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
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1600 BAY AREA RIDGE TRAIL 24 IN ORDER TO REDUCE OR LEGEND PREVENT THE RISK OF SERIOUS EBMUD WATERSHED. To Walnut Creek HEAD INJURY OR DEATH, STATE Hikers, Horses & Bicycles SKYL 1500 Hiking permit required 1400 LAW REQUIRES THAT ALL INE Hikers & Horses TRAIL except when hiking on BICYCLISTS UNDER AGE 18 WEAR G 1400 AN APPROVED HELMET WHILE Skyline Trail/Bay Area Ridge RI Water Skyline Trail/Bay Area 11 ZZ Tank 10 1500 RIDING ON TRAILS AND ROAD- LY Ridge Trail. Call Quarry Pit 5 Trail–Hikers & Horses PE .11 AK 13 WAYS. THE DISTRICT ALSO BL 00 (510) 287-0459. 9 .11 4 . 8 .04 Quarry Pit STRONGLY RECOMMENDS THAT Hikers Only 7 6 .28 .07 .19 ICT .14 ALL EQUESTRIANS AND 1300 .06 N R TRAI 3 2 .28 AREMONT AV A A VOL .03 .11 .04 Mileage Between Points CL . LC IL CANIC L .13 BICYCLISTS WEAR HELMETS AT O V 1400 ALL TIMES. Paved Road .04 .12 AIL LOOP .13 .08 TR .29 1.46 mi. from SIBLEY .15 Y Fish Ranch Road .15 QUARR 1300 DOGS AND HORSES ARE NOT Parking UNIVERSITY to Lomas Cantadas VOLCANIC 1600 TRAIL North PON .08 SIBLEY .17 D T 1500 and Tilden1200 Reg. Park R. TOP PERMITTED IN HUCKLEBERRY 13 Restrooms OF REGIONAL . OLD TUNNEL ROAD .29 VOLCANIC except passing through on the CALIFORNIA PRESERVE Q .41 Skyline National Trail/Bay Area Visitor Center U REGIONAL te 17 . 00 36 BERKELEY A ROUND va Ridge Trail. R 200 PRESERVE Pri Drinking Water RANCH ROAD 1200 R 1 PropertyEBMUD FISH Y BICYCLES ARE NOT PERMITTED R Self-guided tour 1.08 D Round Top IN HUCKLEBERRY PRESERVE. Information 1100 1100 . begins here. EBMUD 1,763 Descriptions below. 1 4 Self-Guided Tour Stops DOGS MUST BE ON SKYLINE TRAIL from park boundar .47 Water Tank .18 .03 Gate, No Vehicle Access Sibley staging LEASH nd Top Creek .08 HUCKLEBERRY Rou .02 y to 12 BA IL .1 .03 .08 area on Skyline Bl. 00 Y A RA 5 1400 BOTANIC 0 1/4 1/2 Mile RE T A RIDGE .87 GRIZ 1100 REGIONAL GRIZZLY PEAK ZLY .24 TERR. DR. PRESERVE Contour Interval 20 feet in Claremont Canyon, Redwood, CLAREMONT M 1300 PINEHURST ROAD A .22 800 and Sibley triangle west of Thorndale Dr. R 1300 CANYON L 1100 Contour interval 10 feet elsewhere. B .81 O G OPEN SPACE R SKY REGIONAL R L 1000 .22 IZ IN O Z 120 E L 0 B PRESERVE U BL. Y AY AR 900 1000 N EA R G S IDG L TUNNEL I a E TRA .12 O P n 1100 8 H TRAIL TUNNEL RD. EA Le .3 R an K dro P F T SKYLINE Creek O I E BL. .56 N M L RD. B .32 DR L R L OBSER .03 E A S . 1 . DIABLO 100 11 R K H K VATION PL. O H DR. 1200 O G Y E CKLE RY PAT U L BER H L U R M R N H 8 I H I V 1 D. S AT N . R K 0 E .01 1300 T T S E Huckleberry .03 C R OLD TUNNE THORNDALE DR. R T .32 U 110 D B O Sibley Staging B L N Area .05 .21 . D Staging 400 R. 1 1000 Area .28 CALDECOTT O DR. 1200 A VILLANOVADR. L IL K A B R W T MANZANITA L. GE OAKLAND DR. O SKYLINE B RID . O E TRAIL D D N EAST LLIPS R LI PHI RD. Y GLE K TE N O N S A SELF-GUIDED TOUR Hence, folding and erosion have exposed a cross N A DR. O 1200 A WY K ARROWHEAD Y R . S N B A REDWOOD section of a volcano, right down to its roots, O Fire St. #6 C DR. C TO MOO OF ROUND TOP VOLCANOES S O RT SA S U N REGIONAL PARK L ENCO RONI MONTCLAIR N GL D providing an unsurpassed outdoor laboratory for the T N R A O Skyline GE DR. U E ST WEST RIDGE TRAIL ID N HOMEGLEN RE R K G H R A ILL P Gate By Stephen W. Edwards study of volcanism in the Central Coast Ranges. R DR. E E 1100 E E H M DR. H N R H R RIDGEWOOD T S Director, Regional Parks Botanic Garden T D RA A WAY O AC Transit #305 LN. The blocks of stone