1. Patterns and Processes
LANDFORMS
Patterns and Processes

2. Topography
Topography is a general term referring to the surface features of the earth like hills, mountains, valleys and other relief features.

3. Topography
Topography refers to the physical / landform features of the earths surface.
Mt Everest is 8848 m above sea level. The Marianas Trench is 11,034 below sea level. Topography is all the features in between.

4. Topography

5. Hills vs. Mountains Hills elevation < 300 -600m
Mountains elevation > m

6. Plains vs. Plateaus
Both are similar in that they are gently sloping or relatively broad flat regions of land.
Like hills and mountains, plains & plateaus differ based on elevation.
Plains occur at low elevations along coasts & central continent
Plateaus occur at high altitudes and are associated with mountains.

7. Structure
From the surface, the Earth is a planet of continents and oceans.
There is constant motion on the earth’s surface.
Seismology is the study of earthquakes. Scientists use seismology to see into the interior of the Earth.

8. The Earth’s Interior
Crust (Lithosphere)
Mantle
Outer Core
Inner Core

9. Inner Core
The deepest part of the earth (1512 miles deep) is a solid that contains both iron and nickel.
It is because of this that the center of the earth is a magnet, a compass.
It generates a magnetic field that protects the earth from flying out of orbit.

10. Outer Core
Outside of the inner core lays the outer core ( miles deep).
This is much like the inner core with the exception that it is a liquid that contains sulphur and oxygen (which lowers the melting point).

11. Mantle
Occupying 1789 miles of the earth is the magma (iron and magnesium) that makes up the mantle.
Upper and lower
It is extremely hot!!
goopy; very plastic-like. (upper mantle)
Mostly solid (lower mantle)

12. Crust Also called lithosphere
This is the top layer of the earth, which is basically hardened mantle (magma).
It contains two segments, the oceanic and continental crusts.
Note: this is the same crust, it just depends how thick it is to determine if it is part of the Oceanic or Continental Crust.

13. Pangaea "all the earth"
In 1915, the German geologist and meteorologist Alfred Wegener ( ) first proposed the theory of continental drift, which states that parts of the Earth's crust slowly drift atop a liquid core.

14. While pondering the similarities between the coastlines of South America and Africa, Wegener came up with an idea:
What if the continents were once all connected and just drifted over the years?

15. Wegener hypothesized that there was an original, gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth". Pangaea was a supercontinent consisting of all of Earth's land masses.

16. Wegener’s evidence for Continental drift
Ferns and Reptiles in many different continents
Glaciers that were then tropical forests
Same types of rocks on continents close to each other (yet separated by an ocean)
The coastlines of Africa and South America

17. Pangaea started to break up into two smaller supercontinents, called Laurasia and Gondwanaland

20. Plate Tectonics
PLATE TECTONICS The theory of plate tectonics (meaning "plate structure") was developed in the 1960's. This theory explains the movement of the Earth's and also explains the cause of earthquakes, volcanoes, oceanic trenches, mountain range formation, and many other geologic phenomenon.

21. The plates are moving at a speed that has been estimated at 1 to 10 cm per year. Most of the Earth's seismic activity (volcanoes and earthquakes) occurs at the plate boundaries as they interact.

22. Plate Tectonics
Tectonic plates move or float on top of the upper mantle.
However they do not float freely.
The plates are forced in specific directions by the flow of magma beneath.

23. Plate Tectonics
Tectonic plates move or float on top of the upper mantle.
However they do not float freely.
The plates are forced in specific directions by the flow of magma beneath.

24. Plate Tectonics – Convection Currents

25. <------- tensional----------->
Divergent Boundaries
< tensional >
Tensional Forces occur where two tectonic plates are pushed (pulling) apart. The tension is created as the plates move away from each other.
Ridge Zones sometimes occur where two plates move apart. The magma rises between the plates and forms a ridge.

26. Tensional Forces – Ridge Zones
This diagram above shows “Sea Floor Spreading”

27. Where’s the TENSION?

28. Convergent Boundaries
 ----> compressional <------
Compressional Forces occur where two tectonic plates come together. They compress against each other which causes rock layers to bend, warp, or be pushed upwards.
Subduction Zones sometimes occur where compressional forces result from two plates colliding and one plate slips under the other.

29. Divergent or convergent?

30. Compressional Forces – Subduction

31. Where’s the Subduction / Compression?

33. Formation of the Himalaya Mountains

35. Fold Mountains

36. Fold Mountains Most Major Mountain ranges were formed by folding.
The collision of continental plates causes the thin crust (lithosphere) to bend.
For example the Appalachian mountains and the atlas mountains were formed by folding when North America and Africa collided 400 million years ago.
cdli.ca

39. All rock that is put under extreme pressure for long periods of time (thousands or millions of years) will fold like clay.
Folding is a process in which the Earth's plates are pushed together in a roller coaster like series of high points and low points.
Folding bends many layers of rocks without breaking them Anticlines are folds in rocks that bend upwards. Synclines are folds in rocks that bend downwards. Joints are parallel cracks in rocks.

40. An anticline is a convex up fold in rock that resembles an arch like structure with the rock beds (or limbs) dipping way from the center of the structure

41. A syncline is a fold where the rock layers are warped downward
A syncline is a fold where the rock layers are warped downward. Both anticlines and synclines are the result of compressional stress.

42. Picture of Syncline fold in Quebec

43. Mountain Building
Folding
Faulting
Volcanoes

44. Most Major Mountain ranges were formed by the collision of continental Plates

45. Mountains by Folding
Fold mountains are actually formed by crust which have been uplifted and folded (buckled or bent) by compressional forces.
Rock that is put under extreme pressure for long periods of time (thousands or millions of years) will fold like clay.

