GEOLOGY
PALEONTOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A layer is younger than the rocks below it and older than the rocks above it
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Any intrusion or fault is younger than the rocks it cuts through
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Geologic processes that occurred in the past are the same as those occurring today
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layers of sediment will be horizontal if unchanged
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Detailed explanation-1: -Cross-cutting relationships is a principle of geology that states that the geologic feature which cuts another is the younger of the two features.
Detailed explanation-2: -The principle of cross-cutting relationships states that a fault or intrusion is younger than the rocks that it cuts through. The fault cuts through all three sedimentary rock layers (A, B, and C) and also the intrusion (D). So the fault must be the youngest feature.
Detailed explanation-3: -Any geologic feature that crosscuts or modifies another feature must be younger than the rocks it cuts through. The cross-cutting feature is the younger feature because there must be something previously there to cross-cut. Cross-cutting features can include folds, faults, and igneous intrusions.
Detailed explanation-4: -The intrusion (D) cuts through the three sedimentary rock layers, so it must be younger than those layers. The principle of superposition states that the oldest sedimentary rock units are at the bottom, and the youngest are at the top.
Detailed explanation-5: -The principle of cross-cutting relationships states that any geological feature that cuts across, or disrupts another feature must be younger than the feature that is disrupted. An example of this is given in Figure 8.7, which shows three different sedimentary layers.