Exploring Geology - Chapter 9 Investigation Table 1. Descriptions of Features Re

Question

Exploring Geology - Chapter 9 Investigation

Table 1. Descriptions of Features

Read the descriptions in the textbook for the features labeled on the figure below (Chapter 9 Investigation), and determine the order in which the features formed. At the end of the exercise, enter the letters of each feature in Table 4. From observations in nearby areas, the fault (F) occurred after units A, S, and K.

Table 2. Relative Ages of Rock Units and Sediment

Examine the six fossils in the table in the textbook, and the geologic period to which each is assigned; list the letters of all the rock units in order, from oldest to youngest. The rock units and sediments include: A, B, C, D, G, K, L, R, S, and V. If two units are the same age, draw a horizontal line joining them together in the list below. List only the rock units, not other geologic features, such as the fault. Draw a vertical line where a nonconformity, or disconformity, separates two adjacent units (except if it involves units D, L, R, and V).

Oldest _____   _____   _____   _____   _____   _____   _____   ______   _____   ____ Youngest

Table 3. Calculations of Isotopic Ages

Use these data to calculate the isotopic ages of the granite (G) and dike (D). Calculate the number of half lives that have passed and multiply this by the half life of the measured isotope.

Rock Unit

Half-Life of Isotope

# Parent Atoms

# Daughter Atoms

# of Half Lives that Have Passed

Age

Granite (G)

500 million years

125

875

Dike (D)

40 million years

500

500

Table 4. Sequence of Events

Using all the information, number the events in order from oldest to youngest.

Order (1 for oldest to 12 for youngest)

Event

____

____

____

____

____

____

____

____

____

____

____

_____

Deposition of tan sandstone (A)

Deposition of greenish shale (B)

Deposition of coarse sandstone (C)

Formation of dike (D)

Movement along fault (F)

Formation of granite (G)

Deposition of gray limestone (K)

Eruption of lava flow (L) and formation of volcano (V)

Erosion to form narrow canyon (N)

Deposition of older river gravels (R)

Deposition of reddish sandstone (S)

Development of a nonconformity on granite (not assigned a letter)

Rock Unit

Half-Life of Isotope

# Parent Atoms

# Daughter Atoms

# of Half Lives that Have Passed

Age

Granite (G)

500 million years

125

875

Dike (D)

40 million years

500

500

Explanation / Answer

here the feature description, the relative age of the rock and sequence we can understand together with the help of fundamental principles of geology like principles of superposition and cross-cutting relationship etc.

1. according to the principle of superposition which features lying at the bottom will be the oldest so here granite is the most bottom or base of all formation so we can say that oldest feature of this landscape is deposition of granite G

2. then c layer deposited over the layer G, by the principle of inclusion we can say that some particles of layer G are included in the layer C so next development after deposition of granite is Deposition of coarse sandstone (C)

3. then layer B is deposited on layer C according to the principle of superposition.

4. then layer R (Deposition of older river gravels) is deposited on the layer B  according to the principle of superposition.

5. then feature fault F takes place. we can say that according to the principle of cross-cutting relationship. because fault F cutting feature G, C, B, and R then we can say that its younger than all of them

6. then Deposition of tan sandstone (A) takes place according to the principle of superposition.

7. then river erode all the present surface and formed narrow canyon (N)

8. we can see that dike D cut the all features till A so we can say that dike is younger than all features till deposition of layer A with the help of cross-cutting relationship

9. this movement of plates may be volcano V formed on the surface and then lava eruption L takes place. we dont have a direct clear link so we are assuming here

10. then layer S deposited on the surface of A by the principle of superposition.

11 and layer K deposited on the surface of S

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