The Monterey Bay was formed between 16-6 million years ago during the Miocene Era. Coastal upwelling caused diatoms to collect on the sea floor, forming silica shells that later turned to oil and gas. The Monterey Formation spans 1,750 square miles of central and southern California and contains about two-thirds of the nation's petroleum reserves. Key plants native to the Monterey Bay area include the endangered Sand Gilia, which grows in coastal dunes, and the Cypress tree, which has adapted to require minimal soil. Endangered animal species such as the California Condor, North America's largest flying bird, are also found in the region.

1. Monterey Bay
By Heather Anderson
Lake Tahoe Community College
Geology 103 Mr. Lawler

2. Monterey Formation• The Monterey Bay was formed during the
Miocene Era in between 16 and 6 million years
ago during a period where the Earth was
cooling down (The Mighty Monterey
Formation, 2012)
• Coastal upwelling happened all around the
California coast due to the great current system
reorganizing itself.
• Diatoms, a single celled algae, collected on the
bottom of the sea. Their silica-shelled bodies
were preserved on the zero oxygen sea bed
turning them into petroleum, oil and gas. (The
Mighty Monterey Formation, 2012)
• At the same time, their shells turned into
quartz.
• The rocks changed from Diatomite to
porcellanite and later into chert. As the rock
changed, room was given for the oil to move
around.
• The San Andreas fault system bent the rock
into domes and folds creating reservoirs for the
oil. (Monterey Shale, 2013)

3. Fossils from Monterey Formation, found on Rio Del Mar beach in Aptos,
California on April 25th 2016.
Sea shell fossil (possibly barnacle)
Sedimentary rock

4. Monterey Bay Shale Formation
The Monterey Formation has about two-
thirds of the nations petroleum.
Tectonic activity compressed the siliceous
rocks and piled them up along the California
coast causing them to release their oil into
overlying rocks.
The Monterey Formation spans over
1,750 square miles of central and
southern California.
Monterey Shale Shakes Up California's Energy Future. (n.d.). Retrieved June 18, 2016, from
http://news.nationalgeographic.com/news/energy/2013/05/130528-monterey-shale-california-fracking/

5. Metamorphic rocks like the graphitic marble
that occur as intrusions in the granite formed
during the Cretaceous period.
Granitic rocks intrude these
metasedimentary rocks, their age is
uncertain but is probably
Mesozoic or Paleozoic (Mighty Monterey,
2012).
The hornblende-biotite tonalite contain
dark diorite inclusions in the basement
of Tomales Point. It is Lithologically
similar to the tonalite that can found 20
miles north at the Bodega Head, and is
considered to be from the same granitic
mass dating 94 million years ago
(Mighty Monterey, 2012).
The very thick arkosic sandstone
beds and sandy conglomerate
beds consist of up to 50% of
subangular porphyritic
granodiorite clasts up to 3 miles
long (Monterey Shale, 2013)

6. Monterey Bay Shale Formation
The nonconformities found in the
Monterey Formation are made up
of deformed Tertiary marine
sedimentary rocks that consist of
three sequences:
1.) Conglomerate of Galloway
2.) Basal sandstone known as the
Laird Sandstone
3.) The overlaying porcelanite unit
known as the Monterey Formation
Resting unconformably on all of this
are transgressive beds of the
Miocene and Pliocene sequence
that include basal glauconitic
sandstone, siltstone, and mudstone
(Mighty Monterey, 2012).
This image shows that the Principle of Superposition exists, the layers
of sedimentary rock on the bottom are much older than the rock layers
on top.

7. Monterey Bay Plant Life
• Gilia tenuiflora ssp. Arenaria The Gilia Tenuiflora better known as the
Sand Gilia, grows in the coastal dunes in
the Monterey Bay area.
The Sand Gilia blooms in April thru June
and only germinates in the sandy dunes
where it can be sheltered from the wind by
shrubs or small hills.
Failed attempts of replanting Sand Gilias in
other areas leave this plant endangered
(Abrams, 1951).

8. Cypress Tree (hesperocyparis macrocarpa)
• The Cypress tree is native to the
central coast area
• Requires bare minimum soil for
germination
• Seedlings are sensitive to moisture
• Radiative speciation widely occurred
in gymnosperms in the middle to late
Cenozoic.
• Many coniferous genera originated in
North America and migrated into
Eurasia.
• The earliest conifers date to the late
Carboniferous period 300 million
years ago
• Important adaptation of the
gymnosperms was to not be so
dependent on water sources
• They were the dominant land plants
of the Mesozoic period
• Another adaption are pollen and the
seed which travel with wind to
develop in other areas.
Cupressus macrocarpa. (n.d.). Retrieved June 19, 2016, from
http://www.fs.fed.us/database/feis/plants/tree/hesmac/all.ht
ml

9. California Condor
• The California Condor is the largest flying
land bird in North America weighing up to
20 pounds and a wingspan up to 3 meters
wide
• Currently the condor is endangered
• They are scavengers and only eat animals
that are already dead
• They only lay one egg every other year
• The condor history and human history are
linked to have originated around the same
time
• Fossil records date back to 100, 000 million
years ago to the Middle Pleistocene Epoch
California Condors, California Condor Pictures, California
Condor Facts - National Geographic. (n.d.). Retrieved June 19,
2016, from
http://animals.nationalgeographic.com/animals/birds/californi
a-condor/

10. References
• Abrams, L. R. 1951. Illustrated Flora of the Pacific States, Vol. 3. Stanford University Press, Palo
Alto, CA.
• The Mighty Monterey Formation: In Your Future. (n.d.). Retrieved June 18, 2016, from
http://ww2.kqed.org/quest/2012/11/29/the-mighty-monterey-formation-in-your-future/
• Monterey Shale Shakes Up California's Energy Future. (n.d.). Retrieved June 18, 2016, from
http://news.nationalgeographic.com/news/energy/2013/05/130528-monterey-shale-california-
fracking/
• California Condors, California Condor Pictures, California Condor Facts - National Geographic.
(n.d.). Retrieved June 19, 2016, from
http://animals.nationalgeographic.com/animals/birds/california-condor/
• Monroe, J. S., & Wicander, R. (2009). The changing Earth: Exploring geology and evolution.
Belmont, CA: Brooks/Cole, Cengage Learning.
• Cupressus macrocarpa. (n.d.). Retrieved June 19, 2016, from
http://www.fs.fed.us/database/feis/plants/tree/hesmac/all.html