The

Watchman

Discovery

Point

Wheeler Creek

Anderson

Spring

Pothole

Spring

Cascade

Spring

Crater

Lake

Pothole Creek

Bear Creek

Bear

Butte

Pumice

Point

Palisade

Point

Steel Bay

Merriam

Point

Llao

Bay

62

138

209

62

A

B

C

Cleetwood

Cove

D

B

B1

B3 B2

B4

B5

D D1

D2

D

C1

C2

C3

C4

C

A1

A2

A4

A5

A

A3

0 500 1,000 Feet

0 100 200 300 400Meters

N

0 500 1,000 1,500 Feet

0 250 500 Meters

N

0 750 Feet

0 100 200 300 Meters

N

0 500 1,000 Feet

0 100 200 300 400 Meters

N

INTRODUCTION

Crater Lake partially fills the caldera that formed approximately 7,700 years ago during the eruption of a 12,000-ft-high volcano 

known as Mount Mazama. The caldera-forming, or climactic, eruption of Mount Mazama devastated the surrounding landscape, 

left a thick deposit of pumice and ash in adjacent valleys, and spread a blanket of volcanic ash as far away as southern Canada. 

Prior to the climactic event, Mount Mazama had a 400,000-year history of volcanic activity similar to other large Cascade volcanoes such as Mounts Shasta, Hood, and Rainier. Since the caldera formed, many smaller, less violent eruptions occurred at volcanic vents below Crater Lake’s surface, including Wizard Island. A survey of Crater Lake National Park with airborne LiDAR 

(Light Detection And Ranging) resulted in a digital elevation map of the ground surface beneath the forest canopy. The average 

resolution is 1.6 laser returns per square meter yielding vertical and horizontal accuracies of ±5 cm. The map of the floor beneath 

the surface of the 1,947-ft-deep (593-m-deep) Crater Lake was developed from a multibeam sonar bathymetric survey and was 

added to the map to provide a continuous view of the landscape from the highest peak on Mount Scott to the deepest part of Crater 

Lake. Four enlarged shaded-relief views provide a sampling of features that illustrate the resolution of the LiDAR survey and 

illustrate its utility in revealing volcanic landforms and subtle features of the climactic eruption deposits. LiDAR’s high precision 

and ability to “see” through the forest canopy reveal features that may not be easily recognized—even when walked over—

because their full extent is hidden by vegetation, such as the 1-m-tall arcuate scarp (B4) near Castle Creek.

MAP LOCATION

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://pubs.usgs.gov/sim/3223/

Suggested citation: Robinson, J.E., Bacon, C.R., and Wayne, Chris, 2012, Under 

trees and water at Crater Lake National Park, Oregon: U.S. Geological Survey 

Printed on recycled paper Scientific Investigations Map 3223 (http://pubs.usgs.gov/sim/3223/).

Under Trees and Water at Crater Lake National Park, Oregon

By

Joel E. Robinson,1 Charles R. Bacon,1 and Chris Wayne2

2012

OREGON

A. Wizard Island (A1) rises from the floor of the lake to 760 ft 

(233 m) above Crater Lake’s surface. The island is made of 

andesitic lava and scoria (dark, frothy ejected lava) erupted 

approximately 7,000 years ago as the lake was filling to 

almost its present level. Lava flows with marginal levees (A2) 

surround the cinder cone and can be followed from the 

high-resolution LiDAR data into the lower-resolution bathymetry beneath the lake's surface. Farther offshore are 

drowned lava deltas (A3) that formed as lava flowed into the 

lake when the lake level was lower. A series of these older, 

drowned shorelines help us understand the lake filling 

history. The white band (A4) surrounding Wizard Island lacks 

precise elevation data in shallow water where bathymetric 

data were not collected. The Wizard Island boat dock can be 

seen on the island’s southern shore to the east of a large 

leveed lava flow. The Wizard Island foot trail (A5) winds its 

way through the forest going up the south side of the cinder 

cone.

B. Two creeks, Little Castle and Castle, flow through gorges 

cut into Mount Mazama’s climactic pyroclastic-flow deposit. 

The deposit formed from a mixture of hot gas, pumice, and ash 

that moved rapidly down the slopes of Mount Mazama and 

into adjacent valleys. At the confluence of the creeks (B1), the 

climactic pyroclastic-flow deposit is about 330 ft (100 m) thick. 

