Brandon Barkdoll Lake Tahoe Basin and Cave Rock Geology 103

1. Lake Tahoe Basin, Cave Rock
Brandon Barkdoll
Geology 103 Field Assignment
Mark Lawler, Instructor

2. ContentsContents
 Lake Tahoe and Surrounding areasLake Tahoe and Surrounding areas
 MapsMaps
 Many species live in the Lake TahoeMany species live in the Lake Tahoe
BasinBasin
 Jeffrey PineJeffrey Pine
 ManzanitaManzanita
 Mallard DuckMallard Duck
 Black BearBlack Bear
 Cave Rock – GraniteCave Rock – Granite
 Near Cave Rock – Granite with LichenNear Cave Rock – Granite with Lichen
 Granite on Lake TahoeGranite on Lake Tahoe
 Banded HornfelBanded Hornfel
 Granite Composition ChartGranite Composition Chart
 ObsidianObsidian
 QuartzQuartz
 SiltstoneSiltstone

3. LAKE TAHOE ANDLAKE TAHOE AND
THE SURROUNDING MOUNTAINSTHE SURROUNDING MOUNTAINS
How were they created?How were they created?
The Lake Tahoe Basin was formed by geologic block
(normal) faulting about 2 to 3 million years ago. A geologic
block fault is a fracture in the Earth's crust causing blocks of
land to move up or down. Uplifted blocks created the Carson
Range on the east and the Sierra Nevada on the west.
Down-dropped blocks created the Lake Tahoe Basin in
between. Some of the highest peaks of the Lake Tahoe
Basin that formed during this process were Freel Peak at
10,891 ft (3,320 m), Monument Peak at 10,067 ft (3,068 m)
(the present Heavenly Valley Ski Area), Pyramid Peak at
9,983 ft (3,043 m) (in the Desolation Wilderness), and Mt.
Tallac at 9,735 ft (2,967 m). http://tahoe.usgs.gov/facts.html

4.  ““Following the faulting and volcanic period of the Basin, an Ice Age developed. Huge glaciers formed and movedFollowing the faulting and volcanic period of the Basin, an Ice Age developed. Huge glaciers formed and moved
down the V-shaped canyons on the western side of the lake. These glaciers scoured away loose rock and reshapeddown the V-shaped canyons on the western side of the lake. These glaciers scoured away loose rock and reshaped
the canyons into broad U-shaped valleys. The rock and gravel left behind at the sides and end of these meltingthe canyons into broad U-shaped valleys. The rock and gravel left behind at the sides and end of these melting
glaciers are called moraines. As these glaciers melted away, they also left behind brilliant bays, jagged peaks, glacialglaciers are called moraines. As these glaciers melted away, they also left behind brilliant bays, jagged peaks, glacial
polished ridges and crystal clear lakes”.polished ridges and crystal clear lakes”. Lake Tahoe Basin Mgt Unit - Learning Center. (n.d.). Retrieved June 16,
2015, from
 http://www.fs.usda.gov/detail/ltbmu/learning/?cid=stelprdb5109570
Lake Tahoe Basin Mgt Unit - Learning Center. (n.d.). Retrieved June 16, 2015, from
http://www.fs.usda.gov/detail/ltbmu/learning/?cid=stelprdb5109570
Lake Tahoe and surrounding mountains were created about 24 million years ago. The Sierra NevadaLake Tahoe and surrounding mountains were created about 24 million years ago. The Sierra Nevada
block was formed by tremendous uplifting. Two principal faults evolved: the eastern margin created theblock was formed by tremendous uplifting. Two principal faults evolved: the eastern margin created the
Carson Range, while the Sierra Nevada developed on the western side. From the “up thrown” faultCarson Range, while the Sierra Nevada developed on the western side. From the “up thrown” fault
blocks, the highest peaks in the region originated while “down thrown” block sank creating a large valleyblocks, the highest peaks in the region originated while “down thrown” block sank creating a large valley

5. Many types of rocks and plants are found in and around theMany types of rocks and plants are found in and around the
Lake Tahoe BasinLake Tahoe Basin
 More photos around the BasinMore photos around the Basin
Photos Brandon Barkdoll

