MOUNTAINS AND GEOLOGIC STRUCTURES

I. Folded Rocks

II. Faulted Rocks

III. Cause of Mountain Building

IV. Compression

V. Volcanism

VI. Warping

VII. Stretching

VIII. Hot Spots

IX. Possible Essay Questions

X. Practice Questions

I. Folded rocks -

• Anticline - An upward arch in rock layers.

• Syncline - A downward bend in rock layers.

  

  

  ANTICLINE AND SYNCLINE IN PARKING LOT AT CALICO GHOST TOWN, NEAR BARSTOW, CALIFORNIA

  

  SYNCLINE AT WEST END OF RAINBOW BASIN NATURAL AREA, NORTH OF BARSTOW, CALIFORNIA

• Dome - An upwarped circular or elongated structure.

• Basin - An downwarped circular or elongated structure.

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II. Faulted rocks -

• Normal fault - Rock material above the fault moves down in relation to the rock material below the fault.

• Reverse fault - Rock material above the fault moves up in relation to the rock material below the fault.

  

  

• Thrust fault - Reverse fault with a low inclination.

• Right-lateral fault - Movement on the fault is horizontal and rock on the opposite side moves to the right in relation to the observer.

• Left-lateral fault - Movement on the fault is horizontal and rock on the opposite side moves to the left in relation to the observer.

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III. Cause of mountain building is related to the stresses that are developed through plate interactions -

• Compression near subduction zones.

• Volcanism near subduction zones.

• Warping within plates.

• Stretching within plates.

• Volcanism over hot spots.

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IV. Compression near subduction zones produces folded mountain ranges -

• Folded mountains are mountains that consist of anticlines, synclines, and thrust faults.

• The Rocky Mountains in the west-central United States are an example of folded mountains produced by compression along an oceanic/continental plate boundary.

• The Himalayan Mountains between India and China are an example of folded mountains produced by collision along a continental/continental plate boundary.

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V. Volcanism near subduction zones produces chains of volcanoes -

• This type of volcanic chain is a mountain range that consists of numerous volcanoes that are all of relatively the same age.

• The Andes Mountains in South America are an example of a volcanic chain produced by subduction along an oceanic/continental plate boundary.

• The Aleutian Islands in Alaska are an example of a volcanic chain produced by subduction along an oceanic/oceanic plate boundary.

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VI. Warping within plates produces upwarped mountain ranges -

• Upwarped mountains consist of a single, very large, dome-shaped anticline.

• The Black Hills in South Dakota are an example.

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VII. Stretching within plates produces fault-block mountains -

• Fault-block mountains are produced by uplift along normal faults and commonly alternate with down-dropped valley blocks.

• The mountain ranges in Nevada are an example.

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VIII. Volcanism over hot spots produces chains of volcanoes -

• This type of volcanic chain is a mountain range that consists of numerous volcanoes that increase in age along the chain.

• The Hawaiian Islands are an example.

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IX. Possible essay questions -

• Describe and illustrate an anticline and a syncline.

• Describe and illustrate the five major types of faults that occur in the world.

• Describe the origin of the five major types of mountain ranges that occur in the world and give examples of each.

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X. Practice Questions

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