Sibley Volcanic Regional Preserve N ORINDA O D Y

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R A R 24 TO C Massive basalt was removed from this major HOW MANY VOLCANOES? Besides Round MORAGA ROAD FISH T Sibley Volcanic RS 5 quarry pit. The north wall shows a set of thick lava Top, there are smaller ones outside the Preserve RANCH Huckleberry PINEHU WILDCAT CYN. ROAD Sibley Botanic Reg. Volcanic Redwood Regional Park . Preserve flows tilted on edge, nearly vertical. The well-defined to the north and southeast. Another, of rhyodacitic Tilden RegionalRK DR ParkBL. Preserve

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SK . Roberts Regional Preserve BOTANIC Y layers near the top of the face are jointing-units composition, underlies the Lawrence Berkeley Labo- LINE D Regional D BL. PEAK R SKYLINE GARDEN R Rec. Area

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ratory and Little Grizzly Peak in . Canyon Reg. Y N I . resulting from shrinkage caused by cooling. They are E

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Preserve A Q E ROAD BART R C L A L Oakland, Berkeley, Orinda O I D analogous to the basalt pillars of Devil’s Postpile in About 9.8 million years ago it was erupting beside BERKELEY J M O 13 WO CLAREMONT AV. D Temescal L E

I R OXFORD AV. the southern Sierra. Round Top. Subsequently it was shifted about three N Reg.Rec. PARK SHA TELEGRAPH AV. C AV. Area Y O TTUCK AV. A L This is a sequence of basaltic tuffs (ash) lying on and one-half miles northwest by movement along N W

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6 35TH top of a dark lava (far left), all tilted steeply to the Wildcat Fault. That makes a total of four volcanoes. O MORAGA AV. R GR B A HIGH N BROAD WAY D FRUITVALE AV. east. The base of the tuffs was baked red, probably THIS PRESERVE is named to honor Robert Sibley, A V . ST. because the lava below was still hot and steaming AV. a founder and director of the East Bay Regional Park SAN ASHBY PA BLO AV. AV. when the ash landed. At the top of the sequence UNIVERSITY District, and president of the Board of Directors from 580 13 Lake ST. 880 there is another lava flow (far right, to the right of 1948 until his death in 1958. The original 227-acre Merritt E. 14TH McLaughlin HIGH ST. the post) that baked the underlying tuffs red. Eastshore Preserve was dedicated with Tilden Regional Park and AV. State Park 980 PARK ST. Before you is a basalt flow, massive at left, rubbly Temescal Regional Recreation Area in October 1936, 7 GRAND to the right. The lower parts, coming into contact 61 WEBSTER ALAMEDA two years after the Park District’s formation. Vari- North 880 with cold land surfaces, harden early and are often ous parcels have been added to the preserve over the 80 ENCINAL AV. 0 1 2 Miles McKAY CENTRALAV. Crown Beach jumbled by turbulence and drag. The rubbly part of years, including a 250-acre parcel in 2010. AV. & Crab Cove the flow is filled with vesicles caused by gas pockets, At the southern park boundary is 240-acre Huckle- which were later filled with chalcedony, opal, calcite, berry Botanic Regional Preserve. The Skyline National To Reach Sibley Volcanic Regional Preserve: zeolites, and sometimes green celadonite. Recreation Trail, which connects Richmond-El So- From Highway 24 just east of the Caldecott Tunnel, This huge, reddish-brown block of lava fell from the brante to Castro Valley, traverses both of these parks. take the Fish Ranch Road exit and go north, uphill, for 8 cliffs to the upper right. The lava cooled and hard- 0.8 miles to Grizzly Peak Blvd. Turn left and go 2.4 WELCOME! Please enjoy the Regional Parks safely, and ened while it was still moving, resulting in dramatic frag- miles to Skyline Boulevard. Turn left on Skyline and help us protect and preserve your parklands by complying with proceed to the park entrance, on the left. PUBLIC mentation, known as “autobrecciation” (self-broken). park rules and regulations. Photo by Michael Short See hard lava to the right and left, and soft, easily SAFETY and ETIQUETTE TRANSIT: The closest bus line is AC Transit #18, 9 eroded tuff between, all tilted eastward almost to • Stay on trails. Taking shortcuts can be dangerous and which runs to the Montclair Transit Center in Mont- vertical. The lava to the left baked the top of the tuffs causes erosion. clair. From 12th Street BART or 19th Street BART, brick red. This lava looks as if it was probably 100-150 • Wading and/or swimming in undesignated areas may be take AC Transit bus #18 to the Montclair Transit dangerous and may harm the watershed. Center. Call AC Transit to confirm transit information: feet thick. These flows were not fluid, but contained • Carry and drink plenty of water. Dehydration is a leading dial 511 (TDD/TTY: 1-800-448-9790). enough silica to be more viscous. They probably cause of injuries on the trail. moved at a slow walk, with glowing blocks of lava tum- • Be prepared for sudden changes in weather conditions. bling down a steep front and setting vegetation on fire. • Trails can be slippery, rocky and steep. Proceed carefully at your own risk. 10 The brick-red knobs in the foreground, and rug- • Wildlife may be present on the trails at any time. ged outcrops of the same color on the skyline, Feeding or approaching wildlife is dangerous and illegal. are made of cinder that flew from Round Top and • Bicycles are permitted on designated trails only. Horses have the right-of-way on trails. landed while still hot, so the pieces welded together. Photo by Jerry Ting The major valley to the north across Highway • Keep the parks beautiful. Pack out what you pack in. 11 RULES 24 is Siesta Valley. It coincides with the axis of • Dogs must be leashed 200 feet from any trail or park the Siesta Syncline, a great fold that has lifted up entrance. Dogs must be leashed in parking lots, picnic areas, thousands of feet of rocks on both sides. You are developed areas such as lawns and play fields, and on some standing on the southwest limb of the fold, which trails. They must be under voice control at all times. includes all the rocks in Sibley. • State law requires that all bicyclists under age 18 wear an approved helmet while riding on trails and roadways. East Bay Regional Park District Equestrians and bicyclists are also strongly encouraged to wear 2950 Peralta Oaks Court, helmets at all times. POLICE, FIRE, MEDICAL EMERGENCY...... 9-1-1 P.O. Box 5381 • Smoking is prohibited, except in overnight campsites. Oakland, CA 94605-0381 EBRPD HEADQUARTERS...... 1-888-327-2757 • Drones are prohibited. PARK OFFICE...... 1-888-327-2757, option 3, ext. 4554 1-888-327-2757 (1-888-EBPARKS) TRS RELAY FOR THE HEARING IMPAIRED...... 7-1-1 Visitors are responsible for knowing and complying with park www. ebparks.org Rev. 7/17 rules, available online at www.ebparks.org/rules. poppies. Photo by Isa Polt-Jones A B C D E F G H I J K L

