Question

ordering rock layers:

1. start at the bottom and start working your way up - the bottom has the oldest layers
2. if there is anything cutting through these layers (intrusion, fault, etc) stop counting the horizontal layers and work on that fault or intrusion
3. when you reach a point where a disturbance stops at a rock layer, that disturbance falls next in order.
4. they layer on top is always the youngest

ordering layers walkthrough

1. ______ (oldest)
2. ______
3. ______
4. ______
5. ______ (youngest)

what is letter a showing?
____________________
____________________
independent practice #1:

1. ______ (oldest)
2. ______
3. ______
4. ______
5. ______
6. ______ (youngest)

explain the events that happen in the layers of rock...
____________________
____________________
____________________
____________________
____________________
independent practice #2:

1. ______
2. ______
3. ______
4. ______
5. ______
6. ______
7. ______
8. ______
9. ______
10. ______
11. ______
12. ______

what is letter a showing?
____________________
____________________
what is letter h showing?
____________________
____________________

Explanation:

Ordering Layers Walkthrough

Step1: Identify oldest layer (bottom)

Oldest layer = M (bottommost)

Step2: Next layer above M

Next layer = F

Step3: Identify intrusion cutting M/F

Intrusion A cuts M/F, so A is younger than M/F, older than H

Step4: Layer above intrusion

Layer above A = H

Step5: Identify youngest layer (top)

Youngest layer = S (topmost)

Step6: Identify feature A

A cuts existing layers, so it's an intrusion.

Step1: Identify oldest sedimentary layer

Oldest layer = G (bottommost sedimentary)

Step2: Next layer above G

Next layer = S

Step3: Next layer above S

Next layer = M

Step4: Next layer above M

Next layer = H

Step5: Identify intrusion age

Intrusion B (36 million years) is younger than G/S/M/H, older than A

Step6: Identify youngest feature (lava flow)

Youngest feature = A (20 million years, topmost)

Step7: Explain rock layer events

List events from oldest to youngest.

Step1: Identify oldest layer (bottom)

Oldest layer = H (bottommost)

Step2: Next layer above H

Next layer = E

Step3: Next layer above E

Next layer = G

Step4: Next layer above G

Next layer = I

Step5: Next layer above I

Next layer = C

Step6: Identify intrusion cutting lower layers

Intrusion A cuts H/E/G/I/C, so A is younger than these layers

Step7: Layer formed after intrusion erosion

Layer N forms on eroded surface of A/lower layers

Step8: Next layer above N

Next layer = D

Step9: Next layer above D

Next layer = N (upper bed)

Step10: Next layer above upper N

Next layer = K

Step11: Next layer above K

Next layer = B

Step12: Identify youngest layer (top)

Youngest layer = F (topmost)

Step13: Identify features A and H

A cuts layers, H is a tilted bed.

Answer:

1. M (oldest)
2. F
3. A
4. H
5. S (youngest)

What is letter A showing? An igneous intrusion (it cuts through the older rock layers M and F, forming after them).

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Independent Practice #1