MindTap Biology, 1 term (6 months) Printed Access Card for Starr/Taggart/Evers/Starr's Biology: The Unity and Diversity of Life (MindTap Course List)
14th Edition
ISBN: 9781305269842
Author: Cecie Starr, Ralph Taggart, Christine Evers, Lisa Starr
Publisher: Cengage Learning
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Chapter 16, Problem 1DAA
Discovery of Iridium in the K-Pg Boundary Sequence In the late 1970s, geologist Walter Alvarez was investigating the composition of the K-Pg boundary sequence in different parts of the world. He asked his father, Nobel Prize-winning physicist Luis Alvarez, to help him analyze the elemental composition of the layer. The Alvarezes and their colleagues tested the K-Pg boundary sequence in Italy and Denmark. They discovered that it contains a much higher iridium content than the surrounding rock layers. Some of their results are shown in FIGURE 16.18.
Iridium belongs to a group of elements (Appendix I) that are much more abundant in asteroids and other solar system materials than they are in Earth’s crust. The Alvarez group concluded that the K-Pg boundary sequence must have originated with extraterrestrial material. They calculated that an asteroid 14 kilometers (8.7 miles) in diameter would contain enough iridium to account for the extra iridium in the K-Pg boundary sequence.
FIGURE 18.16 Abundance of iridium in and near the K-Pg boundary sequence in Stevns Klint, Denmark. Many rock samples taken from above, below, and at the boundary were tested for iridium content. Depths are given as meters above or below the boundary.
The iridium content of an average Earth rock is 0.4 parts per billion (ppd) of iridium. An average metecrite contains about 550 parts per billion of iridium.
The photo shows Luis and Walter Alvarez with a section of the boundary sequence.
l. What was the iridium content of the K-Pg boundary sequence?
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Chapter 16 Solutions
MindTap Biology, 1 term (6 months) Printed Access Card for Starr/Taggart/Evers/Starr's Biology: The Unity and Diversity of Life (MindTap Course List)
Ch. 16 - The number of species on an island depends on the...Ch. 16 - Prob. 2SQCh. 16 - Prob. 3SQCh. 16 - A trait is adaptive if it ______. a. arises by...Ch. 16 - Prob. 5SQCh. 16 - Discovery of Iridium in the K-Pg Boundary Sequence...Ch. 16 - Prob. 2DAACh. 16 - Which of the following is a fossil? a. an insect...Ch. 16 - If the half-life of a radioisotope is 20,000...Ch. 16 - Prob. 8SQ
Ch. 16 - The dinosaurs died out ______ million years ago.Ch. 16 - On the geologic time scale, life originated in the...Ch. 16 - Prob. 11SQCh. 16 - Forces that cause geologic change include ___...Ch. 16 - Radiometric dating does not measure the age of an...Ch. 16 - If you think of geologic time spans as minutes,...
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- Discovery of Iridium in the KPg Boundary Layer In the late 1970s, geologist Walter Alvarez was investigating the composition of the KPg boundary layer in different parts of the world. He asked his father, Nobel Prizewinning physicist Luis Alvarez, to help him analyze the elemental composition of the layer. The Alvarezes and their colleagues tested the K-Pg boundary layer in Italy and Denmark, and discovered that it contains a much higher iridium content than the surrounding rode layers (FIGURE 16.17). Iridium belongs to a group of elements that are much more abundant in asteroids and other solar system materials than they are in Earths crust. The Alvarez group concluded that the KPg boundary layer must have originated with extraterrestrial material. Sample Depth Average Abundance of Iridium (ppb) +2.7m 0.3 +1.2m 0.3 +0.7m 0.36 boundary layer 41.6 0.5 m 0.25 5.4 m 0.30 FIGURE 16.17 Abundance of iridium in and near the KPg boundary layer. Iridium content of rock samples above, below, and at the KPg boundary layer in Stevns Klint, Denmark. Sample depths are given as meters above or below the layer. ppb, parts per billion. An average Earth rock contains 0.4 ppb iridium; the average meteorite, 550 ppb. The photo shows Luis and Walter Alverez next to the KPg boundary layer in Stevns Klint. How much higher was the iridium content of the boundary layer than the sample taken 0.7 meter above it?arrow_forwardDiscovery of Iridium in the KPg Boundary Layer In the late 1970s, geologist Walter Alvarez was investigating the composition of the KPg boundary layer in different parts of the world. He asked his father, Nobel Prizewinning physicist Luis Alvarez, to help him analyze the elemental composition of the layer. The Alvarezes and their colleagues tested the K-Pg boundary layer in Italy and Denmark, and discovered that it contains a much higher iridium content than the surrounding rode layers (FIGURE 16.17). Iridium belongs to a group of elements that are much more abundant in asteroids and other solar system materials than they are in Earths crust. The Alvarez group concluded that the KPg boundary layer must have originated with extraterrestrial material. Sample Depth Average Abundance of Iridium (ppb) +2.7m 0.3 +1.2m 0.3 +0.7m 0.36 boundary layer 41.6 0.5 m 0.25 5.4 m 0.30 FIGURE 16.17 Abundance of iridium in and near the KPg boundary layer. Iridium content of rock samples above, below, and at the KPg boundary layer in Stevns Klint, Denmark. Sample depths are given as meters above or below the layer. ppb, parts per billion. An average Earth rock contains 0.4 ppb iridium; the average meteorite, 550 ppb. The photo shows Luis and Walter Alverez next to the KPg boundary layer in Stevns Klint. What was the iridium content of the KPg boundary layer?arrow_forwardChanges in the Air To assess the impact of human activity on the carbon dioxide level in Earth's atmosphere, it helps to take a long view. One useful data set comes from deep core samples of Antarctic ice. The oldest ice core that has been fully analyzed dates back a bit more than 400,000 years. Air bubbles trapped in the ice provide information about the gas content in Earth's atmosphere at the time the ice formed. Combining ice core data with more recent direct measurements of atmospheric carbon dioxideas in FIGURE 46.20can help scientists put current changes in the atmospheric carbon dioxide into historical perspective. FIGURE 46.20 Changes in atmospheric carbon dioxide levels (in parts per million). Direct measurements began in 1980. Earlier data are based on ice cores. 