Through the forest cover, LiDAR reveals features on the 

surface of this deposit. Many thinner flow deposits have 

finger-shaped flow lobes (B2). One prominent pyroclasticflow deposit extends past Castle Point and banks in against it 

and a low ridge of glacial deposits. At the toe of this flow are 

a series of finger-shaped flow lobes. An extensional rift (B3) 

at the nose of Castle Point scars the surface of this deposit. 

After deposition, the deposit began to compact because of 

cooling and settling. The rift opened as the deposit tilted away 

from the point toward the deposit’s thickest part at the valley 

center, where compaction was the greatest. A 1-m-tall 

arcuate scarp (B4) faces west, where the margin of a pyroclastic flow deposit became unstable, collapsed, and fed a 

thin secondary pyroclastic flow to the northwest. South of 

Castle Point are crater vents for young basaltic flows, one 

round and one pear shaped (B5). The basalt erupted after the 

glaciers retreated, but before the Mazama climactic eruption, 

between about 13,000 and 7,700 years ago.

C. On the northeast edge of Crater Lake, the scallop-shaped 

Cleetwood Cove formed during the climactic eruption of 

Mount Mazama as the mountain foundered into the opening 

caldera. Northeast of the cove is the Cleetwood rhyodacite 

lava flow (C1), which erupted as little as a few months before 

the climactic eruption. When the caldera collapsed, the lava 

flow still had a molten interior that oozed into the caldera, 

forming a rugged tongue between the high cliffs on either side 

of Cleetwood Cove. The drainage of lava from the main flow 

down the caldera wall (C2) and to the northeast—beyond this 

view—caused the cooler, more ridged lava-flow surface to 

sag and crack apart (C3). This opened up large rifts that can 

be seen adjacent to the Cleetwood Trail parking lot and Rim 

Drive. The trail to the tour boat landing (C4) is visible zigzagging its way down the caldera wall. The white band separating bathymetry survey from LiDAR survey lacks precise elevation data in shallow water where bathymetric data were not 

collected. Parallel east-west apparent grooves on lake floor 

and north-south stitching are artifacts of bathymetric data 

processing.

D. Sharp Peak (D1) is the largest of 12 rhyodacite lava domes 

that erupted about 18,000 years ago to the northeast of the 

caldera. The linear trend of the domes suggests they erupted 

along a radial fracture created by Mount Mazama. Just to the 

north of Sharp Peak is a long northeast-trending rift (D2) 

found in the climactic pyroclastic-flow deposit. The rift 

opened as the deposit compacted and tilted to the north 

toward the valley center, where the deposit is thickest. The 

tilting of the deposit’s surface pulled it away from the highland south-southwest of Sharp Peak. In the southwest 

quarter of the image, running water rapidly carved parallel 

northeast-trending gullies into the loose surface of the 

climactic pyroclastic-flow deposit. The LiDAR reveals many 

features like this within Crater Lake National Park.

DATA SOURCES

Robinson, J.E., 2012, Digital topographic map of Crater Lake National Park and vicinity, Oregon, based on LiDAR survey of 

August–September 2010, and bathymetric survey of July 2000: U.S. Geological Survey Data Series DS 716, (Available at 

http://pubs.usgs.gov/ds/716.)

Gardner, J.V., and Dartnell, Peter, 2001, 2000 multibeam sonar survey of Crater Lake, Oregon; Data, GIS, images, and movies: 

U.S. Geological Survey Digital Data Series DDS–72, (Available at http://geopubs.wr.usgs.gov/dds/dds-72.)

ADDITIONAL READING

Bacon, C.R., 2008, Geologic map of Mount Mazama and Crater Lake caldera, Oregon: U.S. Geological Survey Scientific Investigations Map 2832, 4 sheets, scale 1:24,000, 45 p. pamphlet (Available at http://pubs.usgs.gov/sim/2832/.)

Bacon, C.R., and Lanphere, M.A., 2006, Eruptive history and geochronology of Mount Mazama and the Crater Lake region, 

Oregon: Geological Society of America Bulletin, v. 118, p. 1331–1359.

Bacon, C.R., Gardner, J.V., Mayer, L.A., Buktenica, M.W., Dartnell, Peter, Ramsey, D.W., and Robinson, J.E., 2002, Morphology, 

volcanism, and mass wasting in Crater Lake, Oregon: Geological Society of America Bulletin, v. 114, p. 675–692.

1 0 1 2 3 4 KILOMETERS

1 0 1 2 3 4 MILES

1

U.S. Geological Survey, Menlo Park, California

2

National Park Service, Crater Lake, Oregon

1937 U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3223