46. Mountains by Folding…cont’d
Alps
Himilayas
Appalachian
Andes

47. Folding Folding bends many layers of rocks without breaking them.
Often creating a series of peaks and valleys.
Anticline = Peak created by folding
Syncline = Valley creating by folding
Folding
Syncline
Anticline

48. Mountains by Faulting Fault lines are cracks in the crust.
Generally caused by tensional Forces
Land moves apart at Faults.
Hanging Wall drops below the Foot Wall.
This is called a NORMAL FAULT

49. Normal Faults occur when tensional forces act in opposite directions and cause one slab of the rock to be displaced up and the other slab down.

50. Mountains by Faulting Normal Faults
Hanging Wall
Foot Wall

51. Rift Valleys
Sometimes form when many layers of the Earth's crust are moved vertically downward.
Between two parallel fault lines.
Occurs when the broken plate between 2 parallel faults drop as the broken plates move away from each other
P. 14/15

52. Fault Block Mountains
Sometimes form when many layers of the Earth's crust are moved vertically upward.
Generally between two parallel fault lines.
Vertical force is caused by the earth's internal pressure.
The mountains that are formed in this way are called fault-block mountains.
P. 14/15

53. Block Mountains by Faulting

54. Reverse Faults Caused By Compressional Forces (push)
Land moves together at Fault.
Footwall plate is forced under or below the hanging wall.
Hanging wall may rise enough to form a mountain

55. Reverse Faults develop when compressional forces exist
Reverse Faults develop when compressional forces exist. Compression causes one block to be pushed up and over the other block.

56. Reverse Faults – Plate below

57. Reverse Faults-Plate under
Foot Wall
Hanging Wall
Compression Forces

58. Overthrust Fault Folding occurs before being forced under
Caused By Compressional Forces
Land moves together at Fault.
Foot wall plate is forced under the hanging wall.
Plates may have undergone considerable folding prior to overthrusting
Folding occurs
before being
forced under

59. Tension or Compression??
Convergent plates
Subduction zones
Rift Valleys
Mountains by folding
Mountains due to normal fault
Sea Floor Spreading
Mountains due to reverse fault. C T

60. Tension or Compression?- cont’d
Mountains by subduction (2 cont. plates)
Ridge zones, particularly ocean plates
Divergent plates
Fault Block Mountains
Mountains due to overthrust fault
Trenches due to subduction C T

61. COMPRESSION FORCES – Recap!!
Convergent plates – push together
Subduction zones – plate pushed under
Mountains by folding – bending/buckle
Mountains by subduction (2 cont. plates)
Mountains due to reverse fault.
Mountains due to overthrust fault.
Trenches due to subduction {diagram 1.9, p. 11}
Volcanic Mountains by subduction (continental and ocean plate) {diagram 1.9, p. 11}

62. TENSION FORCES – Recap!! Divergent plates
Ridge zones, particularly ocean plates
Mountains due to normal fault
Rift Valleys
Block Mountains
Sea Floor Spreading

63. Mountain Building
Volcanoes

64. What are Volcanoes?
volcanoes are built by the accumulation of their own eruptive products:
lava, bombs (crusted over ash flows), and tephra (airborne ash and dust).
A volcano is most commonly a conical hill or mountain built around a vent that connects with reservoirs of molten rock below the surface of the Earth.

65. What causes them to erupt?
Driven by buoyancy and gas pressure…
molten rock, which is lighter than the surrounding solid rock, forces its way upward…
and may ultimately break though zones of weaknesses in the Earth's crust.
If so, an eruption begins:
The molten rock may pour from the vent as non-explosive lava flows…
Or if may shoot violently into the air as dense clouds of lava fragments.
Molten rock below the surface of the Earth that rises in volcanic vents is known as magma.
After it erupts from a volcano it is called lava.

66. 3 types of volcanoes
Ash and cinder cone
Shield cone
Composite cone

67. Ash & Cinder Cones
They are built from particles and blobs of congealed lava ejected from a single vent.
As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone.
Most cinder cones have a bowl-shaped crater at the summit and rarely rise more than a thousand feet or so above their surroundings.
Cinder cones are numerous in western North America as well as throughout other volcanic terrains of the world.

68. Ash & Cinder Cones Cone shaped Symmetrical Steep sides
Violent eruptions
Layers of ash & Cinder
Single central Vent
Crater at Summit

69. Ash & Cinder Cones

70. Shield Cones
Shield volcanoes are built almost entirely of fluid lava flows.
Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior's shield.
They are built up slowly by the accretion of thousands of highly fluid lava flows called basalt lava that spread widely over great distances, and then cool as thin, gently dipping sheets.

71. Shield Cones Shield - shaped Flat, Shallow sides
Non-Violent slow emissions of lava
Layers of lava
No one single vent
Covers Large area

72. Shield Cones

73. Composite Cones
The essential feature of a composite volcano is a conduit system through which magma from a reservoir deep in the Earth's crust rises to the surface.
The volcano is built up by the accumulation of material erupted through the conduit and increases in size as lava, cinders, ash, etc., are added to its slopes.

74. Composite Cones Shape not as steep as ash & cinder
Non-Violent slow emissions of lava one time and violent ash eruptions next time
Layers of alternating lava & Ash/cinder
Weak sections may form in the side of the cone.
Lava flows out of these forming smaller cones

75. Composite Cones

76. MUST READ!!!
Textbook P
Volcanoes

77. Pacific Ring of Fire Volcanoes occur all around the Pacific ocean.
At the tectonic plate boundaries.
Pattern known as the Pacific Ring of Fire
Activity-Unit1 Handout
Tectonic plate video

78. Pacific Ring of Fire