24 EBMUD WATERSHED. DOGS AND HORSES ARE NOT Hiking permit required To Walnut Creek 1400 PERMITTED IN HUCKLEBERRY AREA IN YELLOW except when hiking on except passing through on the Skyline National Trail. SUBJECT TO CLOSURE 1 Skyline Trail/Bay Area 11 DOGS MUST BE UNDER VOICE See www.ebparks.org/ Ridge Trail. Call 10 sibley for status. NO ACCESS Quarry Pit 5 CONTROL AT ALL TIMES. BEYOND GATES (510) 287-0459. .11 HORSES MUST STAY 9 .11 4 ON THE SKYLINE TRAIL. 8 7 6 .04 .07 Quarry Pit .06 IC T .14 .28 3 1000 1300 .19 N RA TRAIL 2 .04 CA I VOLC .03 BICYCLES ARE NOT PERMITTED L L ANIC .131500 .11 Trail O IN HUCKLEBERRY FENCELINE V 1400 p .08 .04 .12 AIL L REGIONAL BOTANIC PRESERVE. TR I 1200 .13 .29 A o SIBLEY .03 1100 .15 Y R o .15 R T L QUAR 1300 .51 VOLCANIC P 1600 900 .08 P O .17 r OND R 1500 T .13 O O e REGIONAL R. L 1100 k Q U 1000

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OLD TUNNEL ROAD SIBLEY P N o DOGS ARE NOT PERMITTED U .41 O D 1000

PRESERVE 1700 C A T c T In this section of parkland. R VOLCANIC O FENCELINE

R D P M 900 Old Tunnel Road Private Y 1200 N L .36 FISH RANCH ROAD 1200 REGIONAL PropertyEBMUD O 1000

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.29 miles to Fish Ranch Road. . PRESERVE begins here.

