Download Pacific Beach San Diego

The Geologic Diversity of Southern California
By Michael Nauss
Geology 100 Photo Essay
Professor Farquharson
5/5/2017
Table of Contents
California Regional Map................................................................................................................. 4
Introduction ..................................................................................................................................... 5
Pacific Beach San Diego ................................................................................................................. 7
Pacific Beach Terraces ............................................................................................................ 8
Gypsum Strata ......................................................................................................................... 9
Conglomerates of Pacific Beach ........................................................................................... 10
Folded Sedimentation ........................................................................................................... 11
Tourmaline Beach Cliffs ....................................................................................................... 12
Pala California .............................................................................................................................. 13
Mine Entrance #1 .................................................................................................................. 14
Pegmatite Laccolith .............................................................................................................. 15
Gemstones of Oceanview Mine ............................................................................................ 16
In-Ko-Pah Mountains.................................................................................................................... 17
Granite Boulders ................................................................................................................... 18
Metamorphic Boulder ........................................................................................................... 19
Round Mountain ................................................................................................................... 20
Carrizo Badlands ........................................................................................................................... 21
Elsinore Fault ........................................................................................................................ 22
Folded Olla Formation .......................................................................................................... 23
Angular Unconformity .......................................................................................................... 24
Basaltic Intrusion .................................................................................................................. 25
Canyon View ........................................................................................................................ 26
Coyote Mountains ......................................................................................................................... 27
Sand and Gravel Mine .......................................................................................................... 28
Eroded Sedimentary ridge..................................................................................................... 29
Sedimentary Bedding ............................................................................................................ 30
Bioclastic Sedimentary Rock ................................................................................................ 31
Eroded/Weathered Sandstone ............................................................................................... 32
Salton Sea...................................................................................................................................... 33
Salton Sea.............................................................................................................................. 34
Obsidian Boulders ................................................................................................................. 35
Salt Beds ............................................................................................................................... 36
Cargo Muchacho Mountains ......................................................................................................... 37
American Girl Kyanite Mine ................................................................................................ 38
Tumco Mine Area ................................................................................................................. 39
Tumco Mine Area ................................................................................................................. 40
Sandstone Creation ............................................................................................................... 41
Metamorphic Mountain ........................................................................................................ 42
Beautiful Sunset .................................................................................................................... 43
Appendix ................................................................................................................................... 44
