Geologic Maps
Name:
Activity 4: A Rule for Determining Attitude (Dip) from a Map
Lab Section:
Date:
1. The relation between the dip of the unit and the surface also determines the width of an
outcrop on a map.
a. Figure 1 shows a cross section of a hill. The steeper slope on the left produces a
different outcrop pattern that than the gentler slope on the right.
Fig. 1
(1) Project the contacts from the cross section onto the map.
(2) Shade the units on the map like those in the cross section.
(3) Label each unit with its proper strike and dip symbol.
(4) Based on the map you constructed, complete the following rule explaining the
width of outcrop patterns:
For horizontal strata, gentle slopes produce
outcrop patterns,
whereas steep slopes produce
outcrop patterns.
b. Figure 2 illustrates the effect of dip on outcrop pattern.
Fig. 2
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Page 1 of 3
Geologic Maps
Activity 4: A Rule for Determining Attitude (Dip) from a Map
(1) Project the contacts from the cross section onto the map.
(2) Shade the units on the map like those in the cross section.
(3) Label each unit with its proper strike-and-dip symbol. Estimate the dips and
enter them next to the strike and dip symbols.
For horizontal surfaces, shallow dips produce
outcrop
patterns, whereas steep dips produce
outcrop patterns.
2. The two maps in Fig. 3 show the outcrop patterns of two sedimentary beds. Use them to
complete the following activity.
A
B
Fig. 3
a. For diagram A, what are the elevations of the strata at points 1 through 4?
1.
2.
3.
4.
(1) Based on this observation, the strata must be (circle one)
horizontal/vertical/inclined.
(2) Mark this strata with the proper strike-and-dip symbol in two places along its
outcrop.
b. For diagram B, what are the elevations of the strata at points 1 through 4?
1.
2.
3.
4.
(1) Based on this observation, the strata must be (circle one)
horizontal/vertical/inclined.
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Page 2 of 3
Geologic Maps
Activity 4: A Rule for Determining Attitude (Dip) from a Map
(2) Mark this strata with the proper strike-and-dip symbol in two places along its
outcrop.
The outcrop pattern of vertical beds
lines.
The outcrop pattern of horizontal beds
The outcrop pattern of inclined beds
contour
contour lines.
contour lines.
3. Using the map in Fig. 4, determine the strike and direction of dip of the shaded unit.
Place the proper strike-and-dip symbols at points A and B on the outcrop.
Fig. 4
Strike:
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Dip direction:
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