Geology lab field

1. Southern California
Cuyamaca Mountains
Geology 103 – Spring 2018
Professor Lawler
Presented by Alexandra Coffi

2. Agenda
 Introduction
 Geological Background
 Cuyamaca Plants
 Cuyamaca Animals
 Cuyamaca Rocks
 Steno's Laws and Principles
 Unconformity
 References

3. Introduction
The geological history of a given area is a very difficult task to accomplish.
Knowing at some point of time when, how and why geological events
happened during the past, is extremely important in order to not only
understand but also predict future events. In fact, the this lab field
assignment will discuss several geological aspects related to a particular area
of the Southern California States. So, throughout this assignment, the
Cuyamaca Mountains will be the major area of the geological study.

4. Geological Background
History
 Cuyamaca Mountains are mountains contained in the
Peninsular ranges system in San Diego, Southern CA.
 Cuyamaca separate coastal and inland San Diego from the
desert.
 Rocks in this area are dominated by the Mesozoic granitic
rocks from a large igneous intrusive.
 During that specific period, extensive volcanic-arc system
began to develop along the western margin of the North
American continent.(USGS, 2010)
 Terrestrial and marine sedimentary deposits that inter-
fingered volcanic deposits from the volcanic centers lead
to the creation of Mountains. Cuyamaca Mountains Photo (Wiki)

5. Geological Background
History Continued
 This picture is the highest Cuyamaca
Mountains also know as the Cuyamaca
Peak.
 Rocks mostly found in this area are
igneous rocks mainly plutonic and granitic
 Elevation ~ 6,512 feet
 Geographical Coordinate
32° 56′ 31.18″ N, 116° 36′ 14.07″ W
Cuyamaca Mountains Photo (Wiki)

6. Geological Background
Evolution
 Around 165 million years ago, during the Jurassic Period of the Mesozoic Era, the west
coast of North America was being subjected to intense volcanic activity.(Geological GEMS
OF CA. State Parks, 2006)
 Further volcanism occurred later in two pulses during the Cretaceous period, which
possibly consisted of volcanic islands being formed offshore.(Geological GEMS OF CA.
State Parks, 2006)
 As the plate collision occurred, constant compression and squeezing happened in existing
igneous and sedimentary rocks causing them to metamorphose.(Geological GEMS OF CA.
State Parks, 2006)

7. Geological Background
Evolution Continued
 This active compression caused them to be pushed up and create huge mountains.
 Those two pictures below show us how the mountains evolve over time.
A series of granitic and metamorphosed sedimentary rocks that
represent past mountain building events. (Geological GEMS OF CA.
State Parks, 2006)
Cuyamaca mountains events today. (Geological GEMS OF CA. State
Parks, 2006)

8. Cuyamaca Plants
Chamise History
 Chamise or Greasewood, a member of
the Rose family, is a flowering plant
native to Southern California. (California
Native Plants Society, 2010)
 Chamise cover about 7,300,000 acres in
California.(Biology Science Santa Barbara
College, 2008).
 Scientific name is Adenostoma
fasciculatum. (California Native Plants
Society, 2010)
Chamise Pic. Taken at Cuyamaca Site

9. Cuyamaca Plants
Chamise History Continued
 The flowers turn rusty brown as they dry up and
remain on the plant for most of the
summer.(Biology Science Santa Barbara College,
2008).
 Four to twelve centimeter clusters of small, white
flowers appear from February to July, giving
chamise plants a whitish appearance. (Biology
Science Santa Barbara College, 2008).
Chamise Pic. Taken at Cuyamaca Site

10. Cuyamaca Plants
Chamise Evolution
 Chamise grows primarily in dry, hot areas, as such
the plants have a number of moisture saving
adaptations that are most easily seen in their leaves.
 Chamise is not generally considered to be good
browse for animals, but it is common to find
extensive patches of heavily browsed
plants. (Writing for Nature, 2012)
 It grows with little water, on hard, rocky soil, and can
even grow in serpentine soils, a soil type that kills
many plants. (Writing for Nature, 2012)
 Root systems of chamise are strong and extensive in
proportion to its top size, often exceeding 10 feet .
There is a tap root, but it is not dominant.
Chamise Pic. Taken at Cuyamaca Site