Glossary of Terms ................................................................................................................. 44
Glossary of Terms ................................................................................................................. 45
2
Glossary of Terms ................................................................................................................. 46
Glossary of Terms ................................................................................................................. 47
Geologic Time Scale ............................................................................................................. 48
Geologic Time Scale of Southern California ........................................................................ 49
Photo Gallery of Minerals ..................................................................................................... 50
Bibliography ......................................................................................................................... 53
Bibliography ......................................................................................................................... 54
Bibliography ......................................................................................................................... 55
Bibliography ......................................................................................................................... 56
3
California Regional Map
Copyright [2006] by Andrew Alden, geology.about.com, reproduced under educational fair use.
4
Introduction
During the last 150 million years, Southern California has undergone vast geological land
sculpturing. Volcanoes, earthquakes, landslides, weathering, and tectonic movement have all
contributed to the present day face of Southern California. This paper will visit a few of the
geologic timestamps that are beautifully carved into the coastal and desert regions of Southern
California.
The early times of the Cretaceous period, 150 to 65 million years ago were turbulent
times for southern California, as the Farallon plate was subducting underneath the North
American plate, and volcanoes scorched the California interior. This was a period of mountain
building and land reshaping. Much of present day California was submerged in the Pacific,
teaming with crustaceans, and invertebrates which would eventually help form the bioclastic
portions of the coastal sedimentary beds. Some 75 million years ago, San Diego was submerged
in the ocean; heavy tides swept the sandy floor throughout the region depositing beds of sand
that would later become a time marker for the sedimentary bedrock. As the ocean waters began
to subside, and reveal the ever now so popular San Diego coastline, the once coastal ocean
community of marine animals laid rest a final chapter in the coastal diary. (Abbott, 1999)
Further inland near the Colorado River, erosional sedimentation was sealing the fate for
the Gulf of California as the ever increasing flow of fine grained soil was being deposited, and
would begin to separate the Salton Trough from its oceanic cousin, the Gulf of California. The
deposition left by the flowing waters of the Colorado River partitioned the Gulf of California
from the current San Diego/Imperial desert regions. In the wake of this regional segregation, are
fossilized records dating back to the Miocene age. This is very fortunate for geologist, as this
5
assemblage of fauna provides a great deal of information about San Diego’s geological past in
terms of the biosphere, hydrosphere, and lithosphere.
Though the oceans, and the Colorado River played a key role in Southern California’s
land shaping, heavy rains, and flooding have also contributed to large canyons, valleys, and
troughs throughout the region. Considerable mass wasting has formed the alluvial fans found
throughout the Imperial valleys. Much of the desert plains are a result of massive flooding
removing tons of debris in its path.
In harmony with these processes were volcanoes, further contributing to the mountain
building of the peninsular ranges, and the desert rim. Lava flows are evident throughout these
areas, and a perfect example can be seen in the Carrizo Badlands. (Remeika & Lindsay, 1992)
Join with me now as we venture from the marvelously sculpted terraces of the San Diego
coastline to the alluvial canyons of the Salton Trough, and deserts, where we will travel back into
geological time, and picture a once thriving community of marine life and terrestrial creatures.
6
Pacific Beach San Diego
Topographical map of Pacific Beach San Diego, California.
7
Pacific Beach San Diego
Name:
Pacific Beach Terraces
10/19/2006
Date:
Location: Tourmaline Beach San Diego California
Located in one of San Diego’s most lively hotspots of Pacific Beach lies a spectacular
testament to San Diego’s geologic history, just south of La Jolla California is Tourmaline Beach.
As your descending the stairs from the beach parking lot, your eyes are treated to 65 million
years of history.
The exposed cliffs of Tourmaline state beach are like an open book revealing the geologic
history of San Diego’s coastal past. The sedimentary layers represent periods of deposition, and
unconformities which provide a recorded transcript of millions of years past.
8
Pacific Beach San Diego
Name:
Gypsum Strata
10/19/2006
Date:
Location: Tourmaline Beach San Diego California
Embedded into the sandstone rock is a stratum of gypsum rock. Gypsum (satin spar) is
