Rose Place

Nice

Wild Bill

Place

Pole Garden

Bartlett

Springs

Newman

Springs

Riviera

Estates

Riviera West

Mount Hannah

Lodge

Clear Lake

Riviera

Sunrise Vista

Clearlake

Park

Clearlake

Highlands

Clearlake

Oaks

Clear

Lake Keys

Glenhaven

Cooper

Tatu

Dos Rios

Indian

Springs

Parramore

Springs

Enterprise

Vann

Three

Crossing

Hearst

Fouts Springs

Stonyford

Highland

Springs

Hough Springs

Marks Place

Glenview

Soda Bay

Kelseyville

Finley

Rice Fork

Summer Homes

Lower Lake

Twin Lakes

Buckingham

Park

Lucerne

Pepperwood

Grove

Jenks Place

Keller 

Place

O'Neil Place

Hays Place

Carpenter

Place

Pomo

Potter Valley

Laughlin

Redwood

Valley

Bonnie View

Crocker Place

Four Pines

Upper Lake

Saratoga

Springs

Wilbur

Springs

Farley

Elk Valley

Deep Hole

Valley

Rodeo Valley

Deer Valley

Mill Valley

Summit Valley

Lower Letts

Valley

High Valley

Star Valley

Corral Valley

Roun d Valley

Shaul Valley

The Basin

Little Squaw

Valley

Gravelly

Valley

Sawtelle

Valley

Excelsior

Valley

Paradise

Valley

Logan Basin

Eden Valley

Rocky Basin

Pine Lake

Basin

Bennett

Valley

Salt

Spring

Valley

Jack Hollow

Hayshed Basin

Windy Point

Sky Rock

Little

Pinnacle

Bartlett

Mountain

Round

Mountain

Red Rock

Pinnacle Rock

Elk Knob

Pine Mountain

Ruppert Point

Reister Rock

Chocolate

Peak

Chalk

Mountain

Red Rocks

Stony Top

Brushy

Mountain

Bald Mountain

Counterfeit

Hill

Bald Mountain

Roundtop

Mountain

Evans Peak

Reister Knoll

Round

Mountain

Signal Peak

Snow Mountain

Snow Mountain

East

Crockett Peak

Snow Mountain

West

Copper Butte

Bloody Rock

Little

Chemise Knob

Big Chemise

Knob

Little Round

Mountain

Bear Peak

Prather Mill

Red Mountain

Horse

Mountain

Elk Mountain

Poges Peak

Big Rock

Felkner Hill

Pine Kop

Kern Point

Foster

Mountain

High Rock

Goat Mountain

Potato Hill

Hornet

Nest Hill

Gilmore Peak

Monument Peak

Gilliam Rock

Red Rock

Split Rock

Pacific Point

Monkey Rock

Little

Bear Rock

Cherry Hill

Calamese Rock

Panther Rock

Pole Point

Red Rock

Windy Point

Swallow Rock

Goat Rock

Bald Mountain

Hull Mountain

Bald Mountain

Negro Head

Round

Mountain

South Peak

Wright Peak

Howard Peak

Buckingham

Peak

Clark Peak

Mount Hannah

Mount

Olive

Sugarloaf

High Rock

Little Round

Mountain

Kneecap

High Point

Round

Mountain

Brewery Hill

Scotts

Mountain

Lakeport Peak

Orr Peak

Coyote 

Rocks

Bear Mountain

Cooks

Mountain

Sugarloaf

Baldy

Mountain

Bally Peak

Quackenbush

Mountain

Brushy

Sky High

Sky High

Schoolteacher

Hill

Pine Mountain

Dali-Dona

Black Butte

Ford Hill

Brushy

Mountain

Coyote Rock

Haydon Rock

Little Baldy

Buzzard Roost

Umbrella

Butte

Blue Rocks

Dicks Butte

Little Horse

Mountain

Potato Hill

Kibbey Peak

Garrett

Mountain

Saint John

Mountain

Dry Creek

Hill

Sheetiron

Mountain

Triplet Butte

Big Signal

Peak

Impassable

Rock

Little

Signal Peak

The Island

Elephant Hill

Sugarloaf

Hill

Poison Rock

Chimney Rock

Skunk Rock

Table Rock

Rose Rock

Haynes Hill

Red Rock

Thatcher

Butte

McCabe Point

Poe Mountain

Hunter Point

Hells Peak

White Rock

Mountain

Sleeper Peak

Hog Point

Griner Peak

Twin Knobs

Youngs Peak

Bloody Island

Charlie Alley

Peak

High Peak

Rocky Point

Little Signal

Pine Mountain

Gibson Hill

Coyote Peak

Cold Spring

Mountain

Fox Peak

Bald Mountain

Round

Mountain

Grizzly Peak

Twin Sisters

Baldy

Buck Mountain Mountain

Gold Point

Yellowjacket

Rattlesnake Spring

Spring

Martini

Spring

Iron Spring

Mud Spring

Conner

Cabin

Spring

Redwine

Spring

Jarbow Spring

Chief Spring

McCoy Spring

Cold Spring

Cold Spring

Jerusalem

Spring

Big Spring

Appletree

High Glade

Spring

Sulphur

Spring

Hazel Spring

Addington

Springs