scattered everywhere around E . I H H DR. DR. L Robert Sibley Volcanic Regional Preserve features a the flanks of Round Top are basalt lava (a hard, dense, T complex volcanic center that was the source, 10 dark volcanic rock). Lava from the vent has been million years ago, of most of the lavas that underlie dated at UC Berkeley by the potassium-argon radio- mudstones (light gray), all inside and near the bottom of the This roadcut exposes Orinda Formation river gravels, the ridges from Inspiration Point in Tilden Regional isotopic dating method. The oldest is 10.2 million crater. The mudstones indicate ponding of water; the tuff- 3 sands, and mudstones. The red (when moist) streaks Park to Moraga. Round Top, one of the highest peaks years old. breccias are the remains of landslides and blockfalls into the and layers in these river beds were caused by oxidation of in the Berkeley Hills, consists of lavas, breccias A great diversity of volcanic phenomena is pre- pit from the surrounding walls. iron in the sediments. Such varicolored “redbeds” are (unsorted mixtures of fine and coarse volcanic served for study at Sibley. Basaltic dikes (feeders of This pit was made by quarry operations in which huge explored worldwide for the fossils of plants and animals debris) and tuffs (lithified volcanic ash – ash that has the vents), tuff-breccias (ash containing a jumble of 2 amounts of massive basalt lava were removed. The result they contain. Elsewhere in the Preserve, bandsSKYLINE of more become stone) that once filled a volcano. blocks and chunks of lava), lava flows, red-baked is a tremendous boon to geology, for the pit exposes the intense red are found at the tops and bottoms of lava Though Round Top was once the infilling of a great cinder piles, air-fall tuffs, and the major vent itself can interior of the Round Top volcano. You are standing on flows. In such cases iron was oxidized and reddened byBL. crater, it stands out today because it was originally all be seen first-hand in the course of an easy hike. bedded tuff-breccias, which filled much of the crater, settling baking and steam action; these bands are called “bake surrounded by “incompetent” (easily eroded) Numbered posts, which correspond to the at times into a small lake. Studies of exposures north and zones.” A related process occurs when a brushfire sedimentary rocks of the Orinda Formation, which numbered descriptions below, have been placed at south suggest the crater was a little wider than the present reddens rocks and soil. To see Post 4, walk about 100 feet have eroded away. During the past 10 million years some of the most interesting outcrops. quarry pit. The steep wall across the pit consists of lava that past Post 3, then bear to the right. the Berkeley Hills were uplifted on a gigantic scale To visit this site, walk up the paved road to the capped the crater after it was filled. Eventually the Round Before you is a wall with basalt on the left and Orinda 1 because of strains on the Hayward and Moraga fault EBMUD water tank. A dark basalt dike, an Top vent buried itself in basalt flows. From this point, note 4 mudstones on the right. The bedding in the mudstones systems. This uplift folded the rock formations, and important feeder of lava to the crater, cuts through a the view of Mt. Diablo, which, though it contains some the Round Top vent complex was tilted on its side. sequence of tuff-breccias (grayish brown) and pebbly submarine volcanic rocks, never was a volcano. Continued on reverse.