6. Jeffrey PineJeffrey Pine
Jeffrey Pine, Pinus jeffreyi also known as Jeffrey’s Pine, yellow pine and black pine, isJeffrey Pine, Pinus jeffreyi also known as Jeffrey’s Pine, yellow pine and black pine, is
a North American pine tree. It is mainly found in California, but also in the westernmosta North American pine tree. It is mainly found in California, but also in the westernmost
part of Nevada, southwestern Oregon, and northern Baja California. It is named in honorpart of Nevada, southwestern Oregon, and northern Baja California. It is named in honor
of its botanist John Jeffrey. Jeffrey Pine becomes dominant at higher altitudes where theof its botanist John Jeffrey. Jeffrey Pine becomes dominant at higher altitudes where the
usually faster-growing ponderosa pine (Pinus Ponderosa) does not thrive. Jeffrey pine isusually faster-growing ponderosa pine (Pinus Ponderosa) does not thrive. Jeffrey pine is
more stress tolerant than the closely related Ponderosa pine. At higher elevations, onmore stress tolerant than the closely related Ponderosa pine. At higher elevations, on
poorer soils, in colder climates, and in dryer climates, Jeffrey pine replaces ponderosapoorer soils, in colder climates, and in dryer climates, Jeffrey pine replaces ponderosa
as the dominant tree https://en.wikipedia.org/wiki/Jeffrey_pineas the dominant tree https://en.wikipedia.org/wiki/Jeffrey_pine
»Photo credit Brandon Barkdoll
»Emerald Bay and Jeffrey Pine Lake Tahoe

7. Fossil record – evolution Jeffrey PineFossil record – evolution Jeffrey Pine
 Fossil record: Although fossil three needle pine material occurs as far back asFossil record: Although fossil three needle pine material occurs as far back as
Jurassic, there is none of it which has been definitely assigned to Pinus Jeffreyi.Jurassic, there is none of it which has been definitely assigned to Pinus Jeffreyi.
 Needles Indentified as Ponderosa Pine/Jeffreyi were reported from a glacial ageNeedles Indentified as Ponderosa Pine/Jeffreyi were reported from a glacial age
woodrat midden from Kings Canyon, CA (Cole 1983)woodrat midden from Kings Canyon, CA (Cole 1983)
 http://www.jstor.org/stable/41423399?seq=1#page_scan_tab_contentshttp://www.jstor.org/stable/41423399?seq=1#page_scan_tab_contents
 https://books.google.com/books?https://books.google.com/books?
id=GB7ng9K4gawC&pg=PA28&lpg=PA28&dq=fossil+record+jeffrey+pine&source=bl&ots=ux9MAZNzMD&sig=SO6ovHGq8jLyc_NV7IkgKid=GB7ng9K4gawC&pg=PA28&lpg=PA28&dq=fossil+record+jeffrey+pine&source=bl&ots=ux9MAZNzMD&sig=SO6ovHGq8jLyc_NV7IkgK
MEky9o&hl=en&sa=X&ei=oByHVfP1L8mDyQT3toGIDw&ved=0CCQQ6AEwAQ#v=onepage&q=fossil%20record%20jeffreyMEky9o&hl=en&sa=X&ei=oByHVfP1L8mDyQT3toGIDw&ved=0CCQQ6AEwAQ#v=onepage&q=fossil%20record%20jeffrey
%20pine&f=false%20pine&f=false

8. ManzanitaManzanita
 Actostaphylos patula, Greeleaf manzanitaActostaphylos patula, Greeleaf manzanita
You can grow a manzanita if you live in the Western United States. Manzanita is the common name for the genus
Arctostaphylos. There are more than forty species of Arctostaphylos in California not to mention all the cultivars,
subspecies and hybrids. They are very drought tolerant and evergreen, always looking green and healthy even in
the hottest, driest part of the summer. Manzanita (Arctostaphylos spp) is of the family Ericaceae.
https://en.wikipedia.org/wiki/Manzanita
Photos Brandon Barkdoll

