This is the field study of landscapes and life forms of San Luis Obispo

1. Landscapes and
life forms of San
Luis Obispo,
California
A geological study:
By Neha J Pande
Picture by: Neha J Pande

2. San Luis Obispo and the its
place in California
• San Luis Obispo is 190 miles north of Los Angeles and 230
miles south of San Francisco
• The city lies within the southern Coast Range Geomorphic
Province
• The province lies between the Central Valley of California and
the Pacific Ocean and extends from Oregon to northern Santa
Barbara County.
• San Luis Obispo Coast is structurally complex and is comprised
of sub-parallel northwest-southeast trending faults, folds, and
mountain ranges (Wagner, 2002)

3. San Luis Obispo: Then and Now (“San Luis Obispo, California,” 2022)
• The Spanish founded the city of San Luis Obispo on September 1, 1772, when Saint Junípero Serra
established Mission San Luis Obispo de Tolosa (5th of California’s 21 missions)
• San Luis Obispo County is one of the original counties of California, created in 1850 at the time of statehood.
• The Salinas Valley River stretches north from San Luis Obispo County.
• San Luis Obispo is a seismically active area; there are active or potentially active faults, including the San
Andreas Fault.

4. •San Luis Obispo area rocks include volcanic,
metavolcanics, and mélanges of serpentinite and
graywacke sandstone.
•These rocks are highly fractured and are part of the
Mesozoic-aged Franciscan Formation (Smith & Griggs,
1944)
•The most distinctive geomorphological feature of the
San Luis Obispo area is the series of Tertiary aged
volcanic plugs which extend from the City of San Luis
Obispo northwesterly to Morro Bay.
•This string of volcanic plugs are called “the nine
sisters” of which six are open to the public for
recreation (Geology/Hazards, 2004)
Rocks found in San Luis
Obispo
Picture of Morro Rock in San Luis Obispo,
by: Neha J Pande

5. The peaks were created more than 20 million years ago during the Miocene Epoch of
the Neogene Period, as volcanic plugs of magma welled up and solidified inside softer rock
which has since eroded away. (Problogic, 2017)
Morro rock Black Hill Cabrillo peak
Hollister Peak
Cerro Romauldo
Chumash
Peak Bishop Peak
Cerro San
Luis
Islay hill
The “nine sisters” of San Luis Obispo.

6. Identification of rocks #1:
Serpentine
• The rocks looks like Serpentine- (the State
Rock of California).
• Serpentine rock is apple-green to black
and is often mottled with light and dark
colored areas.
• Its surfaces often have a shiny or wax-like
appearance and a slightly soapy feel.
• Serpentine is usually fine-grained and
compact but may be granular, platy, or
fibrous in appearance. (Serpentine:
California’s State Rock, n.d.)
The picture is from Irish Hills on Southwest side of town, a
popular spot for hiking)

7. Serpentine Rocks: History of Formation
• Serpentine is metamorphosed remains of
magnesium-rich igneous rocks, most commonly
the rock peridotite, from the earth’s mantle.
• The theory behind the formation of Serpentine
is that peridotite underlying oceanic crustal
rocks have been metamorphosed to serpentine
in subduction zones that existed at various
times in California’s past.
• A subduction zone is an area where ocean crust
rocks run into and slide underneath the edge of
a continent. Since serpentine has a much lower
density than peridotite, it rose toward the
surface along major regional thrust faults
associated with the subduction zones.
(Serpentine: California’s State Rock, n.d.)
The picture is from Irish Hills on Southwest side of town, a
popular spot for hiking)

8. • The grandest exposures of the Shale Formation in
San Luis Obispo county are at Montaña de Oro
State Park. By looking at them, one could tell they
are shale since it splits into layers parallel to the
bedding plane.
• The rocks consists of many thin layers that are
bound together.
• In my observation I could see the rock formation is
tilted and folded and the layers of rocks that were
deposited over time, showing the succession of
rocks over time.
• Rocks seemed to have been lifted by tectonic
forces after they were deposited.
• They are white and tan or some are yellowish
showing a high content of calcite. (Helmenstine,
2020)
Montana de Oro
state park
Identification of rocks #2 : Shale

9. Identification of rocks #3: Dacite
• This is a picture of rocks on Bishop Peak, another
popular hiking spot among the “Nine sisters”.
Almost all Nine sisters peaks have rocks that are
tan on weathered faces. (Gddy, n.d.)
• Based on their composition, I believe, these rocks
might be Dacite. Dacite has a composition
between Andesite and Rhyolite; therefore, they
are Light to dark gray on fresh faces; grayish, tan,
or orange on weathered faces.
• Boulders are usually round. It is said that about
20 to 25 million years ago, magma welled up
underneath a layer of softer rock and solidified.
The softer overlying rock has since eroded away,
leaving a distinct rugged shape. (Bishop Peak
Natual Preserve, n.d.)
Picture of Bishop Peak
hiking trail:
by: Neha J Pande

10. Principles of relative dating applied to Montana de Oro rocks
• Individual rock layer is seen exposed in the walls of
Montana de Oro state park, depicting that when the
layers were deposited, the strata must be mostly
horizontal (principle of original horizontality).
• The layers of the rock at the base were deposited first
and are therefore older than the rock exposed at the top,
showing the principle of superposition.
• On a closer look at the rocks, we can see that due to
tectonic forces, there must have been titling and folding
of the beds. There are cuts across the layers after the
rocks were tilted, showing the principle of cross-cutting
relationships.
• There are marine terraces (A wave-cut platform now
above sea level). The marine terraces are much younger
than the underlying strata. It looks like an angular
unconformity where erosional surface on tilted or folded
strata over which younger strata were deposited. The
strata below the unconformable surface do show a dip
steeper than those above, producing an angular
relationship. (Monroe & Wicander, 2009)
Marine
terraces at
Montana De
Oro State
park
Pictures of Montana De Oro :
by: Neha J Pande