know as an evaporite, which occurs when sodium and carbonates are mixed in a hydrated
solution, and evaporates from within a sedimentary rock. As this gypsum layer was some seven
feet above the basement layer, one can conclude that the level of the ocean surface was once
higher than present day. These shifts in the ocean levels can be attributed to glacial melt and
freeze cycles.
9
Pacific Beach San Diego
Name:
Conglomerates of Pacific Beach
10/19/2006
Date:
Location: Tourmaline Beach San Diego California
The well lithified sandstone is a much older representative of this formation. This is
evident as the conglomerate material that scours the sandstone separates the orange banding of
the sandstone. Weathering and tides allowed the intrusion over time.
10
Pacific Beach San Diego
Name:
Folded Sedimentation
10/19/2006
Date:
Location: Tourmaline Beach San Diego California
This is one big mud sandwich, created very long ago. Some time in the distant past
massive movement of earth slid along the cliff sides, sheets of mud were overlain upon each
other where gravity and weight folded the mass near the basement edge. Further mud sheets
were laid above, and lithified leaving this peculiar pattern of a once stormy event.
11
Pacific Beach San Diego
Name:
Tourmaline Beach Cliffs
10/19/2006
Date:
Location: Tourmaline Beach San Diego California
The basement conglomerate rock of this formation is from the Cretaceous Cabrillo
Formation some 72 million years ago. Above the conglomerate strata are rocks of the Eocene
epoch and above that are the rocks of the Pliocene epoch. An unconformity exists between these
two layers, and represents a loss of some 43 million years. One should ponder, what caused such
a large gap in time? (Abbott 1999)
12
Pala California
Topographical map of Pala California.
13
Pala California
Name:
Mine Entrance #1
9/10/2006
Date:
Location: Oceanview Mine Pala California
Just off of I-76 in Northeast San Diego County is the Pala Oceanview Mine, one of the
largest tourmaline producing mines in the United States. Tourmaline, a highly sought after
mineral by collectors, for its beauty and rarity, are only found in sparse locations throughout the
world. Few tourmaline mines exist in the world, thus the gem mines of Pala afford San Diegan’s
with a special treat.
Tourmaline crystals are found in pegmatite rocks. Pegmatites are igneous rock
formations that are usually found as dikes and sills. Erosion exposes the pegmatite, and is
referred to as an outcrop. As to not damage valuable gem crystals, care must be taken when
mining the pegmatite. Explosive pipes are used in such a way as to break large pockets of
pegmatite, but pick and shovel is the main tools of use. This is a slow and tedious process, but
the unearthing of spectacular gem crystals is the reward. In addition to the tourmaline, many
other minerals are found, such as: kunzite, morganite, aquamarine, and beryl. (Swanger 2006)
14
Pala California
Name:
Pegmatite Laccolith
9/10/2006
Date:
Location: Oceanview mine Pala California
Laccoliths are formed when concordant plutons, low viscous magma intrudes between
sedimentary layers. The laccoliths are not exposed until sufficient weathering and erosion takes
place. This pegmatite laccolith is rich in plagioclase, muscovite, and quartz. Other minerals in
trace amounts include lepidolite, tourmaline, kunzite, and beryl. (Tarbuck & Lutgens, 2005)
15
Gemstones of Pala California
Name:
Gemstones of Oceanview Mine
9/10/2006
Date:
Location: Oceanview mine Pala California
The gemstones pictured above were found at the Oceanview mine. The principle
minerals that are mined at Oceanview are tourmaline, (shown at middle and upper right) aquamarine,
a variety of beryl, (upper left) and kunzite (bottom). Although not considered a gemstone, quartz,
lepidolite, and muscovite are also present in the pegmatite rocks.
16
In-Ko-Pah Mountains
Topographical map of In-Ko-Pah Mountains.
17
In-Ko-Pah Mountains
Name:
Granite Boulders
9/17/2006
Date:
Location: In-Ko-Pah Mountains
Just off of Interstate 8 in the eastern San Diego County are the In-Ko-Pah Mountains.
Despite the appearance, these massive boulders were not placed here by large ugly trolls; in fact
they were not placed here by any creature at all. Sometime in the far distant past these igneous
rocks were part of a large batholith. The once buried batholith was exposed to the surface
through uplifting and erosion, a process which takes tens of millions of years. These granite
rocks and boulders are strewn throughout the In-Ko-Pah Mountains.
18
In-Ko-Pah Mountains
Name:
Metamorphic Boulder
9/17/2006
Date:
Location: In-Ko-Pah Mountains
Amidst all the igneous granite rocks, this metamorphic gneiss is somewhat a mystery as
to how it got there. One thought is that previous igneous rock was later surrounded by newer
magmatic intrusions which partially melted the rock to form this gneiss specimen. This
particular rock is over six feet in height; the crack was a result of hydrous fluid seeping into the
rock, where the fluid froze and pried the rock apart. Of course this boulder is not quite as gneiss
with the crack running through it.
19
In-Ko-Pah Mountains
Name:
Round Mountain
9/17/2006
Date:
Location: In-Ko-Pah Mountains
Arguments still continue over this geologic structure. The surrounding basaltic rock and
other igneous material hint of a cinder cone, but scientist need something to disagree on. This
formation, just west of a convenient gas station and fast food store are a stopping point for many
explorers of the In-Ko-Pah and Coyote mountains.
20
