mass wasting
The downslope movement of the rock and the regolith (loose sediments materials that are eroded and deposited) mainly due to the gravity of the earth is known as mass wasting. Mass wasting erodes the soil and the other materials from the higher elevation to the lower elevation. The factors that change the potential of the mass wasting includes the change in slope angle, the weakening of the material by weathering, increased water content, changes in vegetation cover and overloading.
Summary
The downslope movement of the rock and the regolith (loose sediments materials that are eroded and deposited) mainly due to the gravity of the earth is known as mass wasting. Mass wasting erodes the soil and the other materials from the higher elevation to the lower elevation. The factors that change the potential of the mass wasting includes the change in slope angle, the weakening of the material by weathering, increased water content, changes in vegetation cover and overloading.
Things to Remember
- The geomorphic process by which the soil, regolith, and the rock move down the slope under the force of the gravity.
- A landslide can be distinguished from the landslide in the way of movement and the velocity of the land mass.
- Slope failure is a sudden failure of the slope resulting in the transportation of the debris.
- The rotational slides occur on the slopes of homogeneous clay or shale or the soil slopes.The slide movement is more or less rotational about an axis that is parallel to the counter slope.
- The rock fall occurs when a piece of rock on a steep slope become dislodged and falls down from the slope.
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Subjective Questions
Q1:
Write the psychosexual stages of personality development ?
Type: Long Difficulty: Easy
<ul>
<li><strong>Oral (0-1 years of age)</strong><em>:</em>During this stage, the mouth is the pleasure center for development. Freud believed this is why infants are born with a sucking reflex and desire their mother's breast. If a child's oral needs are not met during infancy, he or she may develop negative habits such as nail biting or thumb sucking to meet this basic need.</li>
<li><strong>Anal (1-3 years of age)</strong>: During this stage, toddlers and preschool-aged children begin toexperiment with urine and feces. The control they learn to exert over their bodily functions is manifested in toilet-training. Improper resolution of this stage, such as parents toilet training their children too early, can result in a child who is uptight and overly obsessed with order.</li>
<li><strong>Phallic (3-6 years of age)</strong><em>:</em>During this stage, preschoolers take pleasure in their genitals and, according to Freud, begin to struggle with sexual desires toward the oppositesexparent (boys to mothers and girls to fathers). For boys, this is called the<em>Oedipus complex,</em>involving a boy's desire for his mother and his urge to replace his father who is seen as a rival for the mother’sattention. At the same time, the boy is afraid his father will punish him for his feelings, so he experiences castrationanxiety. The<em>Electra complex,</em>later proposed by Freud’s protégé Carl Jung, involves a girl's desire for her father's attention and wish to take her mother’s place.</li>
<li><strong>Latency (6-12 years of age)</strong><em>:</em>During this stage, sexualinstinctssubside, and children begin to further develop the superego or conscience. Children begin to behave in morally acceptable ways and adopt the values of their parents and other important adults.</li>
<li><strong>Genital (12+ years of age)</strong><em>:</em>During this stage, sexual impulses reemerge. If other stages have been successfully met, adolescents engage inappropriate sexual behavior, which may lead to marriage and childbirth.</li>
</ul>
Q2:
What does Freud theory of personality development means ?
Type: Short Difficulty: Easy
<ul>
<li><strong>Id</strong></li>
</ul>
<p>It is the component of personality, which is present from birth. Id is driven by the pleasure principle which seeks for immediate gratification for desires, wants, and needs. For eg: An increase in hunger or thirst should produce and immediate attempt to eat or drinks.</p>
<ul>
<li><strong>Ego</strong></li>
</ul>
<p>Ego is the component of personality which is driven by the reality principle. Ego ensures that the impulses of Id can be expressed in a socially acceptable ways.</p>
<ul>
<li><strong>Super-ego</strong></li>
</ul>
<p>Super-ego is the component of personality which is driven by moral principle. It has two component: i) Conscience ii) ego ideal. Super-ego provides guidelines for making judgment</p>
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mass wasting
Mass Wasting
The downslope movement of the rock and the regolith (loose sediments materials that are eroded and deposited) mainly due to the gravity of the earth is known as mass wasting. In the other words, it can also be defined as the geomorphic process by which the soil, regolith, and the rock move down the slope under the force of the gravity. Mass wasting erodes the soil and the other materials from the higher elevation to the lower elevation. So it is considered as the important part of the mass wasting. In this process, the transporting agents are the streams and the glaciers which pick up the material and move it to the lower elevation. The mass wasting process occurs mainly on the slopes, where some may act very slowly whereas the other may act suddenly often with the disastrous and the devastating results. When the gravitational force acting on the slope exceeds its resisting force, slope failure or the mass wasting occurs. the slope materials strength and the cohesion and the amount of the internal frictional force between materials help to maintain the slopes stability and are known as the slope's shear strength. Mass wasting in more ways is related to the growing population as the populations expand more and more over the land surface which in return affect the human themselves. A landslide can be distinguished from the landslide in the way of movement and the velocity of the land mass.
