1200

TRAIL

L

I BL.

S

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P

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North T

L

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G P IL R 1100 A

RST D. D U I R

EH T IN R

P WEST RIDGE TRAIL SKYLINE

A M

E REDWOOD REGIONAL PARK R

EAST T

S

200

1

1/4 1/2 Mile .28 PINEHURST ROAD PINEHURST

LEGEND Hikers, Horses & Bicycles Hikers & Horses Area Ridge Skyline Trail/Bay & Horses Trail–Hikers Hikers Only Mileage Between Points Paved Road Parking Restrooms Center Visitor Drinking Water Information Stops Self-Guided Tour Access Gate, No Vehicle

B L

.

E

4 8

N

1 .

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L Skyline Gate

Contour interval 10 feet elsewhere.

Y

K S and Sibley triangle west of Thorndale Dr.

.28

8

DR.

1000 3

.

800 Contour Interval 20 feet in Claremont Canyon, Redwood, RD.

0

1300

N

O MOORE Y

N

A

11 C .

D

.01 R E

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.03 P E H

DR. S

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U

G

. DR.

L

B 900

.21

.22

100

1 E .03 1000 gravels, river exposes Orinda Formation This roadcut is a wall with basalt on the left and Orinda you Before

TRAIL N

I .56

L

Y RONI 3 (when moist) streaks The red and mudstones. sands, of oxidation caused by beds were in these river and layers are “redbeds” Such varicolored in the sediments. iron of plants and animals the fossils for worldwide explored bands of more in the Preserve, Elsewhere contain. they at the tops and bottoms of lava found are intense red by and reddened was oxidized In such cases iron flows. “bake called these bands are baking and steam action; occurs when a brushfire process A related zones.” walk about 100 feet 4, see Post To and soil. rocks reddens then bear to the right. 3, past Post 4 in the mudstones The bedding on the right. mudstones Continued on reverse

K

E S SA DR. IN H

L .12 T

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T LN.

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R T O

DOGS AND HORSES ARE NOT PERMITTED IN HUCKLEBERRY except passing through on the Area Skyline National Trail/Bay Ridge Trail. BICYCLES ARE NOT PERMITTED PRESERVE. IN HUCKLEBERRY

DR. D

E

C

HUCKLEBERRY BOTANIC REGIONAL PRESERVE

E .32

B N

G D E IN ORDER TO REDUCE OR PREVENT THE RISK OF SERIOUS STATE OR DEATH, HEAD INJURY ALL REQUIRES THAT LAW BICYCLISTS UNDER AGE 18 WEAR AN APPROVED HELMET WHILE RIDING ON TRAILS AND ROAD- THE DISTRICT ALSO WAYS. RECOMMENDS THAT STRONGLY ALL EQUESTRIANS AND BICYCLISTS WEAR HELMETS AT ALL TIMES. 1100 E

D L L

A HOMEGLEN

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G

E K R

C

H

MANZANITA .32

A

U

E W H

R O

A R RIDGEWOOD DR. .81

R

Y 1200

400

DR. A

A 1

B N k LTO e O R e C D

.05 E .

.36 r K VILLANOVA A 0 C SN

1500 1100

o 120 r

d

n .03 S 00 a K 17 .08 e A L TRAIL O

. N

n D Y .08 O 1300 a O E

S L .17 W

.04 .03 1400 W G K #6 St. Fire A 2

EBMUD

e O DR. 1600 t

Round Top 1,763

AC Transit #305 Transit AC

va 5

.18

OOP Property .

Pri .1

L BL. D

Quarry Pit R

Huckleberry Staging Area

.11

DR.

Water Tank Water .02

TOP

1

EBMUD E

SKYLINE T

N MONTCLAIR TO TO

.22

DIABLO A

ROUND ROUND

DR. R

L

B

L I .41 O

S

.24

.13 H

Sibley Staging Area

3 N

R

L O 4 H

T

E

.07 400 1 G

TRAI D

. I

R

300 R

.04

.03 1

WAY D R

VATION PL. E

1500

N H

O T T A

ER E LV H

OBSER E

.11 C

I

.29 N 5

.87 quarry This pit was made by operations in which huge SIBLEY VOLCANIC REGIONAL PRESERVE A Self-guided tour begins here. Descriptions below. THORNDALE DR. C 2 The result removed. were basalt lava amounts of massive the pit exposes for boon to geology, is a tremendous standing on are You volcano. Top interior of the Round settling of the crater, which filled much tuff-breccias, bedded north Studies of exposures and at times into a small lake. south suggest the crater was a little wider than present that the pit consists of lava The steep wall across quarry pit. the Round Eventually the crater after it was filled. capped note this point, From buried itself in basalt flows. vent Top though it contains some which, Diablo, of Mt. the view was a volcano. never rocks, submarine volcanic mudstones (light gray), all inside and near the bottom of (light gray), mudstones the tuff- indicate ponding of water; The mudstones crater. of landslides and blockfalls into the the remains are breccias walls. the surrounding pit from .28 L L O L I