11. Fauna of San Luis obispo  San Luis obispo showcases a variety of wildlife.
Along the shore: gray whales, blue whales and
humpback whales could be seen throughout the
year in addition to the dolphins, sea otters, sea
lions, and massive elephant seals could be seen.
 Over 200 species of birds are found in SLO
including Pelicans, herons, egrets, peregrine
falcons, bald eagles etc.
 In inland regions, coyotes, tule elk, mountain
rabbits, deer are common.
 Foxes, coyotes, bobcats and mountain lions,
gopher snakes and rattle snakes have also been
occasionally seen.
 At night, raccoons and opossums can be often seen
around the base of the mountains or moving into
urban areas from the cover provided by the dense
brush of the mountains. (Wildlife in SLO CAL |
Whale Watching, Bird Watching & Zoos, n.d.)
Pictures of Elephant
seals and Gopher snake
by: Neha J Pande

12. Evolution of elephant seal
• The northern elephant seal (Mirounga angustirostris) and the
southern elephant seal (M. leonina) are the largest pinnipeds.
• They are carnivorous and belong to the family of Phocidae.
• The north and the south species came from a common ancestor
about as little as 10,000 years ago to as far back as the
Pleistocene.
• San Luis Obispo county has Northern elephant seals.
• Northern elephant seals have been utilized for food and oil over
the centuries by native peoples of North America, leading to
colonies of seals depleting until 1850.
• But now, elimination of commercial harvest has allowed
northern elephant seals to recover fully from near extinction
despite a striking loss of genetic diversity. (Hindell & Perrin,
2009)
Picture by: Neha J
Pande

13. • San Luis Obispo boasts an impressive diversity
of plants, with more than 1,300 different native
species and countless other introduced weeds
and horticultural plants. (Ritter, n.d.)
• It is famous for its oak trees including coast live
oak, valley oak, blue oak, Fremont cottonwood,
and arroyo willow. (Hamma, 2021)
• Flowers include California Poppy, Chaparral
Yucca, Chocolate Lily and many others (Hamma,
2021)
Plants of San Luis Obispo, their
lives and story
Picture by: Neha J Pande

14.  California poppy Is the official state flower of California.
 The botanical name Eschscholzia honors a German
surgeon and naturalist Friedrich Gustav von Eschscholtz,
who saw the San Francisco Bay area hills covered with
California Poppy while on a Russian expedition ship in
the early 19th century. (California Poppy, n.d.)
 It is commonly seen blooming in the spring and summer
along country roads and freeways throughout California.
 The Native American peoples used California poppy for
toothaches, headaches and stomach aches, and as a
sleep aid for children. The Poppy extract is currently
used as mild sedative and analgesic, and an anxiolytic
(anti-anxiety remedy).
 Being a drought-resistant flower, the California Poppy
has adapted well to the California climate growing
successfully everywhere in the state. (Katz & Kaminski,
n.d.)
Evolution of Local
Flora: California poppy
Photo:
https://findersfree.com/science-nature/illegal-
pick-california-poppy

15. References:
• California Poppy. (n.d.). Retrieved August 14, 2022, from https://wildlife.ca.gov/Conservation/Plants/California-
Poppy
• Gddy, M. (n.d.). Nine Sisters. Retrieved August 14, 2022, from http://itstheslolife.weebly.com/nine-sisters.html
• Hamma, C. (2021, January 22). San Luis Obispo County’s Stealth Trees—Our Native Conifers. Morro Bay National
Estuary Program. https://www.mbnep.org/2021/01/22/san-luis-obispo-countys-stealth-trees-our-native-conifers/
• Helmenstine, A. M. (2020, August 2). What’s the Difference Between Shale and Slate Rock? ThoughtCo.
https://www.thoughtco.com/shale-rock-4165848
• Hindell, M. A., & Perrin, W. F. (2009). Elephant Seals: Mirounga angustirostris and M. leonina. In W. F. Perrin, B.
Würsig, & J. G. M. Thewissen (Eds.), Encyclopedia of Marine Mammals (Second Edition) (pp. 364–368). Academic
Press. https://doi.org/10.1016/B978-0-12-373553-9.00088-2
• Katz, R., & Kaminski, P. (n.d.). California Poppy: True Gold is in the Heart. Retrieved August 14, 2022, from
http://www.flowersociety.org/california-poppy.html
• Monroe, J. S., & Wicander, R. (2009). The changing earth: Exploring geology and evolution (5th Edition). Cengage
Learning.
• Problogic. (2017, October 26). The nine volcanic sisters of San Luis Obispo. Panethos.
https://panethos.wordpress.com/2017/10/26/the-nine-volcanic-sisters-of-san-luis-obispo/
• Ritter, M. (n.d.). Plants of San Luis Obispo [Text]. Plant Conservatory. Retrieved August 14, 2022, from
https://plantconservatory.calpoly.edu/plants-san-luis-obispo
• Serpentine: California’s State Rock. (n.d.). Retrieved August 14, 2022, from
https://www.conservation.ca.gov/cgs/Pages/Publications/Note_14.aspx
• The City and County of San Luis Obispo Present...Bishop Peak Natual Preserve. (n.d.). Bishop Peak Natual Preserve.
Retrieved August 14, 2022, from https://www.hikespeak.com/pdf/bishop-peak-natural-reserve.pdf
• Wildlife in SLO CAL | Whale Watching, Bird Watching & Zoos. (n.d.). Retrieved August 14, 2022, from
https://www.slocal.com/things-to-do/outdoor-activities/animals-wildlife/