Laboratory Manual for Introductory Geology 4e

FIGURE 10.6 Block diagrams showing the contrast between nonplunging and plunging folds.
Future horizontal
erosion surface
(a) Nonplunging folds (before and after erosion).
Future horizontal
erosion surface
Fold nose
(b) Plunging folds (before and after erosion).
EXERCISE 10.5
Age Relations of Folded Strata
Name:
Course:
Section:
Date:
Refer to the block diagram below. When erosion bevels the land surface, the map surface is like a horizontal slice through
the fold. Keeping in mind that anticlines bow strata up and synclines bow them down, answer the following questions:
If resistant beds occur in the folded sequence, they form
curving ridges.
(a) Are the strata along the hinge of the anticline younger or older than the strata on the exposed part of the limbs,
as seen in the map-view surface?
(b) Are the strata along the hinge of the syncline younger or older than the strata on the exposed part of the limbs, as
seen in the map-view surface?
10.3 WORKING WITH BLOCK DIAGRAMS
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