1. MOUNTAIN BUILDING

2. Rock Deformation and Mountain Building
The process of forming a mountain not only uplifts the surface of the Earth, it causes rocks to undergo Deformation.
Rock deformation refers to changes in the shape, volume, or orientation of a rock due to changes in temperature and pressure over time.

3. Deformation – The breaking, tilting, and folding of crustal rock due to crustal movement. (three types of forces)
1. Compression – squeezing of earth’s crust that compacts the rock. Convergent boundary
2. Tension – is the pulling apart of the earth’s crust. Divergent boundary.
3. Shearing – pushes rocks side by side in opposite directions. Transform boundary.

4. Rock Deformation and Mountain Building
In general it can be that a rock has been deformed if it has: – translated (moved) from its original position – changed in orientation (folding, rotation and/or tilting) – changed in shape (distortion)

5. What are two kinds of folds?
Folding occurs when rock layers bend under stress. The bends are called folds.
Scientists assume that all rock layers start out as horizontal layers deposited on top of each other over time.
A fold, or bend, in the rock layers means that deformation has happened.
Two common types of folds are synclines and anticlines.
In a syncline, the youngest layers of rock are at the core of the fold. The rock layers are usually arched downward, like a bowl.
In an anticline, the oldest layers of rock are at the core of the fold. The rock layers are usually arched upward.

6. Synclines and Anticlines
These two types of folds are most often found in adjacent to one another.
Both are examples of ductile deformation.
Both are commonly due to horizontal compressional stress.

8. Anticline
Syncline: See the smile?

9. Syncline, anticline, syncline (the right syncline is cut by a vertical fault)

10. What are two kinds of folds?
Identify the oldest and youngest rock layers in this diagram.
Oldest Rock Layers

11. What are the three kinds of faults?
Sometimes rock is under so much stress that it breaks.
A crack called a fault forms when large blocks of rock break and move past each other.
The blocks of rock on either side of a fault are called fault blocks. The movement of faults can create mountains and other landforms.

12. What are the three kinds of faults?
Fault Plane
The three main kinds of faults are
1. normal faults,
2. reverse faults, and
3. strike-slip faults.
A fault plane is the location where two fault blocks meet.

13. What are the three kinds of faults?
In a normal fault, the hanging wall moves down relative to the footwall, in a way you would normally expect as a result of gravity.
Normal faults form when rock is under tension, which is stress that stretches or pulls rock apart.
Normal faults are common along divergent boundaries.

15. What are the three kinds of faults?
In a reverse fault, the hanging wall moves up relative to the footwall.
Reverse faults form when rocks undergo compression, which is stress that squeezes or pushes rock together.
Reverse faults are common along convergent boundaries, where two plates collide.

17. What are the three kinds of faults?
In a strike-slip fault, the fault blocks move past each other horizontally.
Strike-slip faults form when rock is under shear stress, or stress that pushes rocks in parallel but opposite directions.
Strike-slip faults are common along transform boundaries, where tectonic plates move past each other.

20. What are the three kinds of faults?
Which kind of fault is shown in each image? What are the reasons for these faults?

23. What is Isostasy?
The earth’s lithosphere can be thought of as “floating” in gravitational balance upon the denser, deformable rocks in the asthenosphere.
To support more weight (i.e mountains) above, means you need to displace more material below.

24. What are Joints?
•Joints are fractures in rock that have not accommodated sliding. The two walls simply spread apart (open).
•They commonly occur in sedimentary rocks as vertical cracks
•Form due to cooling, tectonic stresses or weight of overlying rocks
•Joints are very important for the flow of fluids through the
ground. E.g. oil, water, etc…
•Joints are also important to consider when building things
such as roads.

25. Moving On Up What are the three kinds of mountains?
Mountains can form through
1.folding,
2.faulting, and
3.volcanism
Uplift, a process that can cause land to rise, can also contribute to mountain building. Because tectonic plates are always in motion, some mountains are constantly being uplifted.
1.Folded mountains form when rock layers are squeezed together and pushed upward. Most folded mountains form at convergent boundaries where plates collide.

26. 1.Folded mountains

27. What are the three kinds of mountains?
2.Fault-block mountains form when tension makes the lithosphere break into many normal faults.
Along the faults, some pieces of the lithosphere drop down compared with other pieces.
The pieces left standing form fault-block mountains.

28. Horst and Graben
Normal faults commonly come in pairs forming horsts and grabens.
• Horst – The part that went up (footwall blocks)
•Graben – The part that went down (hanging wall blocks).

29. What are the three kinds of mountains?
3. Volcanic mountains form when melted rock erupts onto Earth’s surface.
Many volcanic mountains are located at convergent boundaries.
Volcanic mountains can form on land or on the ocean floor.

30. What causes volcanoes to erupt?
The movement in the Earth’s plates are what causes volcanoes to form.
As the plates join or separate some of the molten rock is exposed.
Convergent plate boundaries – where two of Earth’s plates join together
Divergent plate boundaries – where two of Earth’s plates move apart RING OF FIRE!!
Hot spots – active areas below the earths crust

31. A Volcano marks a spot where there is a crack in the lithosphere.
They can form at mid-ocean ridges where plates are being pulled apart, and magma rises up. This forms volcano belts on continents and volcanic island arcs in the ocean.

32. Hot Spots on Earth
Hot spot evidence supports that the plates move over the Earth’s surface.
A hot spot is a concentration of heat in the mantle capable of producing magma, which rises to Earth’s surface.

33. Magma – the molten, or liquid-like, rock within the Earth
Structure of a Volcano
Magma – the molten, or liquid-like, rock within the Earth
Lava – magma that reaches Earth’s surface
Vent – an opening through which molten (liquid- like) rock flows onto Earth’s surface
Volcanoes always have one central vent, but can also have several smaller side vents.

34. Structure of a Volcano magma central vent side vent lava old layers
of lava
ash cloud
Earth’s crust