Desert Landforms
We were taken to an area of the desert approximately 20 kilometers
inland from Jeddah. On arrival, we were asked to carry out practical
investigations of the landforms and landscape in the immediate area,
in order to find evidence of river processes and resulting landform
such as erosion, transportation, weathering and depostion . these
investigations took place in a valley (“wadi”), which is an
intermittent watercourse, during the dry season. To carry out our
measurements, we devised the following equipment before hand:
* A clinometer, to measure the gradient along the “wadi” and its
cross profile (long profile).
* A stone board, in order to measure the size of rocks
* A chart to classify the chosen rocks
* A quadrate to help choose rocks randomly
Before leaving to the “Wadi”, we prepared a list of hypotheses. Our
aim was to prove or disprove them after collecting and analyzing our
data.
HYPOSTHESES:
1. the stones found at the top of the “wadi” are larger then those
at the bottom
2. the stones found at the top of the “wadi” are more angular than
those at the bottom.
3. the slope at the top of the “wadi” is “v-shaped”.
4. the slope at the bottom of the “wadi” is “u-shaped”.
5. weathering is more common at the top, as there is more exposure.
6. the angle of cross section will be smaller where the load is more
angular.
7. there is evidence of attrition taking place.
8. the smaller the stone the more rounded it is.
9. the larger the stone the more angular it is.
10. there is evidence of exfoliation (onion weathering) becau...
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...paring it with a chart for assessing their
shape.
Measuring the size of the stones:
The chosen stone was placed vertically on the stone board. Its long
axis was measured and noted down.
Measuring the gradients alond the “wadi”
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This is also known as the long profile. One person stood in a specific
place. Another person stood ten metres away, facing the first person.
The clinometer was held horizontally and an immediate reading of the
angle of the slope was taken.
Measuring the cross profile of the “wasi”
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Two people stood ten metres away from each other, this time, across
the “Wadi”. Again, the clinometer was used to measure the angle of
slope. A second reading was taken, on the opposite side of the “Wadi”.
1. 225 MY : Weathering and erosion of very old folded rocks on an area
First theory that comes from astronomical angle is usually the more believed one since there was so many close in content interpretations of it with tiny variations. In the structure of this ancient monument, several types of stones can be observed. There are: Sarsen stones, Trilithon, Blue stones, an Altar...
Desert Solitaire aims to draw attention to the activities of a man voluntarily isolated in nature. It seeks to identify the strife that Abbey faces with modern day human’s treatment of his nature. As such, the argument that Abbey poses in one his earlier chapters Rocks is, that the Modern Day man is destructive and cannot be trusted to preserve nature as is.
Desert pavements are common landforms in arid regions. They consist of flat or sloping surfaces where stones are closely packed angular or rounded, and generally exhibit low relief (Mabbutt, 1977). Pavements tend to form on both alluvial fan toposequences and on weathering volcanic flow fields in arid regions. Soils are often found under desert pavements and they play an important role in the evolution of pavements (McFadden et. al., 1987). In the past there have been several theories as to the formation pavements and soil development beneath them. Deflation, or the erosion of finer grained particles from a surface, stone concentration by wash erosion and upward displacement of stone due to shrink and swell clay characteristics were at one time believed to be the main factors in the formation of desert pavements (Mabbutt, 1977). However, more recent research has shown that desert pavements are born and maintained at the surface, and that the soil below them is mainly eolian in origin. Slow accretion of eolian dust below the pavement is a process that eventually develops cumulate horizons. Eolian dust in environments where pavements often develop is rich in carbonate salts and clays due to the fact it often originates from nearby playa lake evaporate basins (McFadden et. al., 1987). Soils that form below the pavements over time develop calcic horizons and clay rich structure due to the influx of these eolian fines through the pavement surface. In turn the development of mature or plugged calcic horizons effects the form of the pavement surface because it alters the water drainage infiltration rate and causes pavements to decline.
In the poem Desert Places by Robert Frost, the author describes the scenery in which he came across with. It was on a winter day, and the day was turning into a night. As he went across a field, he saw that the ground was almost all covered in snow. But then he noticed a few weeds and stubble on the ground.