9. Evolution of ManzanitaEvolution of Manzanita
 Genus evolution is relatively recent; however, in Hogan's tracing ofGenus evolution is relatively recent; however, in Hogan's tracing of
the genus evolutionary history: "convergent evolution patternsthe genus evolutionary history: "convergent evolution patterns
appear to complicate cladistic constructions for certain portions ofappear to complicate cladistic constructions for certain portions of
the genus cladogram.the genus cladogram.
 Fossil ancestors of theFossil ancestors of the ArctostaphylosArctostaphylos genus have been suggestedgenus have been suggested
to have occurred in the Middle Miocene, with modern speciesto have occurred in the Middle Miocene, with modern species
beginning to take shape in the Late Tertiary."beginning to take shape in the Late Tertiary."
https://en.wikipedia.org/wiki/Manzanitahttps://en.wikipedia.org/wiki/Manzanita

10. This type of duck is considered a "puddle duck" because it typically prefers shallow water such as creeks, ponds, andThis type of duck is considered a "puddle duck" because it typically prefers shallow water such as creeks, ponds, and
marshes. The male Mallard is easy to spot because of his glossy green head and narrow white collar. Usually you canmarshes. The male Mallard is easy to spot because of his glossy green head and narrow white collar. Usually you can
see the ducks flying south in formation for the wintersee the ducks flying south in formation for the winter
This photo was taken at
Taylor Creek
Brandon Barkdoll
Habitat: The mallard inhabits a wide range of habitat and climates, from Arctic tundra to
subtropical regions. It is found in both fresh- and salt-water wetlands, including parks, small ponds,
rivers, lakes and estuaries, as well as shallow inlets and open sea within sight of the coastline.
Water depths of less than 1 metre (3.3 ft) are preferred, birds avoiding areas more than a few
metres deep. They are attracted to bodies of water with aquatic vegetation.
Evolution: Apparently the mallard evolved very rapidly and recently, during the Late Pleistocene.
Mallard bones rather abruptly appear in food remains of ancient humans and other deposits of
fossil bones in Europe, without a good candidate for a local predecessor species.
https://en.wikipedia.org/wiki/Mallard
ANAS PLATYRHYNCHOS – Linnaeus, 1758

11. Ursus americanusUrsus americanus ,, Black Bear or American Black BearBlack Bear or American Black Bear
The only species of bears in California and Nevada are black bears. However, they do range in color from blonde to black, with cinnamon brownThe only species of bears in California and Nevada are black bears. However, they do range in color from blonde to black, with cinnamon brown
being the most common color in both states. There are an estimated 25,000 to 35,000 black bears in California and 200 to 300 In Nevada.being the most common color in both states. There are an estimated 25,000 to 35,000 black bears in California and 200 to 300 In Nevada.
Fossils: The ancestors of American black bears and Asiatic black bears diverged from sub bears 4.58 mya. The American black bear then splitFossils: The ancestors of American black bears and Asiatic black bears diverged from sub bears 4.58 mya. The American black bear then split
from the Asian black bear 4.08 mya. The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatlyfrom the Asian black bear 4.08 mya. The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania, greatly
resemble the Asiatic species of bear. https://en.wikipedia.org/wiki/American_black_bearresemble the Asiatic species of bear. https://en.wikipedia.org/wiki/American_black_bear
 This bear was about two feet from my house in South Lake Tahoe. There is a tree right behind our house that we call Bear Tree. TheThis bear was about two feet from my house in South Lake Tahoe. There is a tree right behind our house that we call Bear Tree. The
mothers will go high up with their cubs even during the summer to sleep all day. A mother and her cubs played in our yard a couple ofmothers will go high up with their cubs even during the summer to sleep all day. A mother and her cubs played in our yard a couple of
weeks ago as it was getting dark. The cubs were chasing each other around our tree.weeks ago as it was getting dark. The cubs were chasing each other around our tree.
 Habitat: Generally speaking, American black bears are forest dwellers. They can be found in deciduous, coniferous, or mixed forestHabitat: Generally speaking, American black bears are forest dwellers. They can be found in deciduous, coniferous, or mixed forest
regions from sea level to 10,000 feet in elevation. The habitat is usually characterized by thick understory vegetation and an abundantregions from sea level to 10,000 feet in elevation. The habitat is usually characterized by thick understory vegetation and an abundant
supply of fruit and nut bearing trees and shrubs. http://www.americanbear.org/Habitat%20-%20Home%20Range.htmsupply of fruit and nut bearing trees and shrubs. http://www.americanbear.org/Habitat%20-%20Home%20Range.htm
Photo Brandon BarkdollPhoto Brandon Barkdoll
Bear in the tree behind my house (Bear Tree)Bear in the tree behind my house (Bear Tree)