11. Cuyamaca Plants
Lemonade Berry History
 Lemonade Berry is a shrub or small tree, with
a variable form. (California Native Plants
Society, 2010).
 It is native to Southwestern and Pacific coastal
California from San Diego County.
 The scientific name is Rhus integrifolia and
There is a small inland population on Mount
Palomar at over 1000 meters.
 Flowers are small, radially symmetrical, about
¼ inch (6 mm) across and white to pink in
color. Flowers are born in terminal clusters
which appear Dec-May. (San Elijo Lagoon,
2008)
Lemonade Berry Pic. Taken at Cuyamaca Site

12. Cuyamaca Plants
Lemonade Berry Evolution
 The lemonade berry plant is found on dry slopes in
coastal areas of southern California and especially
northern Baja California.
 Specimens, seeds and drawings of new world plants
were taken to Europe by early explorers over many
years, and among those, the Lemonade Berry.
 By comparing fossil records with modern plants,
researchers could confirm their theories as to which
plants are native to California.
 Lemonade Berry have evolved over the years. They
provide essential environmental tasks, such as
manufacturing oxygen and filtering impurities from
our water.( CA. Dept. of Parks and Recreation, 2006)
 Lemonade Berry are plants that existed
in California prior to the arrival of European explorers
and colonists in the late 18th century.
Lemonade Berry Pic. Taken at Cuyamaca Site

13. Cuyamaca Animals
California Quail History
 The California quail (Callipepla Californica),
also known as the California valley
quail or valley quail, is a small ground-
dwelling bird.(Wiki, 2008)
 This bird, is a 9-11 inch hen-like bird with a
distinctive teardrop-shaped head plume
called a top-knot. ( San Francisco State Dept.
of Geography, 2008)
 California Quail are pretty as well as popular
with game hunters. They’ve been introduced
to many other parts of the world, including
Hawaii, Europe, and New Zealand. (Birds
Festivals, 2012)
Picture taken from Wiki

14. Cuyamaca Animals
California Quail History Continued
 Females have a smaller top-knot and lack the
male’s distinctive facial markings and black
throat.
 California quail are best adapted to semiarid
environments, ranging from sea level to 4000
feet and occasionally up to 8500 feet or higher
(Sumner 1935). (San Francisco State Dept. of
Geography, 2008)
 They can fly rapidly, but only for short
distances. When alarmed they prefer to run,
flying only as a last resort. (San Francisco State
Dept. of Geography, 2008)
Male California quail in the Presidio, San Francisco

15. Cuyamaca Animals
California Quail Evolution
 California quail are part of a group of quail
found only in the Americas called the New
World quails.
 Species appeared about 1–2 million years ago,
during the Late Pliocene or
Early Pleistocene.(Wiki, 2009)
 They are short lived with high mortality and
high reproductive rates.
 The number of quail in a population is
constantly undergoing change and the average
rate of mortality is 74 percent. Mortality is
highest in the first year of life. (San Francisco
State Dept. of Geography, 2008)
Picture taken from Wiki

16. Cuyamaca Animals
California ground squirrel
history
 The California ground
squirrel (Otospermophilus beecheyi), is a
common and easily observed ground
squirrel of Southern California.
 They may live as long as six years, but
three or four years is probably their
average life span in the wild. (California
Ground Squirrels, 2006)
 They can be found in open areas including
fields, pastures and lightly wooded areas.
(Nature Works, 2010) Pic. Taken at Cuyamaca Site

17. Cuyamaca Animals
California ground squirrel Evolution.
 Between 10 and 14 million years ago, a relatively
rapid diversification gave rise to lineages leading
to marmots and to several distinct groups of
ground squirrels.
 Record of the ground squirrel appears about 35
millions years ago.
 Thorington et al. (2012) proposed 2 hypotheses
concerning the possible ancestors of
Otospermophilus: 1) Miospermophilus (late
Oligocene to middle Miocene, about 24–12
million years ago) and 2) Spermophilus (middle
Miocene, 16 million years ago in North America).
 Otospermophilus occurred as early as the
beginning of late Miocene. (Mammalian
Species, 2010) Pic. Taken at Cuyamaca Site

18. Rocks of Cuyamaca Mtn.
Igneous Rock (Rhyolite)
 When I first took a look on this rock, it was very fine
grained with a pinkish-grey color.
 It also had some dark streaks and tear a paper rather
than leave a muddy streak when I was trying to rub it in
a piece of paper, it is very likely to be a rhyolite
(extrusive.)
 Rhyolite is formed by magma that has reached the
Earth’s surface (lava) and therefore cools very quickly.
Lava can explode out of a volcano and make pumice or
ash, or flow down its side and make thick layers of fine
grained rock or volcanic glass. (Mining Matters, 2004) Pic. Taken at San Diego