Jesse Spring

Royal Spring

Allen Springs

Gas Spring

Able Spring

Ellen Spring

Cross Spring

Box Spring

Buckhorn

Spring

Rackout

Spring

Twin Springs

Pebble Spring

Parramore

Springs

Violet Spring

Hayward

Spring

Noel Spring

Soda Spring

Board

Camp

Spring

Candy

Bucket

Spring

Freezeout

Spring

Trough Spring

Red Eye

Spring

Cold Spring

Champagne

Spring

Hornet Nest

Spring

Cooks Springs

Bear Wallow

Spring

Complexion

Spring

Dead Shot

Spring

Ford Spring

Chipmunk

Spring

Spring

Poison

Smith

Spring

Carlsbad

Spring

Sulphur

Spring

Dead Cow

Spring

Logan Spring

Barrel Spring

Big Soda

Spring

Grouse Spring

Crabtree

Hot Springs

Summit Spring

Rabbit

Glade

Spring

Fir Root

Spring

Madrone

Spring

Big Spring

Youngs

Corral

Spring

Knobcone

Spring

Pine

Mountain

Spring

Twin Springs

Sheetiron

Spring

Box Spring

Watson Spring

Vulture

Spring

Sulphur

Spring

Salt Spring

Madrone

Spring

Plank

Cabin

Spring

Witter

Springs

Grizzly

Spring

Hog Spring

Eaton Springs

Cherry Spring

Til Jones

Spring

Cold Spring

Deadshot

Spring

Blank Spring

Bear Spring

Dunfield

Spring

Timbered Ridge

Bentley

Ridge

Hosea Ridg e Hog Hole Ridge

Thatcher Ridge

E t s e l R i d g e

Sallady

Ridge

Doan Ridge

Kilgore Ridge

Billy

Pike Ridge

Dingman Ridge

Clifton Ridge

P i n t o R i d g e

P l a s k e t t

R i d g e

B a r b

R i d g e

Hunter Ridge

Rocky Basin Ridge

O’Neil Ridge

M c C o y R i d g e

Camp Meeting Ridge

H o r s e P a s t u r e R i d g e

Old Man Ridge

Jarbow

Ridge

J a m i s o n R i d g e

Pedro Ridge

Shim

min Ridge

W i l l i s R i d g e

B r i g h t

R i d g e

L o n g D o e R i d g e

Charcoal Ridge

Buckhorn Ridge

Skidmore Ridge French Ridge

S p a n i s h R i d g e

Markham Ridge

Buck Rid g e

Cedar Ridge

Kern Ridge

K n e e c a p

R i d g e

Five Spring Ridge

Sheep Ridge

Middle Rid g e

Gibson Ridge

Panther Ridge

Red

Rock Ridge

H o r s e R i d g e

B o a r d m a n R i d g e

E r i c s o n R i d g e Sanhedrin Mountain

Box Spring Ridge

English Ridge

North Ridge

South Ridge

Log

Ridge

McLeod

Ridge

Bevans Ridge

A n d e r s o n R i d g e

B r u s h y C a m p R i d g e

Deaf y Ri d g e

Peavine Rid g e

Happy Camp Ridge

Lost Camp

Ridge

Felkner Ridge

Brushy Ridge

Black Diamond Ridge

A u k Au k Ri d g e

Open Ridge

North Ridge

Blue Slides Ridge

L o n g R i d g e Board Camp Ridge

M i n e r Rid g e

Big

Ridge

Sumner Ridge

French R i d g e

Alder Spring

Ridge

Sled

Rid g e

P i t n e y

R i d g e

McCabe Ridge

Dave Phelps Ridge

John Alley Ridge

Pitney

Ridge

Sam Alle y

Ridge

 M i d d l e M o u n t a i n

M i d d l e M o u n t a i n

Streeter Ridge

Tr o u g h

S p r i n g

R i d g e

Hale Ridge

S u l l i v a n R i d g e

L ittle Sullivan Ridge

Pine Ridge

Letts Ridg e

Crackerbox Ridge

Hornet Nest Ridge

Smelt Road Ridge

Gilmore Ridge

Lovelady

Ri d g e

P a c i f i c R i d g e

Soapstone Ridge

Spanish Ridge

Indian Ri d g e

Red Ridge

Mary Ann Ridge

Windy Ridge

Ladder Ridge

Wild

Bill Rid g e

Hough Ridge

Rocky

Ridge

R u p p e r t R i d g e

L o n g V a l l e y

R i d g e

High Valley Ridge

Buck Rid g e

H o g b a c k

R i d g e

Boundary

Ridge

Traft Ridge

Benson Ridge Sulphur Bank Ridge

Per k in s C reek

Ridge

H i g h V a l l e y R i d g e

Wolf

Creek

Rid ge

Walker Ridge

Blue Ridge

County Line Ridge

Cache Creek

Ridge

Little Blue Ridge

Camel Back

Ridge

B e a r W a l l o w R i d g e

5000

4000

5000

3000

5000

4000

2000

1000

5000

4000

4000

3000

3000

3000

5000

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4000

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2000

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2 1

3

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8 7

6

11 10 9