Carrizo Badlands
Topographical map of the Carrizo Badlands.
21
Carrizo Badlands
Name:
Elsinore Fault
10/27/2006
Date:
Location: Canyon Sin Nombre
One expects the ground to suddenly give way as they view this colorful canvas of Mother
Earth’s creation. Amidst the hues of lavenders and reds, lies a sleeping giant, the Elsinore fault.
“Last known activity of this fault was in 1910, registering an estimated 6 magnitude earthquake.”
Looking at the lower central part of this photograph are sills and dikes of intrusive igneous rock.
Further up the cliffs face, just above the pinkish color rock is limestone sedimentation.
(Wikipedia, 2006)
22
Carrizo Badlands
Name:
Folded Olla Formation
10/27/2006
Date:
Location: Canyon Sin Nombre
Geologist set to scale; Near the Elsinore strike slip fault, are these folded beds of
Pleistocene sedimentation. The Olla—Spanish, translated, pot—Formation is composed of lightgray to olive-gray sandstones, biotite rich siltstone, and dark olive siltstone and clay stones, and
is some two-hundred meters thick to zero meters where it contacts the Canebrake Formation and
the Arroyo Diablo formation. Besides the geologic importance of this formation, it looks cool.
(Cassiliano, 2002)
23
Carrizo Badlands
Name:
Angular Unconformity
10/27/2006
Date:
Location: Canyon Sin Nombre
Quoting a well renowned geologist, “This is a classic example of an angular
unconformity.” Located in the lower portion of Canyon Sin Nombre, this unconformity presents
a beautiful glimpse of an ever violent geologic history. (Farquharson, 2006)
24
Carrizo Badlands
Name:
Basaltic Intrusion
10/27/2006
Date:
Location: Canyon Sin Nombre
This incredibly bright shade of pastel purple is a basaltic andesite, an extrusive igneous
rock, formed by viscous lava flow. This lava formation dates back some 7 to 5 million years
ago, a relative youngster of this canyon formation. An unconformity rest above the basaltic unit
and is a relatively recent formation. (Bloom, 2006)
25
Carrizo Badlands
Name:
Canyon View
10/27/2006
Date:
Location: Canyon Sin Nombre
This majestic view of this alluvial fan is some 200 meters above the basin of Canyon Sin
Nombre. Overlooking the Carrizo Badlands, this canyon represents millions of years of erosion
and mass wasting. Throughout the cliffs are clays and mudstones, as well as volcanic intrusions
of basaltic rock. Those wishing to transverse this chasm from its basin can expect a 2 hour or
longer hike. The sparseness of shade gives little relief from the sun as you ascend this canyon,
but the eye candy presented to those willing to partake in this journey, makes the climb well
worth the blistered feet.
26
Coyote Mountains
Topographical map of the Coyote Mountains.
27
Coyote Mountains
Name:
Sand and Gravel Mine
9/16/2006
Date:
Location: Shell Canyon
North of Interstate 8 near the city of Ocotillo, is Shell Canyon. In this area, there are a
vast number of geological points of interest, from an array of geological formations, to strata of
fossil beds.
It is of little surprise that sand and gravel would be mined here. Beds of sand, and gravel
are abundant on the desert floor as wind; rain, flooding, and erosion have been hard at work.
This geologic resource is of significant value to the construction community. Near this site are
sand dunes, worthy of a few Megabytes of a digital cameras memory card.
28
Coyote Mountains
Name:
Eroded Sedimentary ridge
9/16/2006
Date:
Location: Shell Canyon
This picturesque image, from a geological perspective is a relatively young formation,
approximately 7 to 5 million years ago. This age approximation is based on fossils found
embedded in the substrate. Though deposition of the fossils could have occurred as a result of
erosional transportation, this is unlikely since much of the bioclastic material is well cemented
into sedimentation. The fossil pictured above is a partial test echinoderm (sea urchin) shell from
the late Miocene to early Pliocene age. (Deméré, 2006)
29
Coyote Mountains
Name:
Sedimentary Bedding
9/16/2006
Date:
Location: Shell Canyon
The white rock embedded within this sediment is a layer of gypsum, and it represents a
time when the ocean waters that once submerged this area were beginning to recede. Based on
known information about the receding waters, it is apparent as to the age of this rock section,
about 4 million years. Obviously the sedimentation below the gypsum strata is of older times.
(Remeika & Lindsay, 1992)
30
Coyote Mountains
Name:
Bioclastic Sedimentary Rock
9/16/2006
Date:
Location: Shell Canyon
Many people are amazed the first time that they see the fossilized remains of seashells
within the desert. These fossil remains represent several of the over sixty types of bivalvia shells
of the late Miocene Imperial group. Seen above are Pycnodonte heermani, a species of oyster,
Pectinidae, scallops species, and the Veneridae, Venus clam family. (Deméré, 2005)
31
Coyote Mountains
Name:
Eroded/Weathered Sandstone
9/16/2006
Date:
Location: Shell Canyon
Here is an example of mass wasting. Heavy rains and flooding have been hard at work
here eroding away at this mountain ridge. Notice the highly unsorted angular rock in the right
portion of this image. This is indicative of flooding that was able to carry large debris over a
short distance. The angularity of the rocks reveals that these cemented grains of sand have not
traveled far, and have not yet succumbed to the forces of weathering. The fine grained crust in
the left portion of this image is further evidence of heavy saturation of water in this area.
32
Salton Sea