19. Rocks of Cuyamaca Mtn.
Metamorphic Rock (Quartzite)
 I think this rock is a non-foliated quartzite because I could
see interlocking quartz crystals with the naked eye.
 It rock was very hard and had a medium grain size
distribution. In addition to that, it was generally gritty to
touch.
 Quartzite generally comprises greater than 90% percent
quartz, and some examples, containing up to 99% quartz, and
are the largest and purest concentrations of silica in the
Earth's crust.(Geology Rock & Minerals, 2000)
 Quartzite forms at very high temperatures and pressures.
 Also, this rock shows that the protolith was probably a clean
quartz sandstone and the orange coloration was probably a
precipitated from percolating ground water along fracture-
surface.
Pic. Taken at San Diego

20. Rocks of Cuyamaca Mtn.
Igneous Rock (Granite)
 I think this rock a a granite (intrusive rock) because I could
see through the rock both felsic silicate quartz (clear) and
alkali feldspars (white) minerals. It was kind of hard to tell,
but I was 100 percent sure I was right.
 Also, visible white and black crystal were on the rock.
 There was no sign of horizontal banding in the rock.
 Biotite mica, a dark, slightly mafic silicate was present in
this rock.
 Granite is formed by magma that cools very slowly into
hard rock below or within the Earth’s crust.(Mining Matters,
2004)
Pic. Taken at San Diego

21. Steno's Laws and Principles
Law of Superposition
 By assuming that all rock layers were originally
horizontal, we can make another assumption: that
the oldest rock layers are furthest toward the
bottom, and the youngest rock layers are closest to
the top.
 This is important to stratigraphic dating, which
assumes that the law of superposition holds true
and that an object cannot be older than the
materials of which it is composed.(Wiki)
 The law was first proposed in the late 17th
century by the Danish scientist Nicolas Steno. (Wiki,
2010)
 On the picture to the right, based on the
superposition law, the oldest is the very bottom rock
(granite). And as we are going upward, the rocks
becomes youngers.
 In our case, the younger one might be a rhyolite. Pic. Taken at Cuyamaca Site
rhyolite
Granite

22. Unconformities
An unconformity is a buried erosional or non-
depositional surface separating two rock masses
or strata of different ages, indicating
that sediment deposition was not continuous. (Wiki)
Angular Unconformity
 An angular unconformity is an unconformity where
horizontally parallel strata of sedimentary rock are
deposited on tilted and eroded layers, producing an
angular discordance with the overlying horizontal
layers.
 As you can see on the picture, we noticed that a
sedimentary rock was forming at some point of
time.
 Then, a geological event happened to that rock
(might be erosion due to water or wind), and new
deposition starts at the top of the eroded rock.
Pic. Taken from wiki
Pic. Taken at San Diego
New
Deposition
Erosion Happened
here
Sedimentary rock

23. References
 Western Region Geology and Geophysics Science Center. (2006, July 26).
Retrieved June 21, 2018, from
https://geomaps.wr.usgs.gov/archive/socal/geology/geologic_history/index.html
 Andrei, M. (2017, March 28). Geology ABC -- How to identify granites. Retrieved
July 21, 2018, from https://www.zmescience.com/science/geology/how-to-
identify-granites/
 School Programs - Students. (2004). Retrieved July 21, 2018, from
http://miningmatters.ca/school-programs/students/rock-and-mineral-
identification-guides/rock-identification-guide
 Unconformities. (2010). Retrieved July 21, 2018, from
http://www.indiana.edu/~geol105b/images/gaia_chapter_6/unconformities.htm
 California Ground Squirrels. (2006). Retrieved June 21, 2018, from
http://www.mary.cc/squirrels/cgs.htm

24. References
 Lemonade Sumac, Rhus integrifolia. (2010). Retrieved June 21, 2018, from
http://calscape.org/Rhus-integrifolia-(Lemonade-Sumac)
 Cuyamaca Rancho State Park. (2013). Retrieved July 21, 208, from
https://www.inaturalist.org/check_lists/5673-Cuyamaca-Rancho-State-Park-Check-
List?iconic_taxon=40151
 Cuyamaca Mountains. (2016, April 01). Retrieved June 21, 2018, from
https://www.fodors.com/world/north-america/usa/california/north-county-and-
around/places/cuyamaca-mountains
 J. McIlvaine, & SFSU. (2000). Biogeography of California quail (Callipepla californica).
Retrieved July 23, 2018, from
http://online.sfsu.edu/bholzman/courses/Fall00Projects/Quail.html