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13 14

16 15

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40 41

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66 67 68 69

70 71

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114 115 116 117

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119 120

121 122

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127 128

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131 130

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138 140

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147

142 144

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139 143

148 149

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155 156 157 159 158

161 160

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171

172

173

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175

176

177

178 180 179 181

182

183 184

186 185 187 188 189 190

•

•

•

•

•

Clear Lake

WILSON

FAULT

Little Indian Valley Reservoir

75

22

89

66

64

74

52 75

80

56

69

79

45

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73

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0

65

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19

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82

31

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55

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33

39

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23

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31

36

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10

50

60

Middle

For k

Eel

Ri ver

Eel

Riv e r

Lake Pillsbury

BUCKNELL

CREEK

FAULT

ZONE

BAD

RIDGE FA

U

LT

ZONE

CROSS

S

P

RIN

G

S

FAULT

ZONE

LITTLE

INDIAN VALLEY FAULT ZONE

KENNEDY

FAULT

HUNTING

FAULT

SULFUR

BANK FAULT ZONE

PACIFIC

RIDGE

FAULT

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3395

Sheet 1of 2

Pamphlet accompanies map

APPROXIMATE MEAN

DECLINATION AT CENTER 

OF MAP, 2018 

14 °

HTRONCITENGAM

TRUE NORTH

CALIF.

MAP LOCATION

Framework Geologic Map and Structure Sections along the Bartlett Springs Fault Zone

and Adjacent Area from Round Valley to Wilbur Springs, Northern Coast Ranges, California

By

Robert J. McLaughlin1, Barry C. Moring1, Christopher S. Hitchcock2, and Zenon C. Valin1

2018

Bases: Shaded relief and contours from National 

Atlas

Culture from U.S. Geological Survey, 1 ̊ x 1 ̊: 

Ukiah East, Ukiah West, Santa Rosa East, and 

Santa Rosa West

Universal Transverse Mercator projection, Zone 

10, NAD 83

Geology compiled by R.J. McLaughlin and B.C. 

Moring, 2011–2017; minor field revisions, 

2013–2014. Quaternary geology mapped by 

C.S. Hitchcock, 2012–2016

GIS database and digital cartography by B.C. 

Moring

Edited by J.L. Zigler; digital cartographic 

production by Katie Sullivan

Manuscript approved for publication January 

10, 2018

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

This map is offered as an online-only, digital publication. Users should be 

aware that, because of differences in rendering processes and pixel 

resolution, some slight distortion of scale may occur when viewing it on a 

computer screen or when printing it on an electronic plotter, even when it is 

viewed or printed at its intended publication scale

Digital files available at https://doi.org/10.3133/sim3395

Suggested citation: McLaughlin, R.J., Moring, B.C., Hitchcock, C.S., and 

Valin, Z.N., 2018, Framework geologic map and structure sections along the 

Bartlett Springs Fault Zone and adjacent area from Round Valley to Wilbur 

Springs, northern Coast Ranges, California: U.S. Geological Survey 

Scientific Investigations Map 3395, pamphlet 60 p., 2 sheets, scale 1:100,000, 

https://doi.org/10.3133/sim3395.

