A geological look at the Oakland Hills regional parks.

1. History and Geology of the
Oakland Hills
Home to the East Bay’s Urban
Redwood Forest
Susan Gard
Professor Lawler
Geology 103, Summer 2014
Aug. 3, 2014

2. Presentation Contents
• Geologic history of area
• Observable rocks
• Redwood Regional Park
• Redwood Regional Park fauna
• Redwood Regional Park flora

3. Background and Methodology
• I live below the Oakland Hills and visit East Bay Regional
Parks regularly with my dog
• Information for report gathered on visits to various sites
within hills parks including:
– Redwood Regional Park
– Robert Sibley Volcanic
Regional Preserve
– Joaquin Miller Park
• Some photos are mine
and some come from
online research

4. Geologic History of Oakland Hills
• Region first at floor of Pacific Ocean—later
covered in shallow seas
• 12 million years ago became coastal lowland filled
by sediment
• Active continental margin:
– Pacific plate drifting eastward
– North American plate drifting
westward
• Pacific plate sinks into
mantle where two plates
come together

5. Geologic History of Oakland Hills
• Eight to 10 million years ago volcanos covered
lowlands with thick basalt lava flows
• Four million years later force of transpression
made lowlands begin to rise
• Tilted up to and beyond vertical in some
places (Rademacher 2012)

6. Geologic History of Oakland Hills
• One million years ago reached current heights
• Still rising about 1/16 inch/year squeezed
between Hayward fault to west and Calaveras
fault to east
• Actual growth minimal because erosion nearly
balances tectonic uplift

7. Basalt Lava
• Abundant in Robert Sibley Volcanic Regional Park
• Hard, dense, dark volcanic rock
• Dated at UC
• Berkeley—
10.2 million
years old
(Edwards)
• Quarried in
modern times

8. Breccia
• Many varieties of breccia in Sibley:
– Tuff breccia—volcanic ash hardened to stone
containing jumble of blocks and chunks of lava
– Basaltic breccia—composed of fragments of basalt
and other rocks cemented together
– Autoclastic basaltic breccia—basaltic breccia
formed in place by grinding of dike rock

9. Chert
• A microcrystalline or cryptocrystalline
sedimentary rock material composed of silicon
dioxide
• Formed when
microcrystals of
silicon dioxide
grew within
soft sediments
(Geology.com)

10. Actinolite Schist
• Found in Joaquin Miller Regional Park
• Foliated metamorphic rock dominated by the mineral
actinolite
• Actinolite: dark
greenish-colored
amphibole calcium
Ferromagnesian
hydroxy-silicate
that forms long
blades or
needle-like crystals
(St. John)

11. Serpentinite
• Composed of one or more serpentine group minerals
• Metamorphic version of peridotite—deep-seated, low-silica
rock that forms upper mantle and bottom of oceanic plates
• Study of serpentinite in
California contributed to
understanding of modern
plate tectonic theory
• Unique association with
California due to gold
deposits and thought to
promote slower ‘creep’
along faults
(Romans 2010)

12. Serpentine Prairie
• Many unique plants grow in serpentinite-rich
soils
• Redwood Regional Park’s Serpentine Prairie
home to rich array of native plants

13. Redwood Regional Park
• Millions of years ago
redwood trees found
across North America
• Drying and cooling
climates preceding last
Ice Age drove redwoods
to Pacific Coast
• Now only survive in narrow
fog-influenced belt
• Climate in East Bay Hills
generally too arid

14. Redwood Regional Park
• Adapted to catch summer
fog in needles and drip it
down to roots
• Today’s redwoods
second and third
generation clones of
ancient giants
• Redwood forest supports
unique ecosystem
(Slack 2004)

15. Redwood Regional Park Fauna
• Steelhead trout found and named in Redwood Creek in
1855
• Redwood Creek cut off from
San Francisco Bay in 1869
• Steelhead and rainbow trout
same species, but steelhead
metabolically morph to tolerate
salt water and return to fresh
water to spawn
• Current rainbow trout in creek
direct descendants of steelhead

16. Redwood Regional Park Fauna
• California or coastal newt (taricha torosa) 10 million years old
• Amphibious—must stay near water because no amniotic egg
• Glands in skin secrete potent neurotoxin tetrodotoxin
• Garter snake only natural predator
• Evolved resistance to tetrodotoxin
• Locked in “arms race” as
tetrodotoxin-resistant snakes
cause natural selection to favor
ever-more poisonous newts and
more poisonous newts drive selection
for higher resistance in snakes
(Shelby 2008)

17. Convergent Ladybird Beetle
• Feed on aphids and other soft-bodied insects in
grasslands and Bay wetlands
• When rains stop and prey begin to disappear fly to
ancestral spots in East Bay Hills
• Not understood how know to fly to specific
ancestral sites
• Enter energy-saving semi-hibernative state
• Clusters in Redwood Park in March contain
hundreds of thousands of insects (Bauer 2007)
• http://science.kqed.org/quest/video/ladybug-
pajama-party/

18. Redwood Regional Park Flora
• Forest also supports evergreens, chaparral and
grasslands
• Western trillium, native wild-ginger, yellow
stream violet and wood violet abundant

19. References
Bauer, Chris Feb 27, 2007. Ladybug Pajama Party Video Story for QUEST Northern California
Romans, Brian Aug 5, 2010. Learn the Facts About Serpentinite Before It's Removed as California's
State Rock. Retrieved From: http://science.kqed.org/quest/2010/08/05/learn-the-facts-about-
serpentinite-before-its-removed-as-californias-state-rock/
Slack, Gordy July 1, 2004. In the Shadow of Giants: The Redwoods of the Oakland Hills. Bay Nature.
Retrieved From: http://baynature.org/articles/in-the-shadow-of-giants/
Oakland Geology. Retrieved From: http://oaklandgeology.wordpress.com/
Rademacher, Horst January 6, 2012. From the Inside Out: Digging the Geology of the East Bay Hills.
Bay Nature. Retrieved From: http://baynature.org/articles/from-the-inside-out/
Martin, Shelby March 12, 2008. Snakes slither past toxic newts in evolving race. Stanford News.
Retrieved From: http://news.stanford.edu/news/2008/march12/newts-031208.html
Edwards, Stephen. A Self-Guided Tour of Round Top Volcanoes. Retrieved From:
http://www.ebparks.org/Assets/_Nav_Categories/Parks/Maps/Sibley+map.pdf
Geology.com. What Is Chert, How Does It Form and What Is It Used For? Retrieved From
http://geology.com/rocks/chert.shtml
St. John, James. OSU-Newark Geology. Retrieved From:
http://www.newark.osu.edu/facultystaff/personal/jstjohn/Documents/Home-page.htm