Laboratory 7_ Geologic Time_ ESS 101 A Wi 23_ Introduction To Geology And Societal Impacts

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3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 1/47 Laboratory 7: Geologic Time Due Mar 5 at 11:59pm Points 15 Questions 26 Available Feb 24 at 9am - Mar 5 at 11:59pm Time Limit None Allowed Attempts 2 Instructions Attempt History 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. ESS101 Lab 7: Geologic time ESS101 Lab 7: Geologic time You are allowed 2 attempts to complete this lab. A link to the PDF version of Lab 7 is provided here: Lab 7 PDF (https://canvas.uw.edu/courses/1612799/files/100033175/download)

3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 2/47 Attempt Time Score KEPT Attempt 2 24 minutes 15 out of 15 LATEST Attempt 2 24 minutes 15 out of 15 Attempt 1 54 minutes 14.83 out of 15 Score for this attempt: 15 out of 15 Submitted Mar 3 at 6:33pm 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 hour . 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 1

3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 3/47 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. http://www.extinctblog.org/extinct/2017/10/23/stop-the-clocks-and- the-other-geologic-timescale-metaphors-too (http://www.extinctblog.org/extinct/2017/10/23/stop-the-clocks-and-the-other- geologic-timescale-metaphors-too) 1 0.25 / 0.25 pts Question 1 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. True Correct! Correct!

3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 4/47 False 1 / 1 pts Question 2 Answer 1: Answer 2: (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 significant figures. 12 % (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 meters 12 Correct! Correct! 0.0066 Correct! Correct! .0066 orrect Answer orrect Answer .0065 orrect Answer orrect Answer

3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 5/47 Answer 3: 0.0065 orrect Answer orrect Answer 1.5 Correct! Correct! 0.25 / 0.25 pts Question 3 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. On a continental plate because continents are not easily subducted. Correct! Correct! On a continental plate because they have the steepest slopes.

3/3/23, 6:33 PM Laboratory 7: Geologic Time: ESS 101 A Wi 23: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1612799/quizzes/1788366 6/47 Figure 7-2: Geologic Time Scale. (Ka = Kilo-annum = thousands of years, Ma = Mega-annum millions of years, Ga = Giga-annum = billions of years) Geologists (and many other scientists who study the past) use the geologic time scale to describe different periods of earth’s history. The geologic time scale divides earth’s history into a series of chronologic subdivisions that are defined by important geologic events, such as the oxygenation of earth’s atmosphere or the evolution of different species. The names and descriptions of each type of subdivision are listed below and are included as headings in figure 7-2. Eon: eons are defined by important planetary developments in earth’s history, like the development of multicellular life. Era : each era describes a length of time with different dominant lifeforms Period : periods are defined by evolutionary changes in the fossil record Epoch: epochs are differentiated by other detectable changes in the geologic record

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