ISSN 2329-132X (online)

https://doi.org/10.3133/sim3395

1

U.S. Geological Survey;

2

InfraTerra, Inc.

122°30' 122°22'30"

39°37'30"

39°30'

39°22'30"

39°15'

39°7'30"

39°

123°15' 123°7'30" 123° 122°52'30" 122°45' 122°37'30" 122°30' 122°22'30"

39°

39°15'

39°7'30"

39°30'

39°22'30"

39°45'

39°37'30"

123°15' 123°7'30" 123° 122°52'30" 122°45' 122°37'30"

CONTOUR INTERVAL 400 FEET

A

A'

B"

C'

B'

E

E'

D'

B

C

D

SNOW

MOUNTAIN

WILDERNESS

YUKI

WILDERNESS

YUKI

WILDERNESS

SANHEDRIN

WILDERNESS

MENDOCINO

NATIONAL FOREST

MENDOCINO

NATIONAL FOREST

L A K E C O

C O L U S A C O

L A K E

C O

Y O L O

C

O

LAKE CO

GLENN CO

GLENN CO

MENDOCINO CO

COLUSA CO

GLENN CO

COLUSA CO

YOLO CO

125 ̊ 124 ̊ 123 ̊ 122 ̊

36 ̊

37 ̊

38 ̊

39 ̊

40 ̊

41 ̊

PACIFIC 

PLATE

GORDA–JUAN DE 

FUCA PLATE

NORTH AMERICAN PLATE

MAAC

HLDS 

MAAC

RC 

HAY

GRN

WN

CGV

CAL

PA

0

0 10 20 30 MILES

20 40 60 KILOMETERS

AREA OF MAP

Weaverville

Redding

Red Bluff

Willows

Point Arena

Point Reyes

Lake 

Pillsbury

Cape Mendocino

Clear Lake

Lake

Berryessa

Santa Rosa

Ukiah 

Valley

San Francisco

San Jose

Hollister

Santa Cruz

Salinas

Monterey

Willits

Covelo

MENDOCINO FRACTURE ZONE

 FAULT

SAN

ANDREAS

Point Delgada

Ohlin and

others, 2010

Eureka 

PA C I F I C

O C E A N

BARTLETT

SPRINGS

FAULT

ZONE

Figure 1. Map showing location of the map area, the Lake Pillsbury study area of Ohlin and others (2010), 

the Bartlett Springs Fault Zone (red), and other major faults (black) east of the San Andreas Fault (thick red) 

in the Coast Ranges of northern California. Abbreviations for faults, delineated generally from north to south: 

MAAC, Maacama; HLDS, Healdsburg; RC, Rodgers Creek; WN, West Napa; CGV, Concord-Green Valley; GRN, 

Greenville; HAY, Hayward; CAL, Calaveras; PA, Paicines. Teeth indicate thrust faults; arrows show relative 

movement. Neogene volcanic rocks east of San Andreas Fault are shown in pink. Other features shown are 

structural basins (yellow) associated with active strike-slip faulting and selected folds (white) associated with 

active compression. Geologic features are derived mainly from 1:750,000 geologic map of California (Jennings, 

1977), revised locally.

123°15' 123° 122°45' 122°30' 122°15'

39°45'

39°30'

39°15'

39°

Clear

Lake

Little 

Indian 

Valley 

Reservoir

AREA OF

MAP

Lake

Pillsbury

Ukiah

Willits

Lakeport

Covelo

Figure 3. Location of map area in northern California plotted on 30-m hillshade base, showing 

principal access roads and nearby towns. U.S. and State Highways (paved roads), shown as 

red lines; U.S. Forest Service Routes and county roads (paved and gravel roads) shown as 

brown lines. Berryessa-Snow Mountain National Monument is shaded green.