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NO ACCESS 900 1100 R

1.75 miles to Tilden Reg. Park 1100

See descriptions EBMUD 1,763 A BEYOND GATE

I below. 1 L DOGS MUST BE ON LEASH.74 .47 Water Tank from park boundary to Sibley .03 .18 .20 p Creek .18 .08 Sibley staging area on Skyline Bl. nd To Back pack HUCKLEBERRY 800 Rou .02 Wilcox 1200 7 parking spots BA IL Camp .03 .08 BOTANIC Station 800 3 Y ARE TRA .15 1400 To Canyon Road and Moraga S A RIDGE Staging GRIZZLY KYLIN IL 1100 IL REGIONAL E TRA .87 A TERR. DR. R Area T 10 parking spots D K .24 PRESERVE ST ROA 1300 PINEHUR O .22 Separate map available. 800 1300 O A . L ARE R ST TR

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GRIZZLY PEAK OPEN SPACE T E T P L R O R G A AIL 1000 R area is from Canyon Road in E R IL E .22 I 1200 N Z RIDG Moraga, then turn right on Z W 900 EA E TR N L .81 O R A 1000 Y S L A LINE TRA IL Pinehurst Road. U a I n 1100 .12 Y KY L T P L A S E ea B .38 T SKY A n U LIN K SKY dro .32 1100 T E LIN Creek N . E BL N D T B B . .56 E L L R O . 1100 L . 1100 .03 4 R L C E E D N 1200 .11 . N D KLE Y PAT U L HUC BERR H T A .01 .18 OLD C Huckleberry .03 1200 THORNDALE DR. Staging Area .32 1100 Sibley AD PINEHURST RO Lava from the vent has been dated as old as 10.2 Staging 14 parking spots .21 1300 .05 1400 Area S million years. Round Top’s basaltic dikes (feeders of L. K Year opened: 1936 Acres: 928 1000 38 parking spots B YLIN NE E .28 LI BL. Highlights: Hiking, biking, horseback riding, the vents), tuff-breccias (ash containing a jumble of Y K 24 blocks and chunks of lava), lava flows, red-baked S self-guided interpretive tour,OAKLAND backpack camp, LEGEND IPS TRAIL panoramic views. cinder piles, air-fall tuffs, and the major vent itself can PHILL RD. Hikers, Horses & Bicycles Did you know? This parkland was opened as Round all be seen in an easy hike. The numbered descript- SKYLINE BL. N 1200 O Hikers & HorsesREDWOOD ions below correspond to stops along the trail. Y Top in 1936 with the formation of the Park N Fire St. #6 A REGIONAL PARK TO C SARONI C Symbol denotes Skyline Trail/ Walk up the paved road to the EBMUD water caused by oxidation of iron in theO sediments. Such Separate map available. District. It was renamed in 1972 to honor Robert S L 1 MONTCLAIR N T D Bay Area Ridge Trail O R tank to see a dark basalt dike, a feeder of lava to varicolored “redbeds” sometimesA contain fossils of plants and E N DR. S WEST RIDGE TRAIL W. Sibley, a Park District founder and director. E K H EVERGREEN TR DG EA I E P AVE. Hikers Only R L DR. E the crater, that cuts through a sequence of tuff- animals.IL Elsewhere in the Preserve, bands of more intense Skyline M 1100

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H N .28Gate, T . Mileage BetweenR Points breccias (grayish brown) and pebbly mudstonesT WAY R red are found ACat the Transit tops #305 and bottoms of lava flows, where Redwood A A LN. E O I A SELF-GUIDED TOUR H H DR. Reg. Park L (light gray), inside and near the crater bottom. T iron was oxidized and reddened by baking and steam action; Paved Road OF ROUND TOP VOLCANOES This pit was made by quarry operations in which these bands are called “bake zones.” Parking 2 North By Stephen W. Edwards massive basalt lava was removed. The pit exposes 4 Before you is a wall with basalt on the left and Orinda Restrooms Former Director, Regional Parks Botanic Garden the interior of the Round Top volcano. You are stand- mudstones on the right. The bedding in the mud- Visitor Center This Preserve features a complex volcanic center ing on bedded tuff-breccias, which filled much of the stones gives the appearance of drag-folding resulting from Drinking Water that was the source, 10 million years ago, of most of crater, settling at times into a small lake. The steep relative uplift of the lava occurring during the past 10 Information Panel the lavas that underlie the ridges from Inspiration wall across the pit consists of lava that capped the million years. Alternatively, the disruption of the Backpack Camp Point in Tilden Regional Park to Moraga. Round Top crater after it was filled. Eventually the Round Top mudstones may have occurred earlier, at the time of 4 Self-Guided Tour Stops stands out today because it was originally surround- vent buried itself in basalt flows. volcanic activity. This site was close to, or was in, the wall Rev. 7/17 Rev. Gate, No Vehicle Access ed by sedimentary rocks of the Orinda Formation, This roadcut exposes Orinda Formation river of the volcano, and would have been subject to slumping, SKYLINE 0 1/8 1/4 3/8 Mile which have eroded away. Over the years, folding and 3 gravels, sands, and mudstones. The red (when sliding, and plowing. erosion have exposed a cross section of a volcano. moist) streaks and layers in these river beds were Continued on reverse Contour Interval 10 feet BL.