4. Was the rise in the carbon dioxide level between 1800 and 1975 larger or smaller than the rise between 1980 and 2013?arrow_forward
- Changes in the Air To assess the impact of human activity on the carbon dioxide level in Earth's atmosphere, it helps to take a long view. One useful data set comes from deep core samples of Antarctic ice. The oldest ice core that has been fully analyzed dates back a bit more than 400,000 years. Air bubbles trapped in the ice provide information about the gas content in Earth's atmosphere at the time the ice formed. Combining ice core data with more recent direct measurements of atmospheric carbon dioxideas in FIGURE 46.20can help scientists put current changes in the atmospheric carbon dioxide into historical perspective. FIGURE 46.20 Changes in atmospheric carbon dioxide levels (in parts per million). Direct measurements began in 1980. Earlier data are based on ice cores. The industrial revolution occurred around 1800. What was the trend in carbon dioxide level in the 800 years prior to this event? What about in the 175 years after it?arrow_forwardThe heaviest elements during the Earth’s formation were what? What part of the Earth did they form? The lighter elements that formed the Earth included what? What part of the Earth did they form? Where do scientists believe the Earth’s water came from? How old was the Earth believed to be when the first stable land masses formed? What type of rock formed the first stable continents? Why is granite less dense than other rock in the mantle? The tectonic plates “float” on what layer of the Earth? Heat escaping from the Earth’s core creates what? How many tectonic plates can be identified today?arrow_forward29) The Cretaceous extinction. which was the most recent mass extinction, occurred about 65.5 million years ago. What is the leading hypothesis to explain the Cretaceous extenction? A) The Indian sub-continent collided with the Asian techtonic plate, giving rise to the Hymalayan mountains which altered the jet stream and caused the planet to enter an ice age B) An asteroid about 6 km in diameter collided with Earth, which vaporized the caribbean ocean, set fire to north and south America, and expelled enough dust into the atmosphere to block the sun enough to result in a winter like environment all across the globe for several years C) A new group of predators evolved that were significantly better at capturing prey, to the point that they drove many species (including other predators and eventually themselves) to extinction D) Massive amounts of volcanic activity released tons of CO2, enough to significantly increase the temperature of the planet 30) The Permian extinction, which…arrow_forward
- Which of the following do not provide evidence that a meteor strike was a partial cause of the Cretaceous-Paleogene mass extinction? a. A potential meteor crater off the coast of Mexico b. High layers of iridium in soil deposits in the geologic record at that time c. Shocked quartz was formed in large quantities at that time around the potential impact site d. An ozone hole appeared in the atmosphere at the time of the meteor strikearrow_forwardPart 1. Stratigraphic Dating: A Café Scene Relative dating methods establish the date of something as older or younger than something else rather than anchoring its age to an absolute, scaled timeline, as in absolute dating. So, we determine the sequence of at least two things (two events, two deposits, etc.) and establish what happened first, what happened next, and so on. In archaeology, relative dating relies on stratigraphy—what material is located above or below something else. The Law of Superposition tells us that material positioned underneath something else is usually older and material overlying a deposit is younger than the deposit, unless the layers have been disturbed. The photos that you will be shown depict a collection of items on a table: a cup, saucer, newspaper, and tickets. Imagine that these items are part of a single context such as a layer in an excavation and you want to determine whether they were deposited all at once as a single event or one after the other…arrow_forwardThe earth is about 4.6 billion years old. Based on the formation of seafloor spreading, why do you think that the oldest ocean floor is only about 200 million years old?arrow_forward
- How much more iridium was found in the K–Pg boundary layer than in rock 0.5 m below it? 41.35 ppb 41.60 ppb 41.24 ppb 39.62 ppbarrow_forwardRocks forms when lava erupts, cools, and crystallizes on Earth’s surface.arrow_forwardFact or theory? Organisms that look similar have been observed to have differences when preserved in rocks of different ages.arrow_forward
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