12. Cave RockCave Rock
How Cave Rock was formed: This large rock formation is located on the southeastern shore and is easily visible from
almost any point on the lake. Once a part of the neck of a volcanic vent that existed on the site about five million years ago,
Cave Rock is now named for the caves high up on its side. Cave Rock was first formed, roughly three million years ago, as
a volcanic vent. Lake level was initially hundreds of feet higher than it is now. Remarkably, these caves were carved out of
the rock by wave action of the lake over tens of thousands of years during that period!
History: Cave Rock consists mainly of granitic intrusive igneous rock that crystallized at depth in the earth’s crust and was
later uplifted to its current location The granite is overlain by andesitic volcanic rocks. Another way of putting it is that the
bedrock on the eastern side of Lake Tahoe is large Sierran Granite, simply because the Carson Range of mountains were
once part of the Sierra Nevadas, but have faulted off to their present location.
http://www.sierranevadageotourism.org/content/cave-rock/sieD297F2DC0D30D2CA8http://www.sierranevadageotourism.org/content/cave-rock/sieD297F2DC0D30D2CA8
All Photos this page taken byBrandon Barkdoll

13. Near Cave RockNear Cave Rock
 To the south of Cave Rock is this graniteTo the south of Cave Rock is this granite
rock:rock:
Photo Brandon Barkdoll
Lichen is also shown on the top of this large rock on HighwayLichen is also shown on the top of this large rock on Highway
50 south of Cave Rock. Lichen is not a single organism.50 south of Cave Rock. Lichen is not a single organism.
Rather, it is a symbiosis between different organisms - aRather, it is a symbiosis between different organisms - a
fungus and an alga or cyanobacterium.fungus and an alga or cyanobacterium.
Worldwide, over 20,000 species are known and over 3,000Worldwide, over 20,000 species are known and over 3,000
are known from Australia. Lichen colonies provide niches forare known from Australia. Lichen colonies provide niches for
numerous invertebrates, often the very tiny invertebrates,numerous invertebrates, often the very tiny invertebrates,
which are then eaten by larger invertebrates which, in turn,which are then eaten by larger invertebrates which, in turn,
are eaten by other creatures. Such lichen colonies are thusare eaten by other creatures. Such lichen colonies are thus
indirectly important in various food chains.indirectly important in various food chains.
Lichens are amongst the first organisms to colonize barrenLichens are amongst the first organisms to colonize barren
surfaces (e.g. road cuttings, rock outcrops and volcanic ash)surfaces (e.g. road cuttings, rock outcrops and volcanic ash)
and prepare these areas for later plants by trapping moistureand prepare these areas for later plants by trapping moisture
and windblown organic debris and then contributing to theand windblown organic debris and then contributing to the
organic deposits when they themselves die and decay.organic deposits when they themselves die and decay.
http://www.cpbr.gov.au/lichen/what-is-lichen.htmlhttp://www.cpbr.gov.au/lichen/what-is-lichen.html

14. Granite is a light-colored igneous with grains large enough to be visible with the unaided eye. It forms from theGranite is a light-colored igneous with grains large enough to be visible with the unaided eye. It forms from the
slow crystallization of magma below Earth’s surface. Granite is composed mainly of quartz and feldspar withslow crystallization of magma below Earth’s surface. Granite is composed mainly of quartz and feldspar with
minor amounts of mica, amphiboles and other minerals. This mineral composition usually gives granite a red,minor amounts of mica, amphiboles and other minerals. This mineral composition usually gives granite a red,
pink, gray or white color with dark mineral grains visible throughout the rock.pink, gray or white color with dark mineral grains visible throughout the rock.
East Shore of Lake TahoeEast Shore of Lake Tahoe http://geology.com/rocks/granite.shtml
 The large mineral crystals in granite are evidence that it cooled slowly from molten rock material. That slowThe large mineral crystals in granite are evidence that it cooled slowly from molten rock material. That slow
cooling had to have occurred beneath Earth's surface and required a long period of time to occur.cooling had to have occurred beneath Earth's surface and required a long period of time to occur.
»This granite outcropping on Lake Tahoe Shows Lichen on the top of the rocks. Crustose lichens
are markedly two dimensional and firmly attached to the substrate by their entire lower surfaces,
making it impossible to see a crustose lichen's undersurface. A crustose lichen looks very much
like a thin crust on the substrate. The bright orange Caloplaca is an example.
http://www.cpbr.gov.au/lichen/what-is-lichen.html
Photos Brandon Barkdoll