Topographical map of Obsidian Butte.
33
Salton Sea
Name:
Salton Sea
8/27/2006
Date:
Location: Obsidian Butte
Although this looks like a scene from the aftermath of Chernobyl, it is part of the Salton
Sea near Obsidian butte. The white patches seen in the water are salt sediments. The salt is
transported to the sea by way of the Colorado River. Unfortunately the salt accumulates as water
evaporates. As new water replenishes the sea the salt remains, thus each year the salinity
increases. This poses an ecological problem that most likely won’t be solved.
The large structure in the background is part of a geothermal power plant. The plant is
one of many, and each one generates roughly 30 to 40 megawatts of electrical power for urban
use. The source of energy for these power plants is geothermal energy produced by volcanic
activity of Obsidian butte. (Salton Sea Authority, 2000)
34
Salton Sea
Name:
Obsidian Boulders
8/27/2006
Date:
Location: Obsidian Butte
Volcanic glass, or obsidian, technically, not considered a mineral as it has no crystal
lattice structure. This is due to rapid cooling of the highly silicate magma. The banding of the
rock is not sedimentary in nature, rather it is due to frothing of the magma as it was flowing and
cooled. This extrusive igneous rock is abundant in this region, in fact much of the trails, and
roads are atop obsidian bedrock.
35
Salton Sea
Name:
Salt Beds
8/27/2006
Date:
Location: Obsidian Butte
This odd looking surface resembles something that you would find on the surface of
Earth’s only orbiting satellite the moon, but it is actually a crust of evaporated salt water, and
alga rich mud. The salt (halite) transported to this area from the Colorado River is an
accumulation of many years of deposition and evaporation. (Salton Sea Authority, 2000)
36
Cargo Muchacho Mountains
Topographical map of the Cargo Muchacho Mountains.
37
Cargo Muchacho Mountains
Name:
American Girl Kyanite Mine
9/3/2006
Date:
Location: Cargo Muchacho Mountains
Near the Colorado River, The town of Ogilby, a once thriving mining community is host
city to a vast mining area the Cargo Muchacho Mountains. The mining in this area, though still
heavily marked with mine claim markers has mostly been abandoned.
An old feeder used for mining of kyanite, long since abandoned, as more profitable
kyanite mines were discovered in other parts of the country. Kyanite was the principal mineral
of interest here as it was a commodity for the ceramics industry. One use of the ceramics was in
the auto industry as insulative material for sparkplugs. The kyanite is abundant here, and is
easily recognized as its blue crystals contrast with the surrounding white metamorphic rocks.
38
Cargo Muchacho Mountains
Name:
Tumco Mine Area
9/3/2006
Date:
Location: Cargo Muchacho Mountains
This metamorphic schist is the victim of chemical and mechanical weathering. The
desert rains abundant with carbon dioxide (CO2) produces carbonic acid (H2CO3). This acid
breaks down the silicates in the schist into clays; much of which are transported in the direction
of gravity. Further weathering occurs as cold winter rains turn to ice, and cleave the platy
segments of the schist. This weathering contributes to the rock cycle as this metamorphic rock is
broken down into finer grains of detritus sediment, and sandstone. Just off of Ogilby road the
Tumco mine can be seen. This mine—now closed—was a goldmine. The cost to extract the ore
proved to be more than the value of the extracted ore, thus the mine has long since been
abandoned. (Locals, 2006)
39
Cargo Muchacho Mountains
Name:
Tumco Mine Area
9/3/2006
Date:
Location: Cargo Muchacho Mountains
Here it can be seen how weathering and erosion has contributed to the removal of
mountains. This deposition of fine grain sand is of silicate parentage, and some time in the
future will become part of a sedimentary rock bed, or perhaps even part of a metamorphic rock.
The ripples in the sand demonstrate transportation, and deposition, and the cracks in the sand are
evident of precipitation of water, and the lithification process.
40
Cargo Muchacho Mountains
Name:
Sandstone Creation
9/3/2006
Date:
Location: Cargo Muchacho Mountains
Not quite the Grand Canyon, yet this sandstone formation provides a glimpse of the rock
cycle hard at work cementing grains of sand into what may someday be a mountain. The
carvings of the stone, created by rain, and acidic concoctions can be seen throughout this
sedimentary bed. Imagine what this might look like over the next few million years, or will this
formation submit to the whims of wind and rain?
41
Cargo Muchacho Mountains
Name:
Metamorphic Mountain
9/3/2006
Date:
Location: Cargo Muchacho Mountains
A splendid example of Mother Nature’s work, the jagged peaks, and sandy cliffs reveal
the awesome sculpture created out of this rock. Luckily two mother play a role in this marvelous
monument to the California Deserts, and that is Mother Time, as this masterpiece took millennia
if not epochs to create. The sand along the cliffs transported from miles away, now lays
foundation for future renovations of this mountain side. Though weathering my change the face
of this awe inspiring sight, I have no doubt that the new creation epochs away will be equally
stunning for the eye to see.
42
The Sunset
Name:
Beautiful Sunset
10/9/2006
Date:
Location: Somewhere near the Hauser Geode Beds
The de rigeur sunset. Somewhere in the desert, lost during the shooting of this photograph, but
that’s a story for another time...
43
Appendix
Glossary of Terms

