MOUNTAINS

FOLDED MOUNTAINS

• Formed when rock layers are squeezed together and pushed upward.
• Usually from convergent boundaries, where plates collide.
• The Appalachian mountains form from flooding and faulting when the North American plate collided with Eurasian and African plate millions of years ago.
• Today, the highest peaks are over 3,000m tall.

VOLCANIC MOUNTAINS

• Formed when melted rock erupts onto the earths surface.
• They are located at convergent boundaries.
• They can form on land or the ocean floor.
• Most of the earths active volcanoes are concentrated around the edge of the Pacific Ocean.
• This area is known as the ring of fire.

FAULT-BLOCK MOUNTAINS

• Formed when tension makes the lithosphere break into many normal faults.
• Pieces of the lithosphere drop down compared with other pieces.
• The pieces left standing form fault-block mountains.
• The Teton mountains and the Sierra Nevadans are fault-block mountains.

THREE TYPES OF FAULTS

• Normal faults
• Reverse faults
• Strike-slip faults

NORMAL FAULTS

• These faults are called normal because the blocks move in a way that you would normally exempted as a result of gravity.
• Normal faults form when under tension.
• Tension is stress that stretches or pulls rock apart.
• Normal faults come along divergent boundaries.
• The Basin and Range area of the southwestern United States is an example.

REVERSE FAULTS

• These faults are called reverse because the hanging blocks move up, which is the reverse of what you would expect as a result of gravity.
• Reverse faults form when rocks undergo compression.
• They are common on convergent boundaries, where two plates collide.
• The San Gabriel Mountains in the United States were formed by reverse faults.

TYPES OF FOLDS

• Synclines
• Anticlines

SYNCLINES

• They look like rock layers that are arched upward, like a bowl.
• Found at the core of a fold.

ANTICLINES

• They often look like rock layers that are arched downwards and high in the middle.
• Both types of folds will be visible in the same rock layers.

Mountains can be all different types. Not all mountains are the same. Every mountain is unique in its own way. Some may look similar, but not every detail is the same.