15. Banded Hornfel – Metamorphic RockBanded Hornfel – Metamorphic Rock
ThisThis picture was taken from the lake near Cave Rock on the East side of Lake Tahoepicture was taken from the lake near Cave Rock on the East side of Lake Tahoe
 Layers of light alternate with dark. Hornfels is called so because of its exceptional toughness andLayers of light alternate with dark. Hornfels is called so because of its exceptional toughness and
texture both reminiscent of animal horns. These properties are due to fine grained non-alignedtexture both reminiscent of animal horns. These properties are due to fine grained non-aligned
crystals with platy or prismatic habits. Hornfels is the group designation for a series of contactcrystals with platy or prismatic habits. Hornfels is the group designation for a series of contact
metamorphic rocks that have been baked and indurated by the heat of intrusive igneous massesmetamorphic rocks that have been baked and indurated by the heat of intrusive igneous masses
and have been rendered massive, hard, splintery, and in some cases exceedingly tough andand have been rendered massive, hard, splintery, and in some cases exceedingly tough and
durableformed by contact metamorphism of sandstones and shales by a granite intrusion.durableformed by contact metamorphism of sandstones and shales by a granite intrusion.
https://en.wikipedia.org/wiki/Hornfelshttps://en.wikipedia.org/wiki/Hornfels
 Fossil record: Rock consisting of alternating light and dark layers of iron-rich chert (hematite andFossil record: Rock consisting of alternating light and dark layers of iron-rich chert (hematite and
limonite) formed approximately 3,800 million years ago.limonite) formed approximately 3,800 million years ago.
A high-temperature, low-pressure metamorphic rock of uniform grain size showing no foliation.A high-temperature, low-pressure metamorphic rock of uniform grain size showing no foliation.
http://www.scientificpsychic.com/etc/geology-glossary.html#lethhttp://www.scientificpsychic.com/etc/geology-glossary.html#leth
Photo Brandon Barkdoll

16. Granite Composition ChartGranite Composition Chart
The chart below illustrates the range of granite compositionsThe chart below illustrates the range of granite compositions .. From the chart you can see that orthoclase, feldspar,From the chart you can see that orthoclase, feldspar,
quartz, plagioclase feldspar, micas, and amphiboles can each have a range of abundancesquartz, plagioclase feldspar, micas, and amphiboles can each have a range of abundances

http://geology.com/rocks/granite.shtml This chart illustrates the generalized mineral compositionhttp://geology.com/rocks/granite.shtml This chart illustrates the generalized mineral composition
of igneous rocks. Granites and rhyolites (compositionally equivalent to granite but of a fine grainof igneous rocks. Granites and rhyolites (compositionally equivalent to granite but of a fine grain
size) are composed mainly of orthoclase feldspar, quartz, plagioclase feldspar, mica andsize) are composed mainly of orthoclase feldspar, quartz, plagioclase feldspar, mica and
amphibole.amphibole.
Photo Brandon Barkdoll

