GLG 101 Final Template

7/29/2019 GLG 101 Final Template

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Geology of Nevada

By Michaela Vos

University of Phoenix

01/01/2011


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Geological Features & Events

One thing about the topography and geologic structure in Nevada is that it is tied to the climate of this desert state.

This is because of the Sierra Nevada mountains (which is part of the Pacific Mountain system), and other high mountains trap

moisture that comes off the pacific ocean. Nevada is actually the driest state in the nation if you can believe it. Because of the

fossils found in different areas of Nevada and California geologists estimate that the Sierra Nevada mountains only rose the

its current elevations within the last six million years.


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Geological Feature

The most prevalent rock type of the Sierra Nevada mountains are mostly made up of

igneous granite rock.

Igneous granite is a felsic rock, which means that the mineral composition of the

rock type is mostly feldspar.


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Geologic Time

It is hard to say how old my geologic feature is, because the formation of the mountains started about 100 million

years ago.

The absolute age of the Sierra Nevada Mountains is at leas 40 million years old. We know this because one of the

methods used was when the scientists conducted a chemical analysis in the mid 1800s during the California gold rush of

ancient raindrops!


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Geological Event

What geological event that occurred that created the Sierra Nevada mountains was a few things, first about 250

million years ago there was the plate tectonics. These plate tectonics are also what caused the seismic and volcanic activity

that we see today. Because of all the pressure and friction the crust of the Pacific plate ended up melting, creating plumes of

liquid plutonic rock which floated up to the surface. Then the plutons came together to form the batholiths that is the Sierra

Nevada Mountains. So about 80 million years ago, as the batholiths started to rise the layer of marine sedimentary rock which

covered the mountain slowly eroded away and deposited in the valley. There are still remnants of the marine rock that still

cling to mountaintops.


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Weathering and Erosion

The types of weathering and erosion that have effected the Sierra Nevada Mountains are Chemical and

mechanical weathering as well as water. Although those three factors play a role in the appearance, the major

type of weathering and erosion would be glaciation, this is because it has shaped the terrain of the mountains as

well as removed most of the soil.


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Igneous Rocks

McKee (2010) Tertiary igneous rocks in Nevada are of two fundamentally different petrochemical types

that are the result of two regional tectonic regimes active in western North America during the latter half of the

Cenozoic. Many hydrothermal mineral deposits in Nevada clearly reflect these two tectonic regimes and their

associated igneous activity. The older petrochemical igneous type is of late Eocene through Oligocene age, is

intermediate calc-alkalic in chemistry, and is related to subduction of the Pacific (Farallon) plate beneath the

continental North American plate (Ch.6, Para. 1-2).


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Sedimentary Rocks

According toNevada Bureau of Mines and Geology Today the area is underlain primarily by volcanic and

sedimentary rocks that are between about 24 and 11 million years old (part of the Miocene Epoch, Tertiary Period, Cenozoic

Era), and there are no active volcanoes nearby. The most abundant rocks are white and pink tuff (rock composed of ash,

crystals, rock fragments, and pumice violently erupted from a volcano); gray, green, and brown andesite (lava flows and

feeder intrusions to the lava flows); and white, bedded sandstone composed largely of volcanic debris. Quaternary (less than

1.8 million years old) alluviumunconsolidated sediments eroded from older rocksfills stream bottoms and underlies

gentle fan shaped slopes leading from the highway up to the bedrock areas. Some older sedimentary rocks (chert, argillite,

shale, siltstone, sandstone, and limestone), which were deposited during the Cambrian to Devonian Periods, between about

500 and 350 million years ago, occur approximately one kilometer to the west of this locality and occasionally as rock

fragments in the tuffs. Erosion during the last several thousand years has sculpted the tuffs into unusual and picturesque

shapes (GEOLOGY, para. 3).


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Metamorphic Rocks

Boone (2010) Metamorphic rocks, common to uncommon around Las Vegas depending on the type, are formed

by changing the structure of pre-existing rock. This usually is due to high pressure and temperatures deep within the crust of

earth, but rocks can be chemically altered. Metamorphic rocks are never melted in the process, just heated and squeezed such

that the minerals in the original rock are changed (Metamorphic Rocks, Para. 1).


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Water, Desert, and Glaciers

A significant desert of my region, and the process involved with creating it would be the whole state. Nevada is

known for being one huge desert, although there are three specific deserts that go across it which are the Black Rock Desert,

the Mojave Desert, and the Great Basin Desert which covers most of Nevada and was formed by a volcano and earthquake.

Christensen (n.d.) Ecologists distinguish between the Great Basin Desert - the cold, northern, high-elevation desert

dominated by sagebrush - and the Mojave Desert - the hot, southern, low-elevation desert of cactus and creosote bush. But

the two deserts blend into each other (What is the Great Basin, Para. 9). These deserts were created as a result of very high

mountains. Because of the mountains the costal winds from the ocean are unable to reach Nevada, making Nevada the driest

state in the United States (as mentioned before).

Black Rock Desert Great Basin Desert

Mojave Desert


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Resources

Resources that are abundant in this region would include natural energy because of the deserts sun. Also, Nevada

is abundant in mineral resources. Nevada also has amazing scenery and climate. There is also Las Vegas' Nevada which has

many casino's and nightclubs which provide the state with a thriving tourist industry. Nevadas wealth mainly comes from

the tourism to Reno, Las Vegas, Virginia City, and Lake Tahoe. With out the tourism Nevada would loose a lot of its

income.

Scenery

Virginia City


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Conclusion

The reason I choose the Sierra Nevada Desert was because of the beauty within the mountains. You drive to Carson

City Nevada and look up and all you see is this majestic beauty covered in snow. Nevada is full of openness and wild

animals, and un-touched land. You can actually drive and not see any buildings, just wild horses running through the desert.

The mountains are part of the reason we have this desert and the beauty within. You can look up at night and actually see the

billions of stars because there arent a lot of lights out in the desert. I wouldnt want to live any where else.

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