3/9/24, 3:15 PM Laboratory 7: Geologic Time: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts
Laboratory 7: Geologic Time
Due Mar 3 at 11:59pm
Points 14
Questions 26
Available Feb 23 at 9am - Mar 3 at 11:59pm
Time Limit None
Allowed Attempts 2
Instructions
Learning Goals
By completing this lab, students will:
Appreciate the near-eternity of geologic time.
Learn and apply relative dating techniques.
Understand how numerical dating methods work and how to interpret the data.
Apply geologic time concepts on a geologic map of Washington state.
,3/9/24, 3:15 PM Laboratory 7: Geologic Time: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts
Attempt Time Score
KEPT Attempt 2 24 minutes 14 out of 14
LATEST Attempt 2 24 minutes 14 out of 14
Attempt 1 21 minutes 12.98 out of 14
Score for this attempt: 14 out of 14
Submitted Feb 29 at 12:29pm
This attempt took 24 minutes.
Geologic processes have been active on earth since its formation 4.54 billion (4,540,000,000) years ago.
Unfortunately, evidence of early Earth is hard to come by, as older crust has been weathered and eroded
away or recycled back into the mantle through subduction processes. However, we are still able to glean
details about the Earth’s history from the geologic record. Specifically, the characteristics of the rocks
that still remain on the Earth’s surface can give us clues and insights into the Earth’s past.
Figure 7-1 Clock analogy showing earth history compressed into one hour1.
,3/9/24, 3:15 PM Laboratory 7: Geologic Time: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts
It is hard to think about geologic timescales without understanding the vastness of geologic time. While we can directly
observe some geologic processes (e.g. a volcanic eruption, an earthquake, some weathering processes), most are too slow
to be observed during human lifetimes. Furthermore, even the sheer amount of time that human beings have existed on Earth
is dwarfed by the timescales of many geologic processes (Figure 7-1). Geologists use a geologic time scale to place
geologic events in chronological order. Rock samples can be dated and placed within the geologic time scale using relative
and/or numerical dating techniques. Relative dating techniques establish the age of a rock relative to other rock samples,
while absolute dating techniques can be used to assign a more precise numerical age to a rock.
Laboratory Honor Statement
Cheating or plagiarism of any kind will not be tolerated in ESS 101. This includes copying answers from
a friend or classmate, copying answers verbatim found on the internet or other literary sources, or
copying any work that may answer the question being asked. Make sure you always use your own words
when answering the questions in the homework and cite appropriate references if you use them to help
you answer the question. Anyone caught violating the academic code of conduct
(https://www.washington.edu/cssc/for-students/academic-misconduct/) will receive a “0” grade on the
assignment, and if the conduct is deemed egregious, reported to the UW Academic Misconduct
representative.
I acknowledge that I have carefully read and understand the above statement regarding the
consequences of cheating and plagiarism, and promise to complete my work in this class with honesty
and integrity. Answer "True" below supporting your acknowledgement.
Correct!
True
False
Question 2
pts
(a) The first fossils of animals with hard parts appeared about 541 million years ago. What percentage of
geologic time does the fossil record represent? Express your answer as a percentage with two
, 3/9/24, 3:15 PM Laboratory 7: Geologic Time: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts
(b) Modern humans (Homo sapiens sapiens) appeared about 300,000 (0.3 million) years ago (Mounier
and Lahr, 2019). For what percentage of earth’s history has earth been occupied by modern humans?
Express your answer as a percentage with two significant figures. 0.0066 %
(c) The dimensions of space are somewhat analogous to the dimension of time. Consider a human hair
to conceptualize the length of earth history. The average strand of human hair is 0.1mm in width. If the
width of one human hair strand represents the duration of human occupation of earth (300,000 years),
how wide would a hair strand be that represented the duration of the earth’s history (4.54 billion years)?
Express your answer in meters using two significant figures. **Hint: Divide 0.1 mm by the percentage
you found in the previous question. This is the answer in mm. 1m = 1000 mm** 1.5
Question 3
0..25 pts
Research into geologic history depends on geological observations (like rock samples where we can
measure physical or chemical properties). If you were a geological researcher trying to study the oldest
crust on earth, where would you expect to find rock samples to support your work?
On the ocean floor because that is where new crust forms.
On the ocean floor because it has the lowest elevation.
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