17. ObsidianObsidian
 Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsicObsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic
lava extruded from a volcano cools rapidly with minimum crystal growth.lava extruded from a volcano cools rapidly with minimum crystal growth. Obsidian is a naturally occurringObsidian is a naturally occurring
volcanic glass formed as an extrusive igneous rock.volcanic glass formed as an extrusive igneous rock. https://en.wikipedia.org/?title=Obsidian#Origin_and_propertieshttps://en.wikipedia.org/?title=Obsidian#Origin_and_properties
 Obsidian is produced when felsic lava extruded from a volcano cools rapidly with minimum crystalObsidian is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal
growth. Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidiangrowth. Obsidian is commonly found within the margins of rhyolitic lava flows known as obsidian
flows, where the chemical composition (high silica content) induces a high viscosity andflows, where the chemical composition (high silica content) induces a high viscosity and
polymerization degree of the lava. The inhibition of atomic diffusion through this highly viscouspolymerization degree of the lava. The inhibition of atomic diffusion through this highly viscous
and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle.and polymerized lava explains the lack of crystal growth. Obsidian is hard and brittle.
hhttps://en.wikipedia.org/?title=Obsidian#Origin_and_propertiesttps://en.wikipedia.org/?title=Obsidian#Origin_and_properties
Photo Brandon Barkdoll

18. ObsidianObsidian
 Composition: Obsidian is mineral-like, but not a true mineralComposition: Obsidian is mineral-like, but not a true mineral
because as a glass it is not crystalline; in addition, its composition isbecause as a glass it is not crystalline; in addition, its composition is
too complex to comprise a single mineral. It is sometimes classifiedtoo complex to comprise a single mineral. It is sometimes classified
as a mineraloid. Though obsidian is usually dark in color similar toas a mineraloid. Though obsidian is usually dark in color similar to
mafic rocks such as basalt, obsidian's composition is extremelymafic rocks such as basalt, obsidian's composition is extremely
felsic. Obsidian consists mainly of SiO2 (silicon dioxide), usuallyfelsic. Obsidian consists mainly of SiO2 (silicon dioxide), usually
70% or more. Crystalline rocks with obsidian's composition include70% or more. Crystalline rocks with obsidian's composition include
granite and rhyolite.granite and rhyolite.
 History: Because obsidian is metastable at the Earth's surface (overHistory: Because obsidian is metastable at the Earth's surface (over
time the glass becomes fine-grained mineral crystals), no obsidiantime the glass becomes fine-grained mineral crystals), no obsidian
has been found that is older than Cretaceous age. This breakdownhas been found that is older than Cretaceous age. This breakdown
of obsidian is accelerated by the presence of water.of obsidian is accelerated by the presence of water. https://en.wikipedia.org/?https://en.wikipedia.org/?
title=Obsidian#Origin_and_propertiestitle=Obsidian#Origin_and_properties

19. QuartzQuartzQuartz is one of the most common and well-known minerals on earth.
It occurs in basically all mineral environments, and is the important
constituent of many rocks. Quartz is also the most varied of all
minerals, occurring in all different forms, habits, and colors. There are
more variety names given to Quartz than any other mineral. Although
the Feldspars as a group are more prevalent than Quartz, as an
individual mineral Quartz is the most common mineral
Quartz occurs in virtually all mineral environments, and may
be associated with almost every mineral
http://www.minerals.net/mineral/quartz.aspx#sthash.fELtNy2z.dpuf
Granite is an igneous rock that is composed of four
minerals. These minerals are quartz, feldspar, mica, and
usually hornblende.
Photo Brandon Barkdoll

20. QuartzQuartz
 The largest amount of quartz is found in Metamorphic rocksThe largest amount of quartz is found in Metamorphic rocks
 There are high concentrations of quartz in sedimentary rocksThere are high concentrations of quartz in sedimentary rocks
 The amounts of quartz vary in igneous rocksThe amounts of quartz vary in igneous rocks
 Metamorphosis is the only major process in which quartz is either produced or consumed andMetamorphosis is the only major process in which quartz is either produced or consumed and
disappears from the environment during the formation of new minerals.disappears from the environment during the formation of new minerals.
http://www.quartzpage.de/gen_rock.htmlhttp://www.quartzpage.de/gen_rock.html
 Quartz Fossil Record:Quartz Fossil Record:
 Fractured CrystalsFractured Crystals
These crystals, often called "shocked quartz," show a distinctive pattern of fracturing caused byThese crystals, often called "shocked quartz," show a distinctive pattern of fracturing caused by
high-energy impacts or explosions.high-energy impacts or explosions.
 Some scientists maintain that the fracture pattern in these quartz crystals could only have beenSome scientists maintain that the fracture pattern in these quartz crystals could only have been
caused by a massive asteroid or comet impact. The pattern is prevalent in quartz found at or nearcaused by a massive asteroid or comet impact. The pattern is prevalent in quartz found at or near
the Cretaceous/Tertiary (KT) boundary, the geological layer deposited at the time of thethe Cretaceous/Tertiary (KT) boundary, the geological layer deposited at the time of the
extinction. http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/asteroid.htmlextinction. http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/asteroid.html

