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Dive Into Oceanography with Trusted Content and Innovative Media Dive into Oceanography with Trusted Content and Innovative Media The best-selling brief book in the oceanography market combines dynamic visuals and a student-friendly narrative to bring oceanography to life and inspire students to engage and learn more about the oceans and environments around them. The 13th edition creates an interactive learning experience, providing tightly integrated text and digital offerings that make oceanography approachable and digestible for students. An emphasis on the process of science throughout the text provides students with an understanding of how scientists think and work. It also helps students develop the scientific skills of devising experiments and interpreting data. A01_TRUJ1521_13_SE_WALK.indd 1 28/11/2018 13:12 Dive into the Process of Science GraphIt! Activities are a great way to help your students develop their understanding of graphs and data. These activities use real data to help students build science literacy skills and their understanding of how to analyze and interpret graphs. 4.5 What Are the Characteristics of Cosmogenous Sediment? 125 PROCESS OF SCIENCE 4.1: extinction, large outpourings of basaltic did not reveal any K–T deposits. Evidently, When The Dinosaurs Died: volcanic rock in India (called the Deccan the impact and resulting huge waves had Traps) and other locations had occurred. stripped the ocean floor of its sediment. The Cretaceous–Tertiary Also, if there was a catastrophic meteor However, at 1600 kilometers (1000 miles) (K–T) Event impact, where was the crater? from the impact site, the telltale sediments In the early 1990s, the 190-kilometer from the catastrophe, such as the iridium- BACKGROUND (120-mile)-wide Chicxulub (pronounced rich clay layer, were preserved in sea floor The extinction of the dinosaurs—and about “SCHICK-sue-lube”) Crater off the Yu- sediments. 75% of all plant and animal species on catán coast in the Gulf of Mexico was identified as a likely candidate because NEW Process of Science Earth, including many marine species— INTERPRETING THE RESULTS occurred about 66 million years ago. This of its structure, age, and size. To create a Convincing evidence of the K–T impact extinction marks the boundary between crater this large, a 10-kilometer (6-mile)- features develop student from this and other cores collected in the Cretaceous (K) and Tertiary (T) Peri- wide object composed of rock and/or ice 2016 suggests that Earth has experienced understanding of how ods of geologic time and is known as the traveling at speeds up to 72,000 kilome- many such extraterrestrial impacts over K–T event or, because of recent changes in ters (45,000 miles) per hour must have geologic time. Statistics show that an scientists think and work. the geologic time scale, the Cretaceous– slammed into Earth (Figure 4B). Such an impact the size of the K–T event should Paleogene (K–Pg) event. Did slow climate impact would have created huge waves— Each one highlights an area occur on Earth about once every 100 mil- change lead to the extinction of these or- estimated to be more than 900 meters lion years, severely affecting life on Earth ganisms, or was it a catastrophic event? Was (3000 feet) high—that traveled throughout of oceanographic inquiry and as it did the dinosaurs. This frequency is their demise related to disease, diet, preda- the oceans. In addition, the dust and de- consistent with the fossil record, which explicitly points out the associated tion, or volcanic activity? Earth scientists bris lifted into the atmosphere most likely indicates that in the last 500 million have long sought clues to this mystery. limited photosynthesis, chilled Earth’s sur- years, Earth has experienced five major background, method, and face, and brought about the extinction of extinction events. conclusion of the inquiry. FORMING A HYPOTHESIS the dinosaurs and many other species. Fi- In 1980, geologist Walter Alvarez, his fa- nally, acid rains and global fires may have added to the environmental disaster. THINKING LIKE A SCIENTIST: ther, Nobel Physics Laureate Luis Alvarez, WHAT’S NEXT? and two nuclear chemists, Frank Asaro DEVISING AN EXPERIMENT and Helen Michel, reported that marine What kind of evidence would you expect deposits collected in northern Italy from Supporting evidence for the meteor impact to find in coastal rock sequences that NEW Process of Science the K–T boundary contained an unusual hypothesis was provided in 1997 by recov- were deposited during the time of the in Mastering. Each of the clay layer with high proportions of the me- ering cores of sediment from the sea floor. huge waves that were created by the tallic element iridium (Ir), an element rare Previous drilling close to the impact site meteor impact? new ­Process of Science features in Earth rocks but much more abundant in meteorites. The high concentrations of ­includes an assignable ­Mastering iridium suggested minerals in the clay had an extraterrestrial origin. In addition, the coaching activity to enable clay layer contained shocked quartz grains, ­students to be active participants indicating an event had occurred with enough force to fracture and partially melt and develop 21st Century Skills. pieces of quartz. Other deposits from the K–T boundary revealed similar features, supporting the hypothesis that Earth ex- perienced an extraterrestrial impact at the same time that the dinosaurs died. One problem with the impact hypoth- esis, however, is that dust spewing from volcanic eruptions on Earth could create similar clay deposits enriched in iridium and containing shocked quartz. In fact, at about the same time as the dinosaur Figure 4B The K–T meteorite impact event. A01_TRUJ1521_13_SE_WALK.indd 2 28/11/2018 13:12 M04_TRUJ1521_13_SE_C04.indd 125 22/10/2018 19:15 86 CHAPTER 3 Marine Provinces Seismic Reflection Profiles Oceanographers who want to know about ocean structure beneath the sea floor RECAP Sending pings of sound into the ocean (echo use strong low-frequency sounds produced by explosions or air guns, as shown in sounding) is a commonly used technique for determining Figure 3.7. These sounds penetrate beneath the sea floor and reflect off the bound- withocean bathymetry. Trusted More recently, satellites areContent being used to aries between and different rockDynamic or sediment layers, producing Media seismic reflection pro- map sea floor features. files, which have applications in mineral and petroleum exploration. A receiver picks up the reflected An air gun explosion emits 3 A sounds,receiver which picks upare the analyzed. reflected EXPLORING DATA ▶ Using the equation shown in Figure 3.7a, Anlow air frequencygun explosion sounds emits 1 3 sounds, which are analyzed. determine the time it takes sound to reach the deepest part of the ocean, low that frequency can penetrate sounds bottom1 sediments and rock layers. the Challenger Deep in the Mariana Trench, which is 11,022 meters that can penetrate bottom sediments and rock layers. (36,161 feet) below sea level. Use the average speed of sound in seawater of 1507 meters (4945 feet) per second. 2 The sound reflects Travel time 2 Theoff sound the boundaries reflects Depth = Speed of sound offbetween the boundaries the layers. Depth = Speed of sound Travel time2 between the layers. 2 Ocean floor OceanSoft sediment floor Rock layer A SoftFirm sediment sediment STUDENTS SOMETIMES ASK . Rock layer A F FirmRock sediment layer A Rock layer B AUL NEW Exploring Data Activities help F What happened to the 2014 Malaysian Airlines AUL Rock layer A Rock layer B T Rock layer B students engage with graphs and other Rock layer C flight that vanished after takeoff? T Rock layer B Rock layer C data-driven features to enable them to (a) A ship conducting seismic profiling. Note that depth can be determined by knowing practicet’s still a mystery. their data Malaysian interpretation Airlines flight skills. MH370 went (a) A theship speed conducting of sound seismic in seawater profiling. and Note the thattravel depth time canof the be sound. determined by knowing missing on March 8, 2014, while en route from Kuala the speed of sound in seawater and the travel time of the sound. I The process shown above reveals Lumpur, Malaysia to Beijing, China. Satellite communica- SW the structure below the sea floor. NE tions suggest that the flight veered south and ended up s.p. 1600 1700 1800 1900 Yusuf Ridge Yusuf Basin Eastern Alboran Basin running out of fuel and crash-landing in the Indian Ocean 2 west of Australia. Unfortunately, the suspected area of the Site 977 crash is large, remote, and deep, and the region’s rugged 3 sea floor is very poorly explored, all of which has hampered recovery efforts. In the days following the plane’s disappear- 4 ance, large pieces of floating trash were misidentified as Kilometers Two-way travel time (s) travel Two-way 0 5 pieces of the airplane. To this day, it’s unclear exactly what 5 happened to the airplane and all 239 people on board. An An interpretation of the seismic reflection profile shown extensive sea floor search effort by a multinational team 2 above, in which faults are shown as black lines. Site 977 from 2014–2016 found nothing and was called off in 2017. M 3 It was the world’s largest and most costly (U.S. $56 mil- M lion) marine search effort to date. In July 2015, a floating 4 piece of a wing washed up on Reunion Island in the Indian Kilometers Two-way travel time (s) travel Two-way Ocean that was later positively identified as belonging to the 5 0 5 missing plane. In 2018, a private U.S.-based team began (b) Paired seismic reflection profiles (raw above, interpreted below) of the western searching the sea floor using ship-based sonar, a small fleet Mediterranean, showing the location of JOIDES Resolution Drill Site 977.
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