Solved Topic: Relative dating of geologic events and | Chegg.com - Free Printable

Problem Description:

The image provided is a geological cross-section diagram showing various rock types, geological features, and structures. The task is to identify and explain the key geological features and processes depicted in the diagram using the provided legend.

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Solution:

#### Step 1: Understanding the Legend
The legend at the bottom of the image categorizes symbols into three groups:
1. Sedimentary Rocks: Includes Conglomerate, Gravel, Sandstone, Siltstone, Shale, Clay, Limestone, and Dolomite.
2. Igneous Rocks: Includes Granite and Basalt.
3. Metamorphic Rocks: Includes Schist and Gneiss.
4. Other Features: Includes Zone of Contact Metamorphism, Unconformity, Fault, and Contact.

#### Step 2: Analyzing the Diagram
We will analyze each labeled feature (A, B, C, D, E, F, G, H, J, K, L, M, N) in the diagram and identify what they represent based on the legend.

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Detailed Analysis of Each Feature:

1. Feature A:
- Description: This is a large intrusion of igneous rock cutting through sedimentary layers.
- Identification: Based on the pattern, it appears to be Granite (a coarse-grained igneous rock).
- Geological Process: This is an example of intrusive igneous activity, where magma cooled slowly beneath the Earth's surface, forming a plutonic body.

2. Feature B:
- Description: This is a layer of sedimentary rock at the top of the section.
- Identification: The pattern suggests it is Sandstone.
- Geological Process: Deposition of sand-sized particles over time, followed by compaction and cementation.

3. Feature C:
- Description: This is a metamorphosed rock surrounding the granite intrusion.
- Identification: The pattern indicates Schist or Gneiss.
- Geological Process: This is an example of contact metamorphism, where the heat from the granite intrusion altered the original sedimentary rocks into metamorphic rocks.

4. Feature D:
- Description: This is a layer of sedimentary rock above the granite intrusion.
- Identification: The pattern suggests it is Shale.
- Geological Process: Deposition of clay-sized particles, followed by compaction and lithification.

5. Feature E:
- Description: This is a fault line cutting through the sedimentary layers.
- Identification: The zigzag line represents a Fault.
- Geological Process: Movement along a fracture in the Earth's crust, causing displacement of rock layers.

6. Feature F:
- Description: This is a river or stream flowing over the surface.
- Identification: This is a Surface Water Feature.
- Geological Process: Erosion and transportation of sediments by water.

7. Feature G:
- Description: This is a layer of sedimentary rock below the granite intrusion.
- Identification: The pattern suggests it is Conglomerate.
- Geological Process: Deposition of rounded pebbles and cobbles, followed by compaction and cementation.

8. Feature H:
- Description: This is a zone of contact metamorphism around the granite intrusion.
- Identification: The wavy lines indicate a Zone of Contact Metamorphism.
- Geological Process: Alteration of rock properties due to heat and pressure from the granite intrusion.

9. Feature J:
- Description: This is a steeply dipping layer of sedimentary rock.
- Identification: The pattern suggests it is Limestone.
- Geological Process: Deposition of calcium carbonate-rich sediments, followed by lithification.

10. Feature K:
- Description: This is a layer of sedimentary rock above the limestone.
- Identification: The pattern suggests it is Clay.
- Geological Process: Deposition of fine clay particles, followed by compaction and lithification.

11. Feature L:
- Description: This is a layer of sedimentary rock below the conglomerate.
- Identification: The pattern suggests it is Dolomite.
- Geological Process: Deposition of calcium magnesium carbonate-rich sediments, followed by lithification.

12. Feature M:
- Description: This is a layer of sedimentary rock above the granite intrusion.
- Identification: The pattern suggests it is Gravel.
- Geological Process: Deposition of gravel-sized particles, followed by compaction and cementation.

13. Feature N:
- Description: This is a layer of sedimentary rock above the gravel.
- Identification: The pattern suggests it is Siltstone.
- Geological Process: Deposition of silt-sized particles, followed by compaction and lithification.

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Summary of Key Geological Features:

1. Intrusive Igneous Rock (Granite): Feature A represents a plutonic intrusion that caused contact metamorphism in the surrounding rocks.
2. Contact Metamorphism: Feature H shows the alteration of sedimentary rocks into metamorphic rocks due to the heat from the granite intrusion.
3. Faulting: Feature E indicates a fault line where the rock layers have been displaced.
4. Sedimentary Layers: Features B, D, G, J, K, L, M, and N represent different types of sedimentary rocks deposited over time.
5. Unconformity: There is no clear unconformity visible in this diagram, but if present, it would show a gap in the sedimentary record.

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Final Answer:

The diagram illustrates a complex geological cross-section with:
- An intrusive granite body (Feature A) causing contact metamorphism (Feature H).
- Various sedimentary layers (Features B, D, G, J, K, L, M, N) representing different depositional environments.
- A fault (Feature E) indicating tectonic movement.
- Surface water (Feature F) suggesting erosion and deposition processes.

$$
\boxed{\text{The diagram depicts a geological cross-section with intrusive igneous activity, contact metamorphism, sedimentary deposition, faulting, and surface water features.}}
$$