I k

V A

e A

R 6

e R

T r

T

C

Quarry Pit

7

E

p

N 0

o I

110

Y

T 1000

L

200

1 R

Y

R

K

d

1300 S

A

.12 n

U u L o .14 I Q

A R 8

5 9

R L

1100 T 1 I

. .

A

C D I

R R

10 N .47

Y T

.04 A

.11 R

C R

L

13

. A E

O U .19

V Q G 11

1400

D .15 .08 I

R

A .08 1200 E

R

A .06 .

R 9 Y .13 T 1100 2 A . D B

N 1300 O P . L B

K A E P

LY Z SKY IZ LIN R E G BL.

00

OLD TUNNEL ROAD 12 TUNNEL L RD. L OAKLAND To visit this site, walk up the paved road to the road walk up the paved visit this site, To To Walnut Creek Walnut To

24

Hence, folding and erosion have exposed a cross exposed a cross have and erosion folding Hence, to its roots, right down section of a volcano, an unsurpassed outdoor laboratory the for providing in the Central Coast Ranges. study of volcanism dense, (a hard, basalt lava are around everywhere The blocks of stone scattered Top the flanks of Round has been the vent from Lava rock). dark volcanic radio- the potassium-argon by dated at UC Berkeley The oldest is 10.2 million isotopic dating method. old. years phenomena is pre- of volcanic of (feeders diversity A great Basaltic dikes served study at Sibley. for (ash containing a jumble of tuff-breccias the vents), red-baked flows, lava blocks and chunks of lava), itself can and the major vent tuffs, air-fall cinder piles, all be seen first-hand in the course of an easy hike. to the which correspond posts, Numbered been placed at have descriptions below, numbered outcrops. some of the most interesting 1 an A dark basalt dike, a cuts through EBMUD water tank. to the crater, important of lava feeder and pebbly brown) (grayish sequence of tuff-breccias CALDECOTT

1100 TUNNE OLD

LEASH ROAD y to ZLY

RR. DR.

area on SkylineGRIZ Bl. TE

RANCH SIBLEY VOLCANIC REGIONAL PRESERVE

DOGS MUST BE ON from park boundar Sibley staging

OPEN SPACE FISH

TUNNEL RD.

(510) 287-0459. (510)

Ridge Trail. Call Call Trail. Ridge

Skyline Trail/Bay Area Trail/Bay Skyline

except when hiking on hiking when except

Hiking permit required permit Hiking EBMUD WATERSHED. EBMUD

1200

00 1.08 M

13 A

BL. H

B 1400 U C G K I N GRIZZLY PEAK GRIZZLY 1.46 mi. from Fish Ranch Road to Lomas Cantadas Reg. Park and Tilden

R. D. TE R GH ROU LBO TRAIL R K A OL . M ORF V N NE I A . .

L

Water Tank T B DR

SKYL N BAY AREA RIDGE TRAIL R

O

K O

A M O

E E M

P R H

A 1500 T

OF

Y L

L A

C

Z R

1600 Z T

BERKELEY I S

UNIVERSITY R CALIFORNIA G CLAREMONT CANYON REGIONAL PRESERVE A SELF-GUIDED TOUR TOUR A SELF-GUIDED VOLCANOES TOP OF ROUND Edwards W. By Stephen Botanic Garden Regional Parks Director, a features Regional Preserve Volcanic Robert Sibley 10 center that was the source, complex volcanic that underlie of most the lavas ago, million years Tilden Regional in Inspiration Point the ridges from one of the highest peaks Top, Round Park to Moraga. breccias consists of lavas, Hills, in the Berkeley (unsorted of fine and coarse volcanic mixtures ash – that has debris) and tuffs (lithified volcanic become stone) that once filled a volcano. was once the infilling of a great Top because it was originally it stands out today Though Round crater, eroded) “incompetent” (easily by surrounded which sedimentary of the Orinda Formation, rocks During the past 10 million years away. eroded have uplifted on a gigantic scale Hills were the Berkeley and Moraga fault because of strains on the Hayward and formations, the rock This uplift folded systems. complex was tilted on its side. vent Top the Round