1. LANDSCAPE DEVELOPMENT
Grotzinger • Jordan
Understanding Earth
Sixth Edition
Chapter 22:
LANDSCAPE DEVELOPMENT
© 2011 by W. H. Freeman and Company

2. Landscape Development
Chapter 22
Landscape
Development

3. About Landscapes
Geomorphology is the study of landscapes and their evolution.
Landscapes are the result of a competition between forces that raise the land surface and those that reduce it.
Landscapes represent a balance between tectonic and climatic systems.

4. Lecture Outline Topography, elevation, and relief
2. Landforms: features sculpted by erosion and sedimentation
3. Interacting geosystems control landscapes
4. Models of landscape development

5. Topography, Elevation, and Relief
● Topography – configuration of
the Earth’s surface
● Elevation – vertical distance
above or below sea level
● Relief – difference in highest
and lowest elevations

6. ● Topographic map – shows the configuration of the Earth’s
1. Topography, Elevation, and Relief
● Topographic map – shows the
configuration of the Earth’s
surface using contours
● Contours – lines that connect
points of equal elevation

7. 1. Topography, Elevation, and Relief: Example – A Mountain Peak in Maine

8. 1. Topography, Elevation, and Relief:
Example – A River Valley in Wyoming

9. 1. Topography, Elevation, and Relief:
Digital Elevation Model of Topography

10. 1. Topography, Elevation, and Relief:
Regional Slope Map

11. 1. Topography, Elevation, and Relief: Various Concepts of Relief

12. ● rugged mountain slopes ● river floodplains ● desert dunes
2. Landforms: Features Sculpted
by Erosion and Sedimentation
● Landforms: examples
● rugged mountain slopes
● river floodplains
● desert dunes

13. ● elevated masses of rock ● to be a mountain, several
2. Landforms: Features Sculpted
by Erosion and Sedimentation
● Mountains and hills
● elevated masses of rock
● to be a mountain, several
100 m of relief is required
● steepness and relief are
usually related

14. Landscape with High Relief
2. Landforms:
Landscape with High Relief

15. ● Flat-topped landforms ● plateaus ● mesas ● tablelands
2. Landforms: Features Sculpted
by Erosion and Sedimentation
● Flat-topped landforms
● plateaus
● mesas
● tablelands

16. 2. Landforms:
Landscape with Mesas
Monument Valley, Arizona

17. Landscape with Sharp Peaks
2. Landforms:
Landscape with Sharp Peaks
southern Argentina

18. 2. Landforms: Features Sculpted by Erosion and Sedimentation
● Structurally controlled ridges and
valleys
● folded mountains
● River valleys and bedrock erosion
● fluvial erosion

19. Landscape with Folded Mountains
2. Landforms:
Landscape with Folded Mountains

20. Development of Ridges and Valleys
2. Landforms:
Development of Ridges and Valleys
Tributary
stream
Resistant
layers
Anticline
Soft
layers
Syncline
Syncline
Main valley stream

21. TIME 1
Tributary streams erode the slopes faster than main streams erode the valleys.
Tributary
stream
Resistant
layers
Anticline
Soft
layers
Syncline
Syncline
Main valley stream

22. Development of Ridges and Valleys
2. Landforms:
Development of Ridges and Valleys
Resistant
layers
Anticline
Soft
layers
Syncline
Syncline

23. TIME 2
Tributaries over the synclines cut through resistant rock layers and start to carve steep valleys over the anticlines.
Resistant
layers
Anticline
Soft
layers
Syncline
Syncline

24. Development of Ridges and Valleys
2. Landforms:
Development of Ridges and Valleys
Resistant
layers
Soft
layers
Syncline
Anticline
Syncline

25. TIME 3
Valleys form over the anticlines and ridges capped by resistant strata are left over the synclines.
Resistant
layers
Soft
layers
Syncline
Anticline
Syncline

26. Example of Ridges and Valleys
2. Landforms:
Example of Ridges and Valleys

28. ● Key processes in fluvial erosion ● abrasion by saltation
2. Landforms: Features Sculpted by Erosion and Sedimentation
● Key processes in fluvial erosion
● abrasion by saltation
● drag force (plucking)

29. The Balance Between Forces
2. Landforms:
The Balance Between Forces
Resistance to
Erosional forces
Erosional forces
Increasing
deposition
Increasing
erosion
Resisting power
Stream power
Sediment size X
Sediment volume
River slope X
River discharge
Equals

30. Increasing sediment size, sediment volume, and bedrock hardness increase the resistance to erosion.
Erosional forces
Erosional forces
Increasing
deposition
Increasing
erosion
Resisting power
Stream power
Sediment size X
Sediment volume
River slope X
River discharge
Equals

31. Increasing river slope and river discharge increase stream power.
Resistance to
Erosional forces
Erosional forces
Increasing
deposition
Increasing
erosion
Resisting power
Stream power
Sediment size X
Sediment volume
River slope X
River discharge
Equals

32. River Erosion in Humid, Steep Areas
2. Landforms:
River Erosion in Humid, Steep Areas

33. In steep, wet terrain, stream power overcomes resistance to erosion
In steep, wet terrain, stream power overcomes resistance to erosion. Bedrock hardness becomes the principal factor in resistance to erosion.

