Essay Topic:

The main characteristics and physical geography of the Mohave Desert.

Essay Questions:

Where is the Mohave Desert located?

How do two different ecosystems exist in one desert?

How has the human factor influenced the Mohave ecosystem?

Thesis Statement:

The beauty of Mohave is known all over the world. As all of the four deserts share ground water resources, and Mojave is not an exception, the flora and the fauna takes the breath away. As it has been already said Mohave is a place of merging of the cool Great Basin and the hot climate of the Sonoran Desert.

The Physical Geography of the Mohave Desert Essay

 

 

1. Introduction

2. Basic map information

3. Atmospheric characteristics

a. -Insolation

b. -Albedo

c. -Overall temperature

4. Climate and weather patterns in Mohave

a. -Climate calcification

b. -Factors affecting the climate

c. -Storms

5. Hydrology and biology of the desert

a. -Water resources

b. -Plants

c. -Animals

6. Ecosystems and the soils of the desert

a. -Ecosystems and the food chains

b. -The human factor

c. -Soil of the desert

7. Geomorphic processes

a. -Rocks in the area

b. -Folding and faulting of the area

Introduction: A desert is a word used to define a place that has poor vegetation and gets lesser than 10 inches of rain precipitation per year. Mohave completely fits this definition. But what is Mohave? If you ever hear about the territory in North America that occupies more than 25,000 square miles, fits the definition of a desert, includes the territory of four states and lies between Sonoran Desert and Great Basin, be sure to know that it is the Mohave Desert. The Mohave Desert is situated on the territory of the United States of America and is a well-known place, though sometimes considered not to be a desert on its own right [2]. It is also known as one of the four North America main deserts. They are: Great Basin, Mohave, Chihuahuan and Sonoran deserts. This desert is a very significant place for scientific research due to the presence of plants that can be found nowhere else on the planet and due to the peculiarity of the climate of Mohave. The beauty of Mohave is known all over the world. As all of the four deserts share ground water resources, and Mojave is not an exception, the flora and the fauna takes the breath away. As it has been already said Mohave is a place of merging of the cool Great Basin and the hot climate of the Sonoran Desert. Owing to this intersection of two different ecosystems, makes a new one. The Mohave Desert forms a unique desert ecosystem and is also the smallest out of the four mentioned North America deserts.

 

Basic map information.The Mohave Desert is a territory situated in the Southwest of the North America continent. It is in the Southeastern California at 35° to 36° latitude North and 115° to 117° longitude East [1]. It includes the territory not only of California, but also parts of Nevada, Arizona and Utah. Sierra Nevada Mountains that play a great role in the Mohave’s climate formation are situated to the west of the desert. The closest larger water body is the Colorado River, which is situated on the east of the desert. Its elevation ranges from 282 feet—lowest in the North America –Death Valley to over 11,000 feet [3]. The Mojave Desert is connected to the Tehachapi along with the San Gabriel and San Bernadino mountain ranges. The borders of the mountains and the desert are quiete visible, is especially stressed by the San Andreas and the Garlock faults[5].

 

Atmospheric characteristics.The main atmospheric characteristic of the Mohave Desert is the extreme variation in daily temperatures; lower atmosphere layers provide hot dry windy air throughout the whole year and the rise of the humidity level throughout the winter season. Analyzing the atmospheric characteristics it is very important to point out the role of the sun and the radiation that the territory of the Mohave Desert gets from it.

 

-Insolation

The incoming solar radiation reaching the territory of the desert is high due to the peculiarities of the location of the desert. The atmosphere charges with this radiation and gets ready to reflect it on the surface of the desert. The surface of Mohave gets direct insolation, due to the absence of clouds and other atmosphere components, especially in summer. The only time the desert gets the balance is its rainy winter.

 

-Albedo

Insolation is closely related to albedo. The albedo is considered to be a definite measure of the reflectivity of a body, in this case it is the territory of the desert.[4] The amount of the electromagnetic radiation reflected in the desert is high. The albedo percentage of the Mohave Desert is considered to be – 25%; due to this the soil needs to protected from subsequent soil heating. The large amount of albedo in the Mohave Desert is in an intercoupling with the climate of the tropical climate of this desert. The shrubs that grow in the desert are also the part of the protection of the soil against the solar radiation. The more insolation occurs the more the albedo decreases producing soil heating.

