Mass movements, erosion, and deposition

Q: Downslope movement of material is mainly controlled by which force?

Gravity Gravity pulls material downslope in mass movement. Exam tip: connect it with exogenic geomorphic processes.

Q: Which is the most reliable sign of soil creep?

Slowly tilted poles and bent fences The direct answer is B, slowly tilted poles and bent fences. Soil creep is the extremely slow, gradual downslope movement of loose soil and weathered material under gravity. Because the movement is slow, it may not be noticed from one day to the next. Over months or years, however, objects fixed in the ground slowly lean downhill. This creates tilted poles, bent fences, curved tree trunks, and sometimes small step-like features on a slope. Option A, sudden deep gorge formation, is incorrect because a gorge is mainly produced by strong river erosion, not the slow mass movement called soil creep. Option B is correct because poles and fences record the long-term movement of the soil beneath them. Option C, a mountain collapsing in one day, describes a sudden landslide or collapse, not creep. Option D, a river immediately forming a delta, concerns deposition at a river mouth and is unrelated to slope movement. The reasoning is therefore: soil creep is slow movement, slow movement bends or tilts objects gradually, and tilted poles or bent fences are visible evidence. A useful memory trick is “creep bends, landslide breaks.” In an examination, look for the option showing gradual movement and long-term deformation, not a sudden dramatic event.

Q: What is the basic basis for distinguishing landslide from soil creep?

Speed and suddenness Landslides can be rapid and sudden while soil creep is very slow. Exam tip: treat speed as the main criterion.

Q: Why does water saturation reduce slope stability?

It lowers friction between particles and increases weight Water saturation lowers particle friction and adds weight on slopes. Exam tip: remember water as a major landslide factor.

Q: Under which condition is debris flow most active?

Loose material on steep slopes with sudden heavy rain Debris flow forms from loose material mixed with water on steep slopes. Exam tip: link rainfall with slope.

Q: Rockfall is generally associated with which landform?

Steep rocky slope Rockfall is sudden falling of material from steep jointed rocks. Exam tip: place it under rapid mass movement.

Q: What is the process of downslope movement along a curved surface called?

Slump In slump material moves downward along a curved slip surface. Exam tip: treat it as a specific landslide type.

Q: How does frost action promote mass movement?

It breaks rocks and produces loose material Frost action widens cracks and supplies loose material. Exam tip: see weathering as preparation for mass movement.

Q: In which stage is lateral erosion by a river most dominant?

Mature stage In the mature stage rivers form meanders and lateral erosion increases. Exam tip: link meanders with lateral erosion.

Q: Which process deepens a river bed by grinding?

Abrasion In abrasion the river uses its load to grind bed and banks. Exam tip: remember it as a mechanical erosion process.

01Downslope movement of material is mainly controlled by which force?

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Answer and explanation

Correct answer: A. Gravity

Gravity pulls material downslope in mass movement. Exam tip: connect it with exogenic geomorphic processes.

Practice questions

01Downslope movement of material is mainly controlled by which force?ढाल पर पदार्थ का नीचे की ओर सरकना मुख्यतः किस बल से नियंत्रित होता है?

02Which is the most reliable sign of soil creep?मृदा सर्पण को पहचानने का सबसे विश्वसनीय संकेत कौन सा है?

03What is the basic basis for distinguishing landslide from soil creep?भूस्खलन और मृदा सर्पण में मूल अंतर किस आधार पर किया जाता है?

04Why does water saturation reduce slope stability?जल संतृप्ति ढाल की स्थिरता को क्यों घटाती है?

05Under which condition is debris flow most active?मलवा प्रवाह किस परिस्थिति में सबसे अधिक सक्रिय होता है?

06Rockfall is generally associated with which landform?शैल पतन सामान्यतः किस स्थलाकृति से जुड़ा होता है?

07What is the process of downslope movement along a curved surface called?स्खलन में घुमावदार सतह पर नीचे खिसकने वाली प्रक्रिया को क्या कहा जाता है?

08How does frost action promote mass movement?तुषार क्रिया जन संचलन को कैसे बढ़ाती है?

09In which stage is lateral erosion by a river most dominant?नदी द्वारा पार्श्व अपरदन सबसे अधिक किस अवस्था में प्रमुख होता है?

10Which process deepens a river bed by grinding?नदी के तल में घिसाई द्वारा तल को गहरा करने की प्रक्रिया कौन सी है?

11What is the process in which river particles become smaller and rounded by collision?नदी में कणों के आपसी टकराव से छोटे और गोल बनने की प्रक्रिया क्या कहलाती है?

12How does a river erode rock by hydraulic action?हाइड्रोलिक क्रिया में नदी शैल को कैसे काटती है?

13Solution action is more effective on which type of rocks?घोल क्रिया किस प्रकार की चट्टानों पर अधिक प्रभावी होती है?

14What is the main reason for strong vertical erosion in an upper valley?ऊपरी घाटी में लंबवत अपरदन अधिक होने का मुख्य कारण क्या है?

15A V-shaped valley is mainly the result of which process?वी आकार की घाटी किस प्रक्रिया का प्रमुख परिणाम है?

16The direct relation between erosion and deposition is decided by what?अपरदन और निक्षेपण के बीच सीधा संबंध किस बात से तय होता है?

17Under which condition does a river start depositing its load?किस स्थिति में नदी अपना भार निक्षेपित करने लगती है?

18Which condition is most suitable for delta formation?डेल्टा निर्माण के लिए कौन सी स्थिति सबसे उपयुक्त है?

19A floodplain is formed by which long-term process?बाढ़ मैदान किस दीर्घकालिक प्रक्रिया से बनता है?

21In a meander erosion is mainly greater on which side?मेन्डर में कटाव मुख्यतः किस ओर अधिक होता है?

22Which process is more common on the inner bend of a meander?मेन्डर के भीतरी मोड़ पर कौन सी प्रक्रिया अधिक होती है?

23What is the final stage in the formation of an oxbow lake?ऑक्सबो झील बनने की अंतिम अवस्था क्या होती है?

24What is the effect of base level on river erosion?आधार तल का नदी अपरदन पर क्या प्रभाव है?

25When is marine abrasion strongest?समुद्री तरंगों में अपघर्षण सबसे अधिक कब होता है?

Analytics choices

01Downslope movement of material is mainly controlled by which force?

02Which is the most reliable sign of soil creep?

03What is the basic basis for distinguishing landslide from soil creep?

04Why does water saturation reduce slope stability?

05Under which condition is debris flow most active?

06Rockfall is generally associated with which landform?

07What is the process of downslope movement along a curved surface called?

08How does frost action promote mass movement?

09In which stage is lateral erosion by a river most dominant?

10Which process deepens a river bed by grinding?

11What is the process in which river particles become smaller and rounded by collision?

12How does a river erode rock by hydraulic action?

13Solution action is more effective on which type of rocks?

14What is the main reason for strong vertical erosion in an upper valley?

15A V-shaped valley is mainly the result of which process?

16The direct relation between erosion and deposition is decided by what?

17Under which condition does a river start depositing its load?

18Which condition is most suitable for delta formation?

19A floodplain is formed by which long-term process?

21In a meander erosion is mainly greater on which side?

22Which process is more common on the inner bend of a meander?

23What is the final stage in the formation of an oxbow lake?

24What is the effect of base level on river erosion?

25When is marine abrasion strongest?