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Weathering And Mass Movement Pdf

weathering and mass movement pdf

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In chapter 5 you read about sink holes, one form of weathering by water and gravity. Sink holes form what is known as Karst Topography , which has the effect of making the landscape appear pockmarked. Karst topography results from the chemical weathering of limestone underground, and the action of gravity forcing the overlying earth to fill in the void.

The crust of the earth is raised or depressed with respect to the geoid by endogene phenomena associated with epeirogeny and orogeny. These large-scale crustal movements come within the province of tectonics and are not considered here. The surface layers of the crust are subject in addition to the action of exogene processes, largely controlled by climate, of which weathering, mass movement and mass transport are the chief. These interact with the endogene processes to produce surface form.

Mass wasting

Mass wasting , also known as slope movement or mass movement , is the geomorphic process by which soil , sand , regolith , and rock move downslope typically as a solid , continuous or discontinuous mass, largely under the force of gravity , frequently with characteristics of a flow as in debris flows and mudflows. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus and Jupiter's moons Io and Ganymede. When the gravitational force acting on a slope exceeds its resisting force, slope failure mass wasting occurs.

The slope material's strength and cohesion and the amount of internal friction within the material help maintain the slope's stability and are known collectively as the slope's shear strength. The steepest angle that a cohesionless slope can maintain without losing its stability is known as its angle of repose.

When a slope made of loose material possesses this angle, its shear strength counterbalances the force of gravity acting upon it.

Mass wasting may occur at a very slow rate, particularly in areas that are very dry or those areas that receive sufficient rainfall such that vegetation has stabilized the surface.

It may also occur at very high speed, such as in rockslides or landslides , with disastrous consequences, both immediate and delayed, e. Factors that change the potential of mass wasting include: change in slope angle, weakening of material by weathering , increased water content; changes in vegetation cover, and overloading.

Volcano flanks can become over-steep resulting in instability and mass wasting. This is now a recognised part of the growth of all active volcanoes. It is seen on submarine volcanoes as well as surface volcanoes: Loihi in the Hawaiian—Emperor seamount chain and Kick 'em Jenny in the Lesser Antilles Volcanic Arc are two submarine volcanoes that are known to undergo mass wasting.

The failure of the northern flank of Mount St Helens in showed how rapidly volcanic flanks can deform and fail. Water can increase or decrease the stability of a slope depending on the amount present. Small amounts of water can strengthen soils because the surface tension of water increases soil cohesion.

This allows the soil to resist erosion better than if it were dry. If too much water is present the water may act to increase the pore pressure, reducing friction, and accelerating the erosion process and resulting in different types of mass wasting i.

A good example of this is to think of a sand castle. Water must be mixed with sand for the castle to keep its shape. If too much water is added the sand washes away, if not enough water is added the sand falls and cannot keep its shape.

Water also increases the mass of the soil, this is important because an increase in mass means that there will be an increase in velocity if mass wasting is triggered. Saturated water, however, eases the process of mass wasting in that the rock and soil debris are easily washed down-slope. Based on how the soil, regolith or rock moves downslope as a whole, mass movements can be broadly classified as creeps and landslides.

Soil creep is a slow and long term mass movement. The combination of small movements of soil or rock in different directions over time is directed by gravity gradually downslope. The steeper the slope, the faster the creep. The creep makes trees and shrubs curve to maintain their perpendicularity, and they can trigger landslides if they lose their root footing. The surface soil can migrate under the influence of cycles of freezing and thawing, or hot and cold temperatures, inching its way towards the bottom of the slope forming terracettes.

Landslides are often preceded by soil creep accompanied with soil sloughing — loose soil that falls and accumulates at the base of the steepest creep sections. A landslide , also called a landslip, is a slow or rapid movement of a large mass of earth and rocks down a hill or a mountainside. Little or no flowage of the materials occurs on a given slope until heavy rain and resultant lubrication by the same rainwater facilitate the movement of the materials, causing a landslide to occur.

In particular, if the main feature of the movement is a slide along a planar or curved surface, the landslide is termed slump , earth slide, debris slide or rock slide, depending on the prevailing material. Movement of soil and regolith that more resembles fluid behaviour is called a flow. These include avalanches , mudflows , debris flows , earth flow , lahars and sturzstroms. Water, air and ice are often involved in enabling fluid-like motion of the material.

A fall, including rockfall and debris fall occurs where regolith cascades down a slope, but is not of sufficient volume or viscosity to behave as a flow. Falls are promoted in rocks which are characterized by the presence of vertical cracks. Falls can also result from undercutting by running water as well as by waves. They usually occur at very steep slopes such as a cliff face. The rock material may be loosened by earthquakes, rain, plant-root wedging and expanding ice, among other things.

The accumulation of rock material that has fallen and resides at the base of the structure is known as talus. Soil and regolith remain on a hillslope only while the gravitational forces are unable to overcome the frictional forces keeping the material in place see slope stability.

