geography m2 soil creep

Subject Module #2 Unit #2 Lesson #3

SOIL CREEPSOIL CREEP

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OBJECTIVESOBJECTIVES

What is mass wasting?


Mass Wasting or Soil Erosion?


Classifying Mass Movement


Soil CreepSoil Creep

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INTRODUCTIONINTRODUCTIONThis lesson introduces mass wasting which includes slow movements such as soil creep . Soil creep is explained and evidence of soil creep is also looked at. The factors influencing soil creep and the impact of soil creep are also examined.

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INTRODUCTIONINTRODUCTION1. Explain the term mass wasting (mass

movement)2. Differentiate between mass wasting and soil

erosion3. Classify types of mass movement 4. Describe the factors that contribute to soil

creep5. Draw and label a diagram showing soil creep6. Recognize the signs of soil creep7. Be aware of the impact of soil creep on natural

and man-made features

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INTRODUCTIONINTRODUCTION

Mass movement or mass wasting is used to describe all the down slope movement of weathered material (regolith) due to the force of gravity.

Weathered material is called regolith.

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Mass wasting refers ONLY to the movement of weathered material down slope whereas soil erosion is concerned

with the movement of soil by agents such as wind, ice, water.

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The types of mass movement may be classified according to:

Speed of movement

Amount of moisture (water content)

Type of material being moved

For this lesson mass movement will be classified according the speed of movement.

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INTRODUCTIONINTRODUCTION Rapid movement

Flow movements

Slow movement

Landslide Earth flow Soil creep

Rock fall Mud flow Rock creep

avalanche Solifluction

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INTRODUCTIONINTRODUCTION Soil creep is the slowest of all mass movements. It takes place at a rate of 1-3 mm per year in temperature latitudes and 10 mm per year in tropical forests.

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INTRODUCTIONINTRODUCTION This type of movement is imperceptible and continuous.

This downhill movement of soil takes place on gentle moderately steep slopes.

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TILTED FENCE

BENT TREE TRUNK

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TERRACETTES

Step-like features that develop when vegetation is stretched and torn.

terracette

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INTRODUCTIONINTRODUCTIONGravity -Everywhere on the Earth’s surface the force of gravity exerts a downward pull on all materials, such as soil and loose rocks (weathered material). All the different kinds of mass wasting are due to the force of gravity i.e. all down hill movements are influenced by gravity.

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INTRODUCTIONINTRODUCTION Moisture - water acts as a lubricant aiding movement downhill. Movement is greatest during or immediately following heavy rainfall, especially if rain comes after long dry periods.

Soil creep does not require a lot of moisture, but water does aid in the movement of soil down slope.

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INTRODUCTIONINTRODUCTION Weathered soil – when the soil has been weathered , is poorly consolidated or is disturbed for example by trampling by animals soil creep may occur.

Weathering weakens the soil making susceptible to soil creep, that is soil continuous movement down hill

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INTRODUCTIONINTRODUCTION Slope angle- the degree of steepness will influence the speed down hill movement. Soil creep occurs on gentle to moderate slopes.

Soil creep will not occur on flat land.

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INTRODUCTIONINTRODUCTION Soil creep is a slow down hill movement and therefore it is not as devastating as faster types of mass movement.

However the accumulation of soil behind a fence or a wall can lead to its destruction.

Layers of top soil may be lost and trees left without adequate support.

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INTRODUCTIONINTRODUCTION Are you ready to test yourself? There are five multiple choice items that you

are required to do. For each item, click on the letter of the correct

response and then click the button ‘NEXT QUESTION’ to continue.

Click the BEGIN QUIZ button to proceed.

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BEGIN QUIZ!BEGIN QUIZ!









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INTRODUCTIONINTRODUCTIONAll of the following are classified as rapid types of mass wasting EXCEPT

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A. landslideA. landslide

B. Rock fallB. Rock fall

C. avalancheC. avalanche

D. Soil creepD. Soil creep

FEEDBACKFEEDBACKFEEDBACKFEEDBACK









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INTRODUCTIONINTRODUCTIONQuestion 1: All of the following are classified as rapid types of mass wasting EXCEPT.

FeedbackD. Soil creep

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NEXT NEXT QUESTIONQUESTION










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INTRODUCTIONINTRODUCTIONWhich of the following is evidence of soil creep?

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A. Trees shedding their leavesA. Trees shedding their leaves

D. Animals grazing on a slope D. Animals grazing on a slope

C. Water flowing down hillC. Water flowing down hill

B. Accumulation of soil behind a wallB. Accumulation of soil behind a wall










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INTRODUCTIONINTRODUCTIONQuestion 2: Which of the following is evidence of soil creep?

FeedbackB. Accumulation of soil behind a wall.

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INTRODUCTIONINTRODUCTIONWhich of the following factors does NOT influence soil creep?

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A. GravityA. Gravity

D. Rainfall D. Rainfall

B. Slope angle B. Slope angle

C. Vegetation cover C. Vegetation cover










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INTRODUCTIONINTRODUCTIONQuestion 3: Which of the following factors does NOT influence soil creep?

FeedbackC. Vegetation cover

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INTRODUCTIONINTRODUCTIONWhat is regolith?

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A. Saturated soilA. Saturated soil

D. An invisible forceD. An invisible force

C. Small step-like featuresC. Small step-like features

B. Weathered material B. Weathered material










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INTRODUCTIONINTRODUCTIONQuestion 4: What is regolith?

FeedbackB. Weathered material

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INTRODUCTIONINTRODUCTIONWhat is mass movement?

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B. Removal of weathered material by running water.B. Removal of weathered material by running water.

D. Removal of soil and rock by wind.D. Removal of soil and rock by wind.

C. Downhill movement of soil and rocks due to the force of wind.C. Downhill movement of soil and rocks due to the force of wind.

A. Down hill movement of weathered material due to the force of gravity.A. Down hill movement of weathered material due to the force of gravity.










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INTRODUCTIONINTRODUCTIONQuestion 5: What is mass movement?

FeedbackA. Down hill movement of weathered material due

to the force of gravity.

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