Exploring Extinction Events: Reading Assignment Quiz

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 1/16 EX Reading Assign. Quiz Started: Jan 31 at 9:27p.m. Quiz Instructions Please make sure you have read and completed the Worksheet before starting this submission. Get the Worksheet in pdf format or in docx format from the Homework (https://canvas.ubc.ca/courses/130808/modules/903620) module . This Reading Assignment Quiz is only a means of submitting your worksheet responses. This Reading Assignment explores global scale natural “disasters” or hazards, as well as objects that have impacted, or threaten to impact, our planet. We will first read and learn about the times of major extinctions and causes. Then we will access an article from a scientific journal to work through data that the authors have assembled on rates of extinctions. We will learn about the implications of these on the "sixth extinction". Finally, we will consider just one of the possible contributors to mass extinctions: meteor or asteroid impacts. 1 pts Question 1 The figure below is a “linear” geological time line presented in a circular format. You may see this or a similar depiction of geological time in class. Seven times are shown with small stars, and labelled A through G. At which of these times (i.e. which letter- labels) are each of the “big 5” extinction events?

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 2/16 Triassic–Jurassic or Tr-J E Permian–Triassic or P-Tr D Ordovician–Silurian or O-S B Late Devonian extinction or Late D C Cretaceous–Paleogene or K-Pg F 1 pts Question 2 From this figure, for roughly what proportion of Earth’s entire history did Earth experience the two periods of “snowball Earth”? 45% - 55% less than 3% 15% - 20%

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 3/16 85% - 95% 65% - 75% 25% - 30% 8% - 10% 1 pts Question 3 17 In total, how many extinction events are listed in that table? Answer with a number, NOT a word (e.g. ‘10’, not ‘ten’). 1 pts Impacts or “craters” 3 Changes in sea level, ocean chemistry or anoxia (not including “climate change” without sea-level changes) 2 Volcanic, flood basalt, magmatic provinces or “traps” events 1 Question 4 Below is a list of possible causes of extinctions that have been identified. Put these causes into order with “1” being MOST commonly identified and “3” being LEAST commonly identified. (If you need more information on one of the possible cause identified in the table, look it up!)

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1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 4/16 1 pts Question 5 What type of evidence is used to identify “extinction events”? HINT: This is NOT about evidence for how it happened but whether an “extinction event” occurred. Astronomical information such as evidence for supernovae, gamma ray bursts, etc. Geological evidence of impactors (asteroid or meteorite collisions with Earth) The fossil record Geological evidence of volcanic events Climate records (or proxies for climate variation) 1 pts Question 6 3 How many of all the extinction events (NOTE: The Great Oxygenation is not an extinction event.) in the table have at least one possible cause identified WITHOUT a reference or citation for that cause? Answer with a number, NOT a word (e.g. ‘10’, not ‘ten’). 1 pts Question 7 Rather than attributing widespread and rapid decrease in the biodiversity to a single cause, at least two types of causes seem to be necessary, each possibly including many factors. The first cause, long-term pressures on the ecosystem, called a press (one word only) by Arens and West, 2006 , make an ecosystem vulnerable. Then the second cause, a different set of more sudden changes, called a pulse (one word only), appears to tip the system into collapse.

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 5/16 1 pts Question 8 According to this short section, periods with more diverse ecosystems appear to be correlated with increasing rates at which species disappear. Also, periods with less diverse ecosystems appear to be correlated with increasing rates at which species appear. 1 pts Question 9 For which of the big 5 extinction events was the total number of genera the smallest just before the extinction? O-S Late D K-Pg Tr-J P-Tr 1 pts Question 10 What general lesson can be learned from this pair of figures by examining trends rather than the spikes representing extinction events? Earlier in time there seems to have been ______. lower diversity, and higher proportions of that diversity suffered in extinctions higher diversity, and lower proportions of that diversity suffered in extinctions

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 6/16 higher diversity, and higher proportions of that diversity suffered in extinctions lower diversity, and lower proportions of that diversity suffered in extinctions 1 pts Question 11 According to the data we are shown here, our planet suddenly lost over half of it’s marine genera ______ time(s) since 542 million years ago. 9 5 6 10 7 8 1 3 4 2 1 pts Question 12 In the abstract, the authors imply that background extinction rates are lower than their own estimate for average current rate of vertebrate species loss over the last century. If the authors had used even MORE conservative estimates for current rates of extinction, their result would have been higher than the estimate they gave.

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1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 7/16 2 pts Question 13 Regardless of model or time period, it seems that animals in group reptiles are going extinct at the “slowest” rate. The animal group with the single most alarming elevated extinction rate is amphibians , as determined using the conservative model and considering extinctions since the year 1900. Using the highly conservative model, the animal group with the most elevated rate of extinction seems to be mammals while the conservative model suggests that amphibians has the most elevated rate of extinction. 1 pts Question 14 One point of the article is to identify that, regardless of time period or model used, all these animal groups have been observed to be experiencing extinction rates that are ______ background extinction rates. much less than much more than slightly less than slightly more than similar to

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 8/16 3 pts LD average separation between au average distance between E H absolute visual magnitude (w PHA an asteroid deemed to possi NEO any object that will pass nea Albedo a measure of the proportion Question 15 Using the glossary on NASA's CNEOS website, match the terms on the column on the left to the definitions on the column on the right. 2 pts Question 16 What was the predicted date of close approach to Earth for the largest object ? Year 1918 and month September (write the name of the month) What is its estimated distance from Earth at its closest approach (minimum distance), in units of au ? 0.00234 (write the distance in units of au) Now, convert this distance to meters using the conversion factor of 1 au = 150 × 10 m. 351000000 (write the distance in units of m) 9

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 9/16 1 pts Question 17 1.16 What was this object's average estimated diameter in km? To calculate this, take the average of the minimum and maximum values given in the “Diameter” column. ______ (write the distance in units of km; watch your units!) 1 pts Question 18 13 NEOs that are estimated to be possibly 140 m in diameter or larger are considered to be potentially hazardous . Based on the list in front of you (and considering the listed maximum value of the estimated diameter), how many of these “potentially hazardous” objects are known to have passed by Earth closer than the moon in the past? 1 pts Question 19 Given the frequency-magnitude plot below, what is the minimum expected return period in years for these potentially hazardous impactors (those of at least 140 m diameter)? ______ years. Read this log-log graph carefully!