 

-Overall temperature

The temperature in the Mohave Desert has a very extreme characteristic. It is not in summer and cold in winter. In wintertime in some parts of Mohave it is even possible to find snow. During wintertime the temperature gets very close to 0?F. But generally speaking, the tempature ranges from 15?F in winter to 110?F in summer, the maximum known is 134? F level in Death Valley[5].The hot summer temperatures start in May and end in October.The temparature is usually higher than 100? F. The big difference between the temperatures is explained by the great amount of rains in Mohave in winter.

Climate and weather patterns in MohaveAs the climate conditions in the Mohave Desert are very special and it may be even said dual, therefore there is not one, but several weather patters in the region.

-Climate calcification.The climate of Mohave belongs to the Dry tropical climate. It is characterized by the equatorial subtropical high-pressure belt and trade winds. This usually produces the non-raining, dry climate. The desert is usually called “high” desert. It is known for it day-night temperature fluctuations [Bull, 1991]. The desert’s humidity is usually below 40%, except winter nighttime and the summer rains caused by storms when it exceeds 50%.

 

-Factors affecting the climateThe Mohave Desert is included to the group of the “shadow effect” deserts. The reason for that it is really situated in the “shadow” of the Sierra Nevada. As the wind approaches the mountains it has no other way out then to rise to the top of the mountains and therefore to cool and get a lot of moisture, but when it passes through mountain range it loses almost all of its moisture and gets very dry by the time it reaches the desert. The air gets warm and through this the formation of clouds is prevented. This is one of the main peculiarities of Mohave – clears skies. Some of the summer rains are called "Monsoon" rains and the winter rains are Pacific Northwest style one’s.

-Storms

The most frequent storms in the desert start in winter. They follow the jet stream of the Pacific Ocean and that is how they get to the region of the desert. Nevertheless, it is very important to mention that summer storms in the Mohave Desert are very intense and way more intense than winter storms. As the situation with the precipitation in summer is hard these summer storms dump large amounts of precipitation in short periods of time. They are the most valuable for the desert and balance the erosional and depositional capacities of the desert [Bender 1982]. Another common thing in this desert in summer is the high velocity winds that sweep the basalt mountains, plains, sand dunes, marshals and sinks of the desert [3]. Tropical storms or Chubacos may have a small affect on the weather when they arouse to the south of the desert. “El Nino” also causes the raise of the level of rainfalls in the desert. The approximate rainfall of the Mohave Desert for the last 20 years has been 3.5 inches. It still remains very interesting concerning the matter of the change of climate during different seasons.

 

Hydrology and biology of the desert.Being a desert Mohave still has a lot to do with hydrology. The desert suffers a lot of evaporation. The level of evaporation exceeds the level of precipitations. This makes a cause for the living forms seek sources of water in the desert.

 

-Water resources

Despite its aridity, the Mojave has long been a center of alfalfa production, fed by irrigation coming from groundwater and nowadays from the California Aqueduct.[5] The start of ground waters in the Mohave desert are to be found in the Great Basin, which constantly feeds the, with more and more water due to its amount in the Great Basin. The hydrographic Great Basin includes most of the Mojave Desert and exceeds 500,000 square kilometers [Morrison, 1991]. There are channels that are in their majority bedrock-controlled that provide some water for the desert. The majority of the water channels terminate in the basin. All the ground waters eventually fall into the Colorado River. The ground waters feed the plants and through them the animals of the desert. Lake Mohave and Lake Meal are well known in the association with this desert. Lake Meal is the center of water resources of the desert and an absolutely beautiful place. It is a place of contrasts between the sand dunes and water. The WRC (Water resource center) is the research group that controls the water distribution throughout the Mohave Desert. It improves the hydrologic systems and does not damage the arid areas. There is a number of wells through Mohave, that in spite of bringing positive aspects into the life of the desert make a lot of damage to it, too, exposing the soil to erosions, etc. The other resources are natural – the water resulting from the rains and storms. Altogether they give a general level of 3.5 inches of rainfall per year. The general precipitation usually ranges from 2 to 4 inches per year.