The types of mass wasting include slow flowage, rapid flowage, landslide, subsistence, each their own characteristic features and take place over time periods from the seconds to the years. It occurs both in the terrestrial and the submarine slopes and has been observed to the other planets as well like Mars and Venus.
The mass wasting may occur at a very slow rate particularly in the areas that are very dry or those areas that receive sufficient rainfall such that vegetation has stabilized its surface. It may also occur at the very high speed such as in rock slides or the landslides, with the disastrous consequences, with both immediate or the delayed results. E.g resulting from the formation of the landslide dams.
The factors that change the potential of the mass wasting include:
- change in slope angle (slope angle is the steepest angle that the cohesionless slope can maintain without losing its stability)
- the weakening of the material by weathering
- increased water content
- changes in vegetation cover and
- overloading.
Types of the mass wasting process
Broadly it is categorised into following two categories :
a. Slope failure:Slope failure is a sudden failure of the slope resulting in the transportation of the debris (loose natural materials consisting pieces of rocks especially) down a hill by sliding, rolling, falling, or slumping.
b. Sediment flows:In the sediment flows, the debris flows down the hill mixed with the water or the air.
1. Slope failure
The slope failure is the natural hazard that occurs in many parts of the world. The type of slope failure is controlled by the material properties, water content and the foundation strength of that place. The plane, wedge, toppling, rockfall and the rotational are the common slope failure.
a. Plane failure
When the combinations of the discontinuities in the rock mass forms blocks or wedges within the rock which are free to move, then the rock slope undergoes into the plane failure. In this mode of failure, the pattern of the discontinuities may be comprised of a single discontinuity or a pair of discontinuities that intersect each other or a combination of multiple discontinuities that are linked together. When the mass of the rock slides along a planar surface then it results in plane failure. The failure surfaces are usually the structural discontinuities like bedding planes, faults, joints or the interface between bedrock and an overlying layer of weathered rock.
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b. Wedge failure
When the rock mass slides along the two intersecting discontinuities, both of which dip out of the cut slope at an oblique angle to the cut face, forms the wedge-shaped block. Wedge failure may occur in the rock mass with two or more sets of discontinuities when the lines of intersection are approximately perpendicular to the strike of the slope and dip towards the plane of the slope.
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c. Toppling failure
When the columns of the rock, formed by steeply dipping the discontinuities in the rock rotates about an essentially fixed point at or near the base of the slope followed by slippage between the layers, then the toppling failure occurs. The center of gravity of the column or slab must fall outside the dimension of its base in toppling failure. Jointed rock mass closely spaced and steeply dipping discontinuity sets that dip away from the slope surface is necessary prerequisites for toppling failure.
2. Rockfall
The rock fall occurs when a piece of rock on a steep slope become dislodged and falls down from the slope. A rock fall may be single or a mass of rocks and the falling rocks can dislodge the other rocks as they collide with the cliff. As this process involve the free fall of the material, fall generally occurs where there is a steep cliff. The accumulated fallen material at the base of the cliff is known as talus.
3. Slides
Slides generally refer to the mass movement with a distinct surface of rupture, separating the slide material from the more stable underlying materials. Slides can be categorized as:
i. Rotational slide
The rotational slides occur on the slopes of homogeneous clay or shale or the soil slopes. The slide movement is more or less rotational about an axis that is parallel to the counter slope.
ii. Translational slide
This is the mass movement in more or less the planar surface. The movement of the transitional slides is controlled by the surface of weakness such as bedding planes, joints, faults. The slide material may range from the loose unconsolidated soils to the slabs of the rocks.
References
Keller, E.A.Environmental Geology. Columbus, Ohio: Charles E. Miller Publishing Company,Belland Howell Company, 1985.
Mahapatra, G.B.Textbook of Physical Geology. Shahadra,Delhi-110032: CBS Publishers and Distributers Pvt.Ltd., 1992.
Upreti,B.N. and Dhital, M.R.(1996), Landslide Studies and Management in Nepal.ICIMOD, 87p
Lesson
Environmental Earth science
Subject
Environmental science
Grade
Bachelor of Science
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