Seven Paper Models that Describe Faulting in the Earth

By Tau Rho Alpha* and John C. Lahr*

Open File Report 90-257A

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Assumptions Made in the Compilation of the Models

These paper models represent simple faults and illustrate some of the landforms associated with faulting of the Earth's crust. For scale, the models assume total displacement somewhere in the neighborhood of 40 feet or 12 meters. To make the models more realistic, some of the fault scarps are cut by gullies and are eroded in ways indicative of an arid landscape. All of the paper models show displacement on the fault by the use of arrows and by the offset of a marker bed or a stream.

• The normal and reverse fault models represent recent fault movement with no erosion. The arrows indicate the direction of relative movement, and the marker bed gives a clue as to the amount of displacement of the blocks.
• The right- and left-lateral strike-slip fault models, illustrate the occurrence of horizontal fault movement. The arrows indicate the direction of relative movement. Note the offset in the stream channels.
• On the oblique-slip fault, there has been horizontal and vertical slip on the fault line. The arrows indicate the direction of relative slip, and the marker bed gives a clue as to the amount of displacement of the blocks. The fault scarp on the upthrown block has been eroded and a stream has eroded a small canyon into this block. Note the right-lateral offset of the stream channel.
• The graben model portrays three fault blocks in which the middle block has fallen relative to the two blocks on either side. The movement on the two near-parallel faults is vertical, as indicated by the arrows. and displacement is implied by the marker bed. On one of the upthrown blocks, a stream has eroded a gully and deposited an alluvial fan.
• Three fault blocks make up the horst model with the middle block higher than the blocks on either side. The relative movement is indicated by the arrows, and the marker bed expresses the displacement of the faults. On the upthrown block (horst) there is an intermittent stream with associated gully and alluvial fan.

General Directions for Constructing the Models

To cut out the models, scissors may be used, but a small knife, such as an X-ACTO knife with a number 11 blade may be the best. For constructing the models, a water-soluble glue, preferably a stick glue, works well. Read the special instructions and study the cutting and folding steps. Look at the folding diagrams to see how the patterns fit together to make the model landforms. Make a photocopy of the pattern, carefully cut out the pattern, and fold all corners and tabs. Fold the pattern into the model before applying glue, then glue the tabs, which are indicated with a dot pattern.

By using a computer and a graphics software program (not included) geologic patterns and symbols can be added to the models before construction to represent, rock types, surface material, or the influence of man. Color can be added to the models before or after construction. Have fun customizing your three-dimensional paper fault models.

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