Problem Description:
The task is to determine the sequence of geological layers in the image from
youngest to oldest. The image shows a cross-section of rock layers, faults, and other geological features. We need to analyze the relationships between these layers and features to establish their relative ages.
---
Step-by-Step Solution:
#### 1.
Identify Key Geological Features:
-
Layers (A, B, C): These are sedimentary rock layers.
-
Faults (D): These are fractures in the rock where movement has occurred.
-
Surface (E): This represents the current ground surface.
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Water Table: Shown at the bottom of the image, indicating groundwater levels.
#### 2.
Understand the Principles of Relative Dating:
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Superposition: In undisturbed sequences, the oldest layers are at the bottom, and the youngest are at the top.
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Cross-Cutting Relationships: Faults or intrusions that cut through existing layers are younger than the layers they cut.
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Unconformities: Gaps in the rock record where erosion has removed older layers.
#### 3.
Analyze the Layers:
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Layer A: This is the topmost layer visible in the image. It is exposed at the surface (E) and is therefore the
youngest layer.
-
Layer B: This layer underlies Layer A and is continuous across much of the image. Since it is below Layer A, it is older than Layer A.
-
Layer C: This layer is found only in the lower part of the image and is beneath Layer B. It is the deepest layer shown and is therefore the
oldest.
#### 4.
Consider the Faults:
-
Fault D: The fault cuts through both Layers A and B, indicating that the faulting occurred after these layers were deposited. Therefore, the fault is younger than Layers A and B but older than the surface (E).
#### 5.
Sequence the Features:
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Youngest: Surface (E) — This is the most recent feature as it is the current ground surface.
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Next Youngest: Layer A — This is the topmost sedimentary layer.
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Next Older: Fault D — The fault cuts through Layers A and B, so it must have formed after these layers.
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Next Older: Layer B — This layer is below Layer A and above Layer C.
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Oldest: Layer C — This is the deepest layer shown in the image.
#### 6.
Final Sequence (Youngest to Oldest):
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E (Surface)
-
A
-
D (Fault)
-
B
-
C
---
Final Answer:
$$
\boxed{E, A, D, B, C}
$$
This sequence reflects the principles of superposition and cross-cutting relationships, ensuring that the relative ages of the geological features are correctly ordered.
Parent Tip: Review the logic above to help your child master the concept of relative ages of rocks worksheet.