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1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 10/16 10,000 1 pts Question 20 7,500 Now use the sorting capability of this table to find the object that is predicted to have had the closest nominal distance approach to Earth of all these entries (don't change parameters, just re-sort the current table). What is this distance in km? ______ (use the conversion factor of 1 au = 150 x 10 km) 9 1 pts Question 21 Based on the data, how would you respond to a question on whether the object that had the closest nominal distance could have threatened geosynchronous

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 11/16 satellites? Choose the best answer that would keep everyone the safest. The object’s nominal Close-Approach estimate did make it a possible threat, but it was not big enough to potentially damage a satellite. Given this object’s nominal Close-Approach estimate, it was not a threat to geosynchronous satellites, regardless of its size. Not enough information to make this judgement. The object’s nominal Close-Approach estimate did make it a possible threat, AND it was big enough to potentially damage a satellite. 1 pts Question 22 Of several parameters contributing to uncertainty, which has the greatest effect on orbital uncertainty? geometry of the observations amount of time spent making observations number of observations or measurements quality of the observations (e.g. radar vs. optical) 1 pts Question 23 From paragraph 1 on that page, the NEO program estimates that they have already found over 90% of ______. all NEOs with albedo greater than 20% all visible NEOs NEOs larger than 140 m in diameter all NEOs

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 12/16 NEOs larger than 1 km in diameter 1.5 pts Question 24 Fill in each of these blanks with just a NUMBER. No words, no decimal places . From the plot, the largest number of large (>1 km diameter) NEOs was found in the year 2000 in which a total of 80 large NEOs were found. In subsequent years, counts of large NEO discoveries declined, and in the year 2022, a total of only 4 were found. 1.5 pts Question 25 Now, on the " by Survey (140 m) " page, we can see that the largest count of newly discovered NEOs 140 m or larger was in the year 2016 in which a total of 548 new NEOs in that size range were found. In comparison, the total number of NEOs in this size range discovered in, for example, the year 2022, was 455 . 1 pts Question 26 Based on these observations, it appears as if ______. most of the large (>1 km) NEOs have been found, but there are many moderate (>140 m) NEOs still to be found most of both large (>1 km) and moderate (>140 m) NEOs have already been found

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1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 13/16 there are many large (>1 km) NEOs still to be found, but most of the moderate (>140 m) NEOs have been found there are many large (>1 km) and moderate (>140 m) NEOs still to be found 1 pts Question 27 190 How many confirmed impact structures are in the Earth Impact Database? 1 pts Question 28 All of the following are reasons why we see so few craters on Earth compared to on the moon or on other solar-system bodies. However, which one do you think is the most important reason why ancient impacts from the first three quarters of Earth’s history are difficult or impossible to detect? Much of the surface is masked by vegetation and the accumulated soil it grows in. Much of Earth’s surface has been eroded. We have not yet been able to examine the entire Earth's surface with sufficient detail. Oceans are both covered in water and relatively “young” compared to continental materials. Plate tectonics has “recycled” a large portion of surface materials. 1 pts Question 29 How many impact structures, not including unknowns, are less than 10,000 years old?

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 14/16 13 1 pts Question 30 769 Given this value, what is the average time between impacts in the last 10,000 years? Approximately ______ years (use whole numbers only). 1 pts Question 31 167 What is the average time between impacts based on only those impactors that are less than 1,000 years old, not including unknowns? Approximately _____ years (use whole numbers only). 1 pts Question 32 Given these average times between impacts estimated over different time spans, which of these statements is most likely to be CORRECT? Time between impacts appears to be increasing (impactors are arriving less frequently). Time between impacts of impactors appears to be fairly constant. Time between impacts appears to be decreasing (impactors are arriving more frequently). Time between impacts appears to be increasing, but the estimates vary because older craters are harder to detect.

1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 15/16 Time between impacts appears to be decreasing, but the estimates vary because older craters are harder to detect. 1 pts Question 33 3 How many impact structures do we know of that are 2 billion years old or older? 2 pts Question 34 The crater is named Whitecourt . It is 40 meters in diameter, less than 1100 years (NOT Ma) old and and the bolide type is IIIAB iron . 1 pts Question 35 Regarding the crater closest to Edmonton, in which type of image is this crater most obvious? photograph taken in summer photograph taken in fall LiDAR image taken showing bare-earth features LiDAR image taken showing full features

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1/31/24, 9:57 PM Quiz: EX Reading Assign. Quiz https://canvas.ubc.ca/courses/130808/quizzes/702648/take 16/16 Quiz saved at 9:57pm 1 pts Question 36 What is the most likely reason why there are relatively large number of known impacts in central North America and Quebec? The surface of this region is disrupted and hidden by very active biological activity. This region has been disturbed by tectonic activity like mountain building and subduction. This region is essentially invisible from satellite imaging systems. This region is rather unpopulated. This region must have been left largely undisturbed by tectonic activity like mountain building and subduction. Submit Quiz

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