Alluvial pertaining to alluvium.

Alluvium “a deposit of sand, mud, etc., formed by flowing water. The sedimentary
matter deposited thus within recent times, esp. in the valleys of large rivers.”
(Dictionary.Com, 2006)

Andesite “is an igneous, volcanic rock, of intermediate composition, with aphanitic to
porphyritic texture. The mineral assembly typically is dominated by plagioclase plus
pyroxene and/or hornblende. Biotite and quartz and iron-titanium oxides are common
accessory minerals.” (Wikipedia, 2006)

Aquamarine a transparent, light-blue, or greenish-blue variety of beryl, used as a gem.
“Aquamarine is a beryl with a hexagonal crystal structure and a chemical formula of
Be3Al2Si6O18, a beryllium aluminium silicate mineral. It has a specific gravity of 2.68 to
2.74 and a Mohs hardness of from 7.5 to 8” (Wikipedia, 2006)

Basalt “is a common gray to black volcanic rock. It is usually fine-grained due to rapid
cooling of lava on the Earth's surface. It may be porphyritic containing larger crystals in a
fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or gray.” (Wikipedia,
2006)

Batholith “is a large emplacement of igneous intrusive (also called plutonic) rock that
forms from cooled magma deep in the Earth's crust.” (Wikipedia, 2006)

Beryl “is a beryllium aluminium cyclosilicate with the chemical formula Be3Al2(SiO3)6.
The hexagonal crystals of beryl may be very small or range to several meters in size.
Terminated crystals are relatively rare. Beryl exhibits conchoidal fracture, has a hardness
of 7.5-8, a specific gravity of 2.63-2.80. It has a vitreous luster and can be transparent or
translucent. Its cleavage is poor basal and its habit is dihexagonal bipyramidal.”
(Wikipedia, 2006)

Bioclastic sedimentary rocks consisting of biologic organisms. See Fossils

Biotite “is a common phyllosilicate mineral within the mica group, with the approximate
chemical formula K (Mg, Fe++)3AlSi3O10(F, OH)2.” (Wikipedia, 2006)

Cinder Cone “a cinder cone is a steep-sided volcanic peak with a large summit crater. It
is composed mainly of volcanic ash and rock spewed out of the vent during explosive
eruptions.” (Wikipedia, 2006)

Concordant Pluton “an intrusive igneous body with contacts parallel to layering or
foliation surfaces of rocks into which it has intruded.” (Leet, 1982)

Conglomerate “is a rock consisting of individual stones that have become cemented
together. Conglomerates are sedimentary rocks consisting of rounded fragements.”
(Wikipedia, 2006)
44
Glossary of Terms

Deposition see sediment.

Dike “is an intrusion into a cross-cutting fissure, meaning a dike cuts across other preexisting layers or bodies of rock, this means that a dike is always younger than the rocks
that contain it. Dikes are usually high angle to near vertical in orientation.” (Wikipedia,
2006)

Evaporite “is water-soluble, mineral sediments that result from the evaporation of bodies
of surficial water. Evaporite formations need not be composed entirely of halite salt. In
fact, most evaporite formations do not contain more than a few percent of evaporite
minerals, the remainder being composed of the more typical detrital clastic rocks and
carbonates.” (Wikipedia, 2006)

Extrusive “refers to the mode of igneous volcanic rock formation in which hot magma
from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently
into the atmosphere to fall back as pyroclastics or tuff.” (Wikipedia, 2006)

Farallon Plate “was an ancient, wholly oceanic tectonic plate, which began subducting
under the west coast of the North American Plate— then located in modern Utah— as
Pangaea broke apart during the Jurassic period. Over time the central part of the Farallon
Plate completely subducted under the southwestern part of the North American Plate. The
remains of the Farallon Plate are the Juan de Fuca Plate subducting under the northern
part of the North American Plate, the Cocos Plate subducting under Central America and
the Nazca Plate subducting under the South American Plate.” (Wikipedia, 2006)

Fossil “is the mineralized or otherwise preserved remains or traces (such as footprints) of
animals, plants, and other organisms.” (Wikipedia, 2006)

Gneiss “is a common and widely distributed type of rock formed by high-grade regional
metamorphic processes from preexisting formations that were originally either igneous or
sedimentary rocks. Gneissic rocks are coarsely foliated and largely recrystallized but do
not carry large quantities of micas, chlorite or other platy minerals.” (Wikipedia, 2006)

Gypsum “is a very soft mineral composed of calcium sulfate dihydrate, with the
chemical formula CaSO4·2H2O.” (Wikipedia, 2006)

Igneous “are rocks formed when molten rock (magma) cools and solidifies, with or
without crystallization, either below the surface” (Wikipedia, 2006)

Intrusive “is a body of igneous rock that has crystallized from a molten magma below
the surface of the Earth.” (Wikipedia, 2006)