162

162

162

162

20

20

20 20

128 253

53

53

29

29

175

175

175 116

101

101

101

M1

M1

M10

M1

M61 M6

20

101

M1

U.S. Highway

State Highway

U.S. Forest Service Road

EXPLANATION

Basin fills, lacustrine and alluvial deposits (Holocene and 

Pleistocene)

Deformed fluvial and lacustrine deposits in Clear Lake, 

Lake Pillsbury, and Covelo Valley areas (Pleistocene 

and Late Pliocene)

Clear Lake Volcanics (2.2–0.03 Ma)

Marine and nonmarine basin deposits (Pliocene to middle 

Miocene)

Marine sandstone and shale (Eocene and late Paleocene)

GREAT VALLEY COMPLEX (CRETACEOUS AND JURASSIC)

Limestones associated with deep marine cold seep deposits, 

that contain Peregrinella whitneyi (Lower Cretaceous, 

Hauterivian)

Sedimentary serpentinite intercalated in Lower Cretaceous 

Great Valley Complex (Lower Cretaceous, 

Hauterivian)

Lower Cretaceous and younger marine sedimentary rocks of 

Great Valley Complex (Valanginian and younger)

Lower Cretaceous and Jurassic marine sedimentary rocks of 

Great Valley Complex (Valanginian to Kimmeridgean)

Rocks of the Coast Range ophiolite (Jurassic) + ophiolitic 

mélange (Lower Cretaceous)—Mélange is composed of 

tectonically disrupted lower Great Valley Sequence strata 

(Valanginian to Tithonian) mixed with Jurassic rocks of 

the Coast Range ophiolite; age based on earliest time of 

tectonic mixing

Igneous and metasedimentary basement rocks of the 

Klamath Mountains (Jurassic and older)

BELTS OF THE FRANCISCAN COMPLEX 

(MESOZOIC–QUATERNARY)

Eastern Belt (Middle Cretaceous–Jurassic)—Includes Pickett 

Peak and Yolla Bolly terranes and related rocks 

metamorphosed to blueschist grade; at least three stages 

of blueschist metamorphism represented (155–170Ma; 

~123 Ma; and ~90 Ma)

Snow Mountain igneous Complex (Jurassic)—Mafic and 

alkalic metaigneous rocks here considered part of the of 

the Eastern Belt

Central Belt (Early Tertiary?)—Largely melange, regionally 

assembled between Late Cretaceous (Cenomanian) and 

early Tertiary (Eocene)

Coastal Belt (Tertiary and younger)—Includes rocks latest 

Cretaceous (Maestrichtean–Campanian) to Miocene (~16 

Ma) onshore. Probably includes younger accretionary 

strata in offshore area north of Cape Mendocino

?

?

?

?

0

0 5 10 15 MILES

10 20 30 KILOMETERS

41 ̊

40 ̊

39 ̊

125 ̊ 124 ̊ 123 ̊

NORTH 

AMERICAN

PLATE

GORDA PLATE

SAN ANDREAS FAULT ZONE

? ?

?

PACIFIC

PLATE

? ?

Undivided rocks west 

of San Andreas Fault

AREA OF

MAP

Cape Mendocino

Eureka

Point Delgada

Garberville

Covelo

Snow

Mountain 

Middle Mountain

Lake Pillsbury

Clear

Lake

Ukiah

Willits

Laytonville

Hull 

Mountain

Wilbur 

Point Arena Springs

Fort Bragg

Little Indian 

Valley Res.

Hopland Lakeport

Potter

Valley

Stonyford

Ohlin 

and

others, 

2010

PA C I F I C

O C E A N

BARTLETT

SPRINGS

FAULT

ZONE

MAACAMA

FAULT

ZONE

MENDOCINO FRACTURE ZONE

CASCADIA

MEGATHRUST

Figure 4. Generalized geologic map of northern California showing location of map area, the 

Lake Pillsbury study area of Ohlin and others (2010), the Bartlett Springs Fault Zone, the 

Maacama Fault Zone, and the distribution of principal belts of the Franciscan Complex. 

Eastern Belt of the Franciscan Complex includes rocks of the Yolla Bolly, Pickett Peak, and 

East Clear Lake terranes. The active Bartlett Springs and Maacama Fault Zones shown in 

red; other faults in black. Teeth delineate thrust fault; arrows show relative motion; queries 

show where location uncertain. Regional extent of Bartlett Springs Fault Zone is based, in 

part, on Lienkaemper (2010). Geology north of Lake Pillsbury is largely from McLaughlin and 

others (2000), Jayko and others (1989), and Blake and others (1992, 2000). Geology 

surrounding Lake Pillsbury is based on Ohlin and others (2010). Geology around north and 

southeast sides of Clear Lake incorporates unpublished fieldwork by McLaughlin 

(1979–1981). Area south of Covelo is compiled from McLaughlin and others (1990), Suppe 

and Foland (1978), Hearn and others (1995), Jennings and Strand (1960), and Wagner and 

Bortugno (1982).