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Questions Figure 1 This figure is of a basic sequence of flat lying strata 1. Wh

ID: 112953 • Letter: Q

Question

Questions Figure 1 This figure is of a basic sequence of flat lying strata 1. Which unit is the youngest? 2. Which principle of relative time did you use to arrive at this answer? Figure 2 In this figure some of the strata have been tilted The wavy boundary represents an unconformity 3. Were the strata tilted before unit E was deposited or after? 4. Which principle of relative time did you use to arrive at this answer? Figure 3 This figure has some horizontal strata intruded by a granite body 5. In this figure is the intrusion D older or younger than unit C? 6. Which principle of relative time did you use to arrive at this answer?

Explanation / Answer

Figure 1.

1. Unit C is the youngest.

2. Principle of superposition which states that  in an undisturbed succession of sedimentary rock, the oldest layers are on the bottom thus making unit C the youngest.

Figure 2.

3. The strata were tilted before the unit E was deposited.

4. The principle of original horizonality states that most sedimentary rocks are formed as nearly horizontal layers because of gravity. Thus any layered sequences that are now tilted'or any uncomformity, were moved by later geologic processes. So unit E was deposited after the tilting reulting in it being the horizontal layer.

Figure 3.

5.Intrusion D is younger than unit C

6. Principle of inclusions. According to this principle,once a rock is lithified, no other material can be incorporated in its internal structure. So Unit D intruded the rock during the time of lithification of the rock. That means unit C was already there.