Kunzite “(Spodumene) “is a pyroxene mineral consisting of lithium aluminium
inosilicate - LiAl(SiO3)2 - and is a source of lithium. It occurs as colourless to yellowish,
purplish or lilac kunzite (see below), yellowish-green or emerald-green hiddenite (see
below), prismatic crystals, often of great size.” (Wikipedia, 2006)

Kyanite “is a typically blue silicate mineral, commonly found in aluminium-rich
metamorphic pegmatites and/or sedimentary rock. Kyanite is a diagnostic mineral of the
Blueschist Facies of metamorphic rocks.” (Wikipedia, 2006)
45
Glossary of Terms

Lepidolite “(KLi2Al(Al,Si)3O10(F,OH)2) is a lilac or rose-violet colored phyllosilicate
mineral of the mica group that is a secondary source of lithium. It is associated with other
lithium-bearing minerals like spodumene in pegmatite bodies. It is one of the major
sources of the rare alkali metals, rubidium and caesium.” (Wikipedia, 2006)

Limestone “is a sedimentary rock composed largely of the mineral calcite (calcium
carbonate: CaCO3). Limestones often contain variable amounts of silica in the form of
chert or flint, as well as varying amounts of clay, silt and sand” (Wikipedia, 2006)

Lithified See lithification

Lithification “(from the Greek word lithos meaning 'rock')is the process whereby sediments
compact under pressure, expel connate fluids, and gradually become solid rock.”
(Wikipedia, 2006)

Metamorphic “is the result of the transformation of a pre-existing rock type, the
protolith, in a process called metamorphism, which means ‘change in form’.” (Wikipedia,
2006)

Morganite “is a pink coloured gem quality beryl, orange/yellow morganite is sometimes
found also, it turns pink upon high temperature treatment. (Wikipedia, 2006)

Muscovite “also known as potash mica, is a phyllosilicate mineral of aluminium and
potassium with formula: KAl2(AlSi3O10)(F,OH)2. It has a highly perfect basal cleavage
yielding remarkably thin laminae (sheets), which are often highly elastic.” (Wikipedia, 2006)

Obsidian “is an extrusive igneous rock. “Obsidian is a type of naturally occurring glass,
produced by volcanoes when a felsic lava cools rapidly and freezes without sufficient
time for crystal growth.” (Wikipedia, 2006)

Pegmatite “is a very coarse-grained igneous rock that has a grain size of 20 mm or more;
such rocks are referred to as pegmatitic. Most pegmatites are composed of quartz,
feldspar and mica.” (Wikipedia, 2006)

Plagioclase “is a very important series of tectosilicate minerals within the feldspar
family. Rather than referring to a particular mineral with a specific chemical composition,
plagioclase is a solid solution series, more properly known as the plagioclase feldspar
series (from the Greek "oblique fracture", in reference to its two cleavage angles). The
series ranges from albite to anorthite (with respective compositions NaAlSi3O8 to
CaAl2Si2O8),” (Wikipedia, 2006)

Quartz “is one of the most common minerals in the Earth's continental crust. It belongs
to the hexagonal crystal system, and is made up of silicon, (SiO2), tetrahedra. Quartz has
a hardness of 7 on the Mohs scale.” (Wikipedia, 2006)

Schist “form a group of medium-grade metamorphic rocks, chiefly notable for the
preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite,
and others. By definition, schist contains more than 50% platy and elongated minerals,
often finely interleaved with quartz and feldspar.” (Wikipedia, 2006)
46
Glossary of Terms

Sediment. See sedimentary.

Sedimentary “is one of the three main rock groups (along with igneous and metamorphic
rocks) and is formed in four main ways:
1. by the deposition of the weathered remains of other rocks (known as 'clastic' sedimentary
rocks);
2. by the accumulation and the consolidation of sediments;
3. by the deposition of the results of biogenic activity; and
4. by precipitation from solution” (Wikipedia, 2006)

Silicate “is a compound containing an anion in which one or more central silicon atoms
are surrounded by electronegative ligands. In geology and astronomy, the term silicate is
used to denote types of rock that consists predominantly of silicate minerals. Such rocks
include a wide range of igneous, metamorphic and sedimentary types.” (Wikipedia, 2006)

Sill “a tabular mass of igneous rock that has been intruded laterally between layers of
older rock.” (Wikipedia, 2006)

Siltstone “is a geological term for a sedimentary rock whose composition is intermediate
in grain size between the coarser sandstone and the finer mudstone.” (Wikipedia, 2006)

Subducting See subduction.

