A geologist found a sediment deposit at the open end of a valley. After studying the deposit, the geologist concludes the sediment was deposited by the front end of a glacier. There is a glacier in the valley, but it has melted back 2.5 km up the valley (see diagram below).

How can the geologist estimate how long ago the glacier was in the lower part of the valley?
A.
Watch the glacier melt for a few hours, and see how long it takes for the distance between the glacier and the sediment deposit to double.
B.
There is no way to estimate this—the geologist must make a random guess.
C.
Divide the distance the glacier has melted back by the current rate at which it is melting back.
D.
Measure how long it takes for the rest of the glacier to melt, which will be the same amount of time.

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events in order:

1.       vishnu schist

2. zoroaster granite

3. bass limestone

4. hakatar   shale

5. igneous intrusion

6. shinumo quartzite

7. dox sandstone

8. tapeats limestone

9. bright angel shale

10. muav limestone

11. temple butte limestone

12. redwall limestone  

nonconformity

answer: the unkar group shows angular unconformity because the layers are turned at angle.

unconformity

answer: specifically the angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled. an angular unconformity occurs between the cambrian and precambrian rocks. the dox sandstone, shinumo quartzite, hakatar shale, and bass limestone have been filled.

disconformity

answer: the disconformities aremarked irregular lines between the sedimentaryrocks layers.

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