Some factors that reduce the frictional resistance relative to the downslope forces, and thus can trigger slope movement, can include:. From Wikipedia, the free encyclopedia. Geomorphic process by which soil, sand, regolith, and rock move downslope. This article includes a list of references , related reading or external links , but its sources remain unclear because it lacks inline citations.

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Sound Native Plants. Retrieved Geotechnical engineering. Offshore geotechnical engineering. Core drill Cone penetration test Geo-electrical sounding Permeability test Load test Static Dynamic Statnamic Pore pressure measurement Piezometer Well Ram sounding Rock control drilling Rotary-pressure sounding Rotary weight sounding Sample series Screw plate test Deformation monitoring Inclinometer Settlement recordings Shear vane test Simple sounding Standard penetration test Total sounding Trial pit Visible bedrock Nuclear densometer test Exploration geophysics Crosshole sonic logging Pile integrity test Wave equation analysis.

Soil classification Atterberg limits California bearing ratio Direct shear test Hydrometer Proctor compaction test R-value Sieve analysis Triaxial shear test Oedometer test Hydraulic conductivity tests Water content tests.

Shallow Deep. Effective stress Pore water pressure Lateral earth pressure Overburden pressure Preconsolidation pressure.

Geologic principles and processes. Principle of original horizontality Law of superposition Principle of lateral continuity Principle of cross-cutting relationships Principle of faunal succession Principle of inclusions and components Walther's law. Fluvial processes Aeolian processes Glacial processes Mass wasting processes. Categories : Environmental soil science Geological hazards Geomorphology.

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Help Learn to edit Community portal Recent changes Upload file. Download as PDF Printable version. Wikimedia Commons. Wikimedia Commons has media related to Mass movements geology.

Field in situ Core drill Cone penetration test Geo-electrical sounding Permeability test Load test Static Dynamic Statnamic Pore pressure measurement Piezometer Well Ram sounding Rock control drilling Rotary-pressure sounding Rotary weight sounding Sample series Screw plate test Deformation monitoring Inclinometer Settlement recordings Shear vane test Simple sounding Standard penetration test Total sounding Trial pit Visible bedrock Nuclear densometer test Exploration geophysics Crosshole sonic logging Pile integrity test Wave equation analysis.

Forces Effective stress Pore water pressure Lateral earth pressure Overburden pressure Preconsolidation pressure.

5.0 Weathering, Soil and Mass Movements Video - YouTube

Mass wasting , also known as slope movement or mass movement , is the geomorphic process by which soil , sand , regolith , and rock move downslope typically as a solid , continuous or discontinuous mass, largely under the force of gravity , frequently with characteristics of a flow as in debris flows and mudflows. Mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus and Jupiter's moons Io and Ganymede. When the gravitational force acting on a slope exceeds its resisting force, slope failure mass wasting occurs. The slope material's strength and cohesion and the amount of internal friction within the material help maintain the slope's stability and are known collectively as the slope's shear strength. The steepest angle that a cohesionless slope can maintain without losing its stability is known as its angle of repose. When a slope made of loose material possesses this angle, its shear strength counterbalances the force of gravity acting upon it.

weathering and mass movement pdf

And, can you mentally image how weathering, mass wasting, and erosion would operated in such diverse landscapes? honeycreekpres.org


9.2: Mass Movement - Weathering by Gravity and Water

Rockfalls and rockslides. Rockfalls occur when pieces of rock break loose from a steep rock face or cliff. These result from the rock face being undercut by rivers or wave action. Frost wedging may also eventually loosen large blocks, causing them to fall. The accumulation of rock debris at the base of a steep slope is called talus.

Mass wasting is the movement of rock and soil down slope under the influence of gravity. Rock falls, slumps, and debris flows are all examples of mass wasting. Often lubricated by rainfall or agitated by seismic activity, these events may occur very rapidly and move as a flow. Landslide triggers may include:.

Geomorphic models of slope development and hydrologic models of runoff generation are reviewed in order to identify the major processes of interest. Slope erosion and mass movement are then classified and typical rates of operation identified.

Another way material can be moved on the coastline is through mass movement. Mass movement is the downhill movement of sediment that moves because of gravity. There are four different types of mass movement:. Bits of rock fall off the cliff face, usually due to freeze-thaw weathering. Saturated soil soil filled with water flows down a slope.

 Я все рассказал лейтенанту. - Я с ним говорил, но… - Надеюсь, вы отчитали его как следует! - воскликнул Клушар. Беккер кивнул: - Самым решительным образом. Консульство этого так не оставит. - Надеюсь.

Хейл упал на колени, не опуская рук. - Ах ты, мерзавка! - крикнул он, скорчившись от боли. Сьюзан бросилась к двери, моля Бога, чтобы Стратмор в этот миг включил резервное энергоснабжение и дверь открылась.

1 Comments

  1. Paddy B.

    02.05.2021 at 20:36
    Reply

    Weathering and mass wasting work relentlessly to shape Earth's surface. • The deeply scarred walls of valleys are evidence of their tremendous potential for.

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