34. River Erosion in Humid, Steep Areas
2. Landforms:
River Erosion in Humid, Steep Areas
Yellowstone River, Wyoming

35. River Erosion Where Forces Balance
2. Landforms:
River Erosion Where Forces Balance

36. Where slopes are gentler, sediment begins to be deposited
Where slopes are gentler, sediment begins to be deposited. Stream power and resistance to erosion are in balance.

37. River Erosion Where Forces Balance
2. Landforms:
River Erosion Where Forces Balance
Snake River, Idaho

38. River Erosion in Flat, Low Areas
2. Landforms:
River Erosion in Flat, Low Areas

39. Where slopes are much flatter, the streambed builds up and fills the valley with sediment.

40. River Erosion in Flat, Low Areas
2. Landforms:
River Erosion in Flat, Low Areas
Mulchatna River, Alaska

41. ● Key factors in fluvial erosion ● stream power ● slope and discharge
2. Landforms: Features Sculpted by Erosion and Sedimentation
● Key factors in fluvial erosion
● stream power
● slope and discharge
● First stages in fluvial erosion
● gullies and badlands

42. Formation of Gullies (Badlands)
2. Landforms:
Formation of Gullies (Badlands)
Badlands National Park, South Dakota

43. ● Structurally controlled cliffs ● cuestas ● hogbacks
2. Landforms: Features Sculpted by Erosion and Sedimentation
● Structurally controlled cliffs
● cuestas
● hogbacks

44. 2. Landforms: Formation of a Cuesta Erosion-resistant sandstone
Easily eroded shale

45. Erosion of weak shale undercuts sandstone.
Erosion-resistant
sandstone
Easily eroded shale

46. 2. Landforms: Formation of a Cuesta
Dinosaur National Monument, Colorado

47. 2. Landforms:
Hogback Ridges
near Roxborough, Colorado

48. 3. Interacting Geosystems
Control Landscapes
● Feedback between uplift and erosion
● negative-feedback process
● process slows when the
driving forces diminish

49. 3. Interacting Geosystems: Example of Negative Feedback

50. 3. Interacting Geosystems Control Landscapes
● Feedback between uplift and erosion
● positive-feedback process
● isostasy and isostatic
rebound

51. 3. Interacting Geosystems: Example of Positive Feedback

52. 3. Interacting Geosystems Control Landscapes
● Feedback between tectonics and
climate
● high elevations enhance
weathering
● low elevations slow down

53. 3. Interacting Geosystems: Plate Tectonics and Climate

54. Thought questions for this chapter
If you were to climb 1 km from a river valley to a mountaintop 2 km high in a tectonically active area versus a tectonically inactive area, which would probably be the more rugged climb?
Describe the main landforms in a low-lying, humid region where the bedrock is limestone.

55. ● Some long-standing concepts ● Davis: cycle of uplift and erosion
4. Models of Landscape Development
● Some long-standing concepts
● Davis: cycle of uplift and erosion
● Penck: erosion competes with
uplift (supported by recent work)
● Hack: over time, landscapes
achieve dynamic equilibrium

56. 4. Models of Landscape Development: Davis’ Cycle of Uplift and Erosion

57. Penck’s Erosion Competes with Uplift
4. Models of Landscape Development:
Penck’s Erosion Competes with Uplift

58. 4. Models of Landscape Development: Hack’s Dynamic Equilibrium

59. ● Some methods of dating landscapes ● Radioisotopic: carbon-14, etc.
4. Models of Landscape Development
● Some methods of dating landscapes
● Radioisotopic: carbon-14, etc.
● Cosmogenic: chlorine-36, etc.
● Chemical: tephrochronology
● Paleomagnetic: reversals, etc.
● Biological: dendrochronology

61. Thought questions for this chapter
The summits of two mountain ranges lie at different elevations: range A at about 8 km and range B at about 2 km. Without knowing anything else about these ranges, could you make an intelligent guess about the relative ages of the mountain-building process that formed them?
A young mountain range of uniform age, rock type, and structure extends from a far northern frigid climate through a temperate zone to a southern tropical rainy climate. How would the topography of the mountain range differ in each of the three climates?

62. Key terms and concepts Contour Cuesta Elevation Geomorphology Hogback
Badland
Contour
Cuesta
Elevation
Geomorphology
Hogback
Landform
Mesa
Plateau
Relief
Stream power
Topography