 

-Plants

Due to the water resources peculiarities the vegetation of the Mohave region is very diverse. Nevertheless most of it is a shrub. Most of them are xerophytes. It starts with a regular cactus, able to store water and ends up with Joshua tree that is nowhere else to be found on the planet. The brightest examples of the Mohave Desert vegetation are the next: Brittle Bush (Incienso), Common Salt-bush (Alkali Saltbush), Creosote bush, Mojave Aster, Triangle-leaf Bursage and of course Joshua tree. To completely understand the diversity it is important to mention a couple of facts about some plant. Brittlebush is 2-5 feet shrub that is very protective against the heat and cold. It gets any moisture that is located in the air, and reduces the quantity of water lost to dry air. It is a miniature form of a sunflower. Some animals eat its seeds. Joshua tree is a yucca, but it is the largest yucca and as it has been mentioned before is to be found in the Mohave Desert only. It can be as high as 40 feet with a maximum diameter of 3 feet. It also bears flowers, like most of the plants in the Mohave Desert.

 

-Animals

The animals of this desert are similar to the ones that may be found in other deserts: bighorn sheep, desert kit fox, coyote, spotted skunk, spotted bat, black-tailed jackrabbit, kangaroo rat, and white-footed mouse and the disappearing ground squirrel. Among them it is important to outline the Coyote, the Desert Tortoise and the Mohave Rattlesnake. The medium size of the rattlesnake is 3 feet. They are usually greenish or sometimes brownish. The venom of the snake is very strong and may without any doubts be called the most dangerous snake in the whole North America continent. The desert tortoise is usually no more than 15 inches in length and up to 6 inches high, live in burrows. It is very non-adaptive and makes very little posterity. It is “threatened” specie under the California state Endangered Species Act in 1989 and the federal Endangered Species Act in 1990. There is so much life in the desert that is just not visible, too.

Ecosystems and the soils of the desert .Mohave has a unique desert ecosystem under the influence of which unique animals and plants are presented there. The ecosystem, as it includes flora and fauna, also includes the soil of the desert.

-Ecosystems and the food chains.The desert ecosystem of Mohave with its climate is characterized by a high activity of the animals and plants in summer and very low activity during winter. Most of the animals throughout spring and summer store food and get ready for the future dormancy. The major peculiarity of the desert is the food chain. It is built in a way very comfortable for this time of desert. Such species as coyotes and Mohave rattlesnakes eat rats and other rodents and other small animals. When there are no rodents found, especially in wintertime, coyotes eat plants, insects and even reptiles to save themselves. When winter comes the Mohave rattlesnake learns how to get inside the minks of the rodents in order to eat them. The rats and rodents in their turn eat seeds of the native shrubs and some insects. Desert Tortoises eat different herbs and even cactus.

-The human factor.Though there are a lot of organizations with the goal of preservation of the existing ecosystem and reducing the human influence to the possible minimum the human effect is still strong and damaging. For instance the 90% disappearance of the desert tortoise is the result of the urban expansion and the exploration of the desert. As this species are not adaptive at all is causes a lot of problems, because vehicles destroy their food and change their habitats. A lot of efforts have been made on the prevention of the urban expansion through the desert, but the effect has not been really weighty.

-Soil of the desert.Soils include aridisols and entisols; this is accompanied by thermic and hyperthermic soil temperature regimes. The foothills function on the aridic soil moisture regime. Most of the territory is a salt-affected soil [Machette 1985]. Quartz and feldspar are believed to be in the Mohave Desert, too. The lower soil layers are rich with moisture owing to which the plants get the required water for their existance. Mining of hard rock minerals and borax is also presented in the desert, too.

Conclusion:The desert is full of isolated mountains, plateaus, alluvial fans, playas, basins, and dunes. The desert elevation ranges from 300 ft below sea level to 11,000 ft above sea level. This means that it is from –91 meters up to 3,344 meters. The zone is partly seismically active and this causes the changes in its elevations.-Rocks in the area.The rocks found in the area of the Mohave Desert are diverse. But most of all belong to the sedimentary and granite rocks. Their geologic age relates to the Phanerozoic Eon/ Cenozoic Era, especially to the Quaternary period. The main epoch is the Holocene epoch (from 10 000 years till today). Such rock representatives as clay, silt, and eolian sand in Kelso Dunes belong to the Quaternary period. The other rocks to mention are the rock walls in the canyons of the Coso Range with ancient images on them.-Folding and faulting of the area Mountain ranges of the desert are stratified sedimentary rocks, some are granitic or metamorphic masses, others result from recent volcanic rock. A majority of the area contains the combinations of these materials. Some of them were formed on the basis of vertical fault planes; others are the result of folding. Therefore the desert represents a division on the faulting and folding obtained rocks.This desert is a bottomless cup of surprises. A there is so much more to say about the “Great” Mohave Desert.