Subduction “is an area on Earth where two tectonic plates meet and move towards one
another, with one sliding underneath the other and moving down into the mantle”
(Wikipedia, 2006)

Tectonic “is a theory of geology which was developed to explain the observed evidence
for large scale motions within the Earth's crust.” (Wikipedia, 2006)

Tourmaline “is chemically one of the most complicated groups of silicate minerals. It is
a complex silicate of aluminium and boron, but because of isomorphous replacement
(solid solution), its composition varies widely with sodium, calcium, iron, magnesium,
lithium and other elements entering into the structure. Tourmaline is distinguished by its
three-sided prisms; no other common mineral has three sides.” (Wikipedia, 2006)

Unconformity “is a buried erosion surface separating two rock masses or strata of
different ages, indicating that sediment deposition was not continuous.” (Wikipedia, 2006)
47
Geologic Time Scale
Hofstra University . Retrieved November 04, 2006, from http://people.hofstra.edu/ website:
http://people.hofstra.edu/faculty/J_B_Bennington/2clab/timescale.gif
48
Geologic Time Scale of Southern California
© San
Diego Natural History Museum, 5/5/2017
49
Photo Gallery of Minerals
These spectacular photo’s pictured below are of minerals listed in this document.
Aquamarine (form of Beryl) Photo
courtesy of John Betts - Fine Minerals, New
Beryl Photo courtesy of John Betts Fine Minerals, New York, NY (2006)
York, NY (2006)
Kunzite Photo courtesy of Dr. Robert
Kyanite Photo courtesy of Dr. Robert
Lavinsky, [email protected]
The Arkenstone, PO BOX 450788, Garland, TX
(2006)
Lavinsky, [email protected]
The Arkenstone, PO BOX 450788, Garland,
TX (2006)
50
Photo Gallery continued.
Lepidolite Photo courtesy of John Betts -
Morganite Photo courtesy of Live Oak Minerals
Fine Minerals, New York, NY (2006)
(2006)
Muscovite Photo courtesy of Dr. Robert
Quartz Photo courtesy of Dr. Robert Lavinsky,
Lavinsky, [email protected]
The Arkenstone, PO BOX 450788, Garland, TX
(2006)
[email protected]
The Arkenstone, PO BOX 450788, Garland, TX (2006)
51
Photo Gallery continued.
Tourmaline (pink variety) Photo
courtesy of Dr. Robert Lavinsky,
Tourmaline (green variety) Photo
courtesy of Dr. Robert Lavinsky,
[email protected]
The Arkenstone, PO BOX 450788, Garland, TX
(2006)
[email protected]
The Arkenstone, PO BOX 450788, Garland,
TX (2006)
52
Bibliography
Abbott, L, Patrick. (1999).The Rise and Fall of San Diego, 1st Edition. San Diego, Ca. Sunbelt
Publications
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http://people.hofstra.edu/faculty/J_B_Bennington/2clab/timescale.gif
Bloom, Dave. (Speaker/Geologist). (2006), Interview with M. Nauss, (conversation), Discussion
of Canyon Sin Nombre Volcanic activity.
Deméré, A, Thomas. (2006). The Imperial Sea: Marine Geology and Paleontology. In Jefferson
& Lindsay, Fossil Treasures of the Anza-Borrego Desert (pp. 43-69). San Diego, Ca. Sunbelt
Publications
Farquharson, Phil, (Speaker/Geology Professor), (2006) Interview with M. Nauss,
(conversation), Discussion of Canyon Sin Nombre.
Leet, L. Don. (1982). Physical Geology, 6th Edition. Englewood Cliffs, NJ: Prentice-Hall
Geology map of California
Copyright [year] by Andrew Alden, geology.about.com, reproduced under educational fair use.
Remeika & Lindsay. (1992). Geology of Anza-Borrego: Edge of Creation, 1st Edition. San
Diego, Ca. Sunbelt Publications
Tarbuck & Lutgens. (2005). Earth: An Introduction to Physical Geology, 8th Edition. Upper
Saddle River, NJ. Prentice Hall
Salton Sea Authority http://www.saltonsea.ca.gov/histchron.htm
Swanger, Jeff. (Speaker). (2006). Interview with M. Nauss, (phone conversation), Discussion of
Oceanview Mine.
Andesite. (2006, November 5). In Wikipedia, The Free Encyclopedia. Retrieved 02:52,
November 22, 2006, from http://en.wikipedia.org/w/index.php?title=Andesite&oldid=85850947
alluvium. (n.d.). Dictionary.com Unabridged (v 1.0.1). Retrieved November 04, 2006, from
Dictionary.com website: http://dictionary.reference.com/browse/alluvium
53
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55
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56
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57