In the article, “The Great American Desert”, Edward Abbey (1977) is trying to convince the general public that the desert is not a place for humans to explore. He talks a lot about the dangers of the desert and tries to convince the readers that the desert is not worth wasting your time and going and visiting. I disagree with Abbey. Anyone who has some knowledge about the desert and takes a class or is accompanied by an expert who knows a lot about the desert should be able to venture out in the many great American deserts.
As humans, we need food to survive. This is a basic need and want and has always been primarily done by farming the land. That farmed land requires sunlight, nutrients, and fresh water. If one of these three criteria is missing, the land is no longer able to birth vegetation. The biggest issue we face here in Canada is desertification. This term means that the land being classified with this is losing its water either to drought or to human causes. Desertification is a form of land degradation and is found to be an issue all over the globe. These dry lands are not just centered on a small percentage of people but affect up to half of the world’s population. This type of soil erosion is due to many factors. The biggest is the latitude of the area under concentration. Of course the closer you are to the equator the hotter and less precipitation is going to reach the land and this also affects natural weather cycles. The sad thing is however that where there is desertification, poverty will not be far. This makes sense for the reason we have poverty is because there are people without food and shelter. This connects to the lack of vegetation for with desertification the food and materials needed cannot grow to make a successful civilization. Looking at what causes desertification we can at least attempt to reverse the results. Desertification is caused by human error by globalizing prematurely.
Ethiopia is located in the Eastern region of Africa. According to the Embassy of Federal Democratic Republic of Ethiopia, Ethiopia lies between the geographical coordinates of 3’ and 14. 8’ latitude and 33’and 48’ longitude. Ethiopia encompasses a majority of the area known as the Horn of Africa. The CIA World Factbook states that Ethiopia is approximately 1,104,300 square kilometers (686,180 miles). To give a better perspective of the sheer size of this country, it is about twice the size of the state of Texas. The CIA World Factbook also states that Ethiopia’s area ranks 27th when compared to the area size of all other countries in the world.
One of the most commonly referred and interesting Biomes in the world is the Desert. Located all throughout the world in arid regions, they cover over 18 million square kilometers. Deserts comprise of about 30% of Earth’s attainable land surface making it one of the largest accessible Biomes in the world. Most of the great deserts are centered on latitudes between 20 and 30 degrees North and South of the Equator, but also may be accessed where large mountain ranges produce intense rain shadows. One of the most commonly referred and greatest deserts is The Sahara located in North Africa stretching over an astounding 9 million square kilometers.
Europe is the second smallest continent on Earth and extends from Iceland (west) to Russia (east), and from Norway (north) to islands of Greece (south). The most distinctive feature of Europe is the diverse landscape. While geological changes that occurred over millions of years have enriched the geological and biodiverse system of the continent, the human interaction with nature over the centuries from emigration to vegetation, industrialization, and urbanization has continued to form a contrasting pattern of physiographic regions in Europe. While there are vast areas with no human presence, much of the diversity of the continent is attributed to the socio-economic and cultural affiliations that are distinctive and localized to geographical
Fluvioglacial Landforms landforms deposited by meltwater from glaciers. some found within the glacier and some under the glacier. outwash plains- composed of sand, gravel and clay (from snout). deposited during times of inc. ablation (glacial retreat).
The Namib Desert The Namib Desert is a parched and rippled desert, an endless expanse. It stretches along the southwest coast of Africa from Angola in the north. through Namibia, into South Africa. The name Namib means “emptiness.”
The Sahara Desert is the world’s largest desert area. The word Sahara comes from the Arabic word sahra’, meaning desert. It extends from the Africa’s Atlantic Ocean side to the Red Sea and consists of the countries of Morocco, Algeria, Tunisia, Libya, Egypt, Mauritania, Mali, Niger, Chad, and Sudan. It is about 5,200 miles long. Overall, the Sahara Desert covers 3,500,000 square miles. The geography of the desert is varied. In the west, the Sahara is rocky with varied elevation. It does contain underground rivers, which sometime penetrate the surface, resulting in oases. The central region of the Sahara has more elevation than the other areas, with peaks such as Emi Koussi and Tahat. Even though the area lacks rainfall, these peaks are snowcapped during the winter. The Eastern part of the Sahara, the Libyan Desert, is dry with very few oases.