21. SiltstoneSiltstone
 Glen Alpine Falls Fallen Leaf AreaGlen Alpine Falls Fallen Leaf Area
Photo Brandon Barkdoll
Siltstone is a sedimentary rock which has a grain size in the silt range, finer
than sandstone and coarser than clay stones. https://en.wikipedia.org/?
title=Siltstone
They are "mud rocks" composed of silt and clay particles slowly deposited
through suspension in calm waters.
http://classroom.synonym.com/environment-likely-form-siltstone-shale-
6627.html
Composition: Quartz, clay, clay minerals, Color Reddish brown.
Depositional Environment Flood Plain, Delta, or Mid-continental shelf
http://core.ecu.edu/geology/harper/Sedimentary/display_new.cfm?ID=17
Fossil Record: Fossils are well preserved in mud rock formations, because the
fine-grained rock protects the fossils from erosion, dissolution, and other
processes of erosion. Deposited during the Paleozoic.
https://en.wikipedia.org/wiki/Mudrock

22. ResourcesResources

(n.d.). Retrieved June 16, 2015, from https://en.wikipedia.org/wiki/Jeffrey_pine(n.d.). Retrieved June 16, 2015, from https://en.wikipedia.org/wiki/Jeffrey_pine
 Cave Rock - Sierra Nevada Geotourism MapGuide. (n.d.). Retrieved June 15, 2015, fromCave Rock - Sierra Nevada Geotourism MapGuide. (n.d.). Retrieved June 15, 2015, from
http://www.sierranevadageotourism.org/content/cave-rock/sieD297F2DC0D30D2CA8http://www.sierranevadageotourism.org/content/cave-rock/sieD297F2DC0D30D2CA8
 Tahoe -- Cave Rock Earthcache. (n.d.). Retrieved June 12, 2015, fromTahoe -- Cave Rock Earthcache. (n.d.). Retrieved June 12, 2015, from
http://www.geocaching.com/geocache/GC25JA8_tahoe-cave-rock-earthcache?guid=28ce0efa-http://www.geocaching.com/geocache/GC25JA8_tahoe-cave-rock-earthcache?guid=28ce0efa-
8180-4801-b74b-9382ac0564008180-4801-b74b-9382ac056400
The American Bear Association Home Page (Web Pages2/index). (n.d.). Retrieved June 7, 2015,The American Bear Association Home Page (Web Pages2/index). (n.d.). Retrieved June 7, 2015,
from http://www.americanbear.org/Habitat - Home Range.htmfrom http://www.americanbear.org/Habitat - Home Range.htm
Black Bear Facts. (n.d.). Retrieved June 7, 2015, fromBlack Bear Facts. (n.d.). Retrieved June 7, 2015, from
http://www.tahoewildbears.org/black_bear_facts.htmhttp://www.tahoewildbears.org/black_bear_facts.htm
 Lake Tahoe Basin Mgt Unit - Learning Center. (n.d.). Retrieved June 16, 2015, from
http://www.fs.usda.gov/detail/ltbmu/learning/?cid=stelprdb5109570
 Granite. (n.d.). Retrieved June 15, 2015, from http://geology.com/rocks/granite.shtml
 Facts About Lake Tahoe. (n.d.). Retrieved June 15, 2015, from http://tahoe.usgs.gov/facts.htmlFacts About Lake Tahoe. (n.d.). Retrieved June 15, 2015, from http://tahoe.usgs.gov/facts.html
 (n.d.). Retrieved June 7, 2015, from(n.d.). Retrieved June 7, 2015, from https://en.wikipedia.org/wiki/American_black_bearhttps://en.wikipedia.org/wiki/American_black_bear

23. Resources continuedResources continued
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