Slops

Slops, Mass movement, Pediment, Badland,

1. Slopes Desert Geomorphology

2. Slopes Padiments lnselbergs Mass movement Badlands

3. Slopes What is Slopes ? Slope Process Types of Slopes Slope Elements

4. What is Slopes ? The angle which any part of the Earth’s surface makes with the horizontal. vertical change horizontal change

5. Slopes process Geological agents water ice wind + Gravity’s Role Erosion (weathering) Transportation ( mass movement ) Deposition ( Debris slop, Talus cone)

6. Types of Slopes 1-Gentle Slopes 2-Steep Slope 3-Convex Slope 4-Concave Slope 5-Depositional Slopes 6-Tectonic Slopes

7. Types of Slopes What is the Different between Gentel Slope and Steep Slope? topographical map

8. Types of Slopes Gentle Slope A slope with contour lines spread far apart from each other. This even spacing is maintained in both up and down slope. 2. Steep Slope A slope represented with contour lines close to each other on a topographical map. topographical map

9. Types of Slopes 3- Convex Slope 4- Concave Slope A slope which becomes progressively steeper downhill A slope which becomes progressively steeper uphill

10. 5- Depositional Slopes Deposits of weather material build up to form inclined surfaces, mounds and hills when an agent of erosion (e.g. wind, water or ice) Types of Slopes Examples - alluvial fans alluvial cones deltas -sand dunes.

11. 6-Tectonic Slopes These are formed through ”internal forces“ that result in the ) folding, warping and faulting( of rock masses or layers. Anticlines and synclines horsts and graben Types of Slopes

12. Slope Elements Crest A small convex-shaped slope, with a thin covering of soil Scarp Cliff A near vertical slope, more than 80° to the horizontal Talus / Scree / Debris A slope with a constant angle, and is formed of eroded material from crest and freeface Knickpoint The change in gradient at the base of the scree slope Pediment A low-angle concave slope

13. Knickpoint

14. Padiments What is pediments? Processes responsible for carving pediments Formational zones of pediments

15. What is pediments? A pediment is a very gently sloping (5°-7°) It typically slopes down from the base of a steeper retreatin g desert cliff , or escarpment , but may continue to exist after the mountain has eroded away . It is caused by erosion .

16. What is pediments? It develops when sheets of running water wash over it in intense rainfall events.

17. Three formational zones are recognized for pediments: • An inner most zone of mountainous uplands that have near vertical erosion • An intermediate zone which is the pediment beyond the mountain front. • An outer zone which extends beyond the pediment and is a zone of deposition. Coalescence of pediments over a large area results in a pediplain . formational zones of pediments

18. Processes responsible for carving pediments • Erosion by a stream. • Sheet erosion "The removal of thin layers of surface material more or less evenly from an extensive area of gently sloping land, by broad continuous sheets of running water rather than by stream flowing in well defined channels

19. • Rill erosion "The development of numerous minute closely spaced channels resulting from the uneven removal of surface soil by running water that is concentrate in streamlets of sufficient discharge and velocity to generate cutting power ” • Mountain-front retreating by weathering Processes responsible for carving pediments

20. Inselbergs What is Inselbergs? Example

21. A small, rounded hill, knob, ridge, or mini mountain that rises abruptly from relatively flat surroundings. Inselbergs are generally erosional remnants. Often, inselbergs are composed of harder igneous rock (such as granite)that is more resistant to erosion. What is Inselbergs?

22. Example Uluru or Ayer's Rock inselberg in Australia. Photo courtesy of Gillian. Steep-sided monument. Western USA, Fall 2005.

23. Mass movement What is Mass movement? The importance of Water in mass movement Types of mass movement Triggers of mass movement

24. What is Mass movement?

25. What is Mass movement? “ is the movement of surface material caused by gravity. Landslides and rockfalls are examples of very sudden movements of this type” Geological agents water ice wind + Gravity’s Role

26. • The mass must overcome: – Friction- resistance to motion of a body thatkeeps it from moving over another body. – Inertia- tendency of a body to remain at rest until external force is applied Geological agents water ice wind + Gravity’s Role What is Mass movement?

27. 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 between material help maintain the slope's stability and are known collectively as the slope's shear strength . Gravity’s Role

28. The steepest angle that a cohesionless slope can maintain without losing its stability is known as its angle of repose . Angle of repose

29. The importance of Water in mass movement 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.e. mudflows, landslides, etc.)

30. Types of mass movement

31. Soil Creep Creep is the slow, continuous movement of soil or unconsolidated sediments over extended periods of time. Causes of Soil Creep Creep is caused by repeated freeze-thaw cycles that slowly inch material downslope (during freezing, particles are elevated perpendicular to the slope, but during thaws they fall straight down to a new position lower on the slope). Creep can also be caused by a buildup of pore water that allows material to begin to flow under the influence of gravity. Effects of Soil Creep Creep causes fence posts, utility poles, walls, and other structures to lean over time. Eventually the lean topples the structures and they must be rebuilt. In some cases, creep can be slowed or prevented by installing drainage pipes in soils that drain them and keep pore pressures low.

32. Solifluction It is the down slope movement of soil over a permanently frozen subsurface. Solifluction is common on slopes underlain by permafrost (permanently frozen sub – soil).

33. Landslides A landslide is a movement of rock or debris down a slope along one or more distinct surfaces. Landslides range in speed from 1 m/day to as much as 300 km/hr.

34. Rockfalls Rockfall (free fall of rock) is an extremely rapid process and occurs without warning. Rockfall is typically the result of frost wedging.

35. A mudflow or mud flow : is a form of mass wasting involving "very rapid to extremely rapid surging flow"of debris that has become partially or fully liquified by the addition of significant amounts of water to the source material .

36. Slumps The sliding of material along a curved surface called a rotational slide or slump. A common cause of slumping is erosion at the base of a slope. For example, coastal storm waves erode cliff bases, removing supporting material. The slump block rotates downward, producing a scarp (cliff) at the top of the slope.

37. Triggers of mass movement Soil and regolith remain on a hillslope only while the gravitational forces are unable to overcome the frictional forces keeping the material in place . Factors that reduce the frictional resistance relative to the downslope forces, and thus initiate slope movement, can include: earthquakes increased overburden from structures increased soil moisture reduction of roots holding the soil to bedrock undercutting of the slope by excavation or erosion weathering by frost heave bioturbation

38. Badlands What is Badlands ? Composition Formation Example

39. Whats is badlands ? Badlands are a type of dry terrain where softer sedimentary rocks and clay -rich soils have been eroded by wind and water. Steep Slopes Minimal Vegetation lack of a substantial regolith high drainage density.

40. They can resemble a terrain of volcanic rock , Canyons , ravines , gullies , buttes , mesas , hoodoos and other such geologic forms are common in badlands. They are often difficult to navigate by foot. Badlands often have a spectacular color display from dark black/blue coal stria to bright clays to red scoria.

41. Composition Badlands are characterized by their thin to nonexistent regolith layers. The regolith profiles of badlands in arid climates are likely to resemble one another the upper layer (~1–5 cm) is typically composed of silt, shale, and sand The top layer is a sublayer (~5–10 cm), below which can be found a transitional shard layer (~10–40 cm), formed largely of loose disaggregated shale chips

42. Formation The process of deposition describes the accumulation, over time, of layers of mineral material. Different environments. ( such as seas, rivers, or tropical zones, deposit different sorts of clays, silts, and sand.) 47-million year period of deposition which spanned three major geologic periods deposition Erosion. National Park, South Dakota, United States

43. Example The "Calanchi" of Aliano, in the Italian region of Basilicata

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