EBK PHYSICAL UNIVERSE
15th Edition
ISBN: 9780100255036
Author: KRAUSKOPF
Publisher: YUZU
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Textbook Question
Chapter 15, Problem 30MC
The earth’s magnetic field
- a. never changes
- b. has reversed itself many times
- c. is centered exactly at the earth’s center
- d. originates in a permanently magnetized iron core
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Check out a sample textbook solutionStudents have asked these similar questions
The magnetic field of the Earth is believed to come from:
a. Solar wind.b. Solar flares.c. Iron ore deposits in the crust.d. Nickel-iron deposits in the crust.e. Convection currents within the liquid interior.
Geophysicists today generally attribute the existence of the earth’s magnetic field to…
a.
convection currents within the earth’s outer core liquid interior
b.
the earth's solid iron core
c.
iron ore deposits in the crust
d.
cosmic rays from the sun
The earth’s core is known to contain iron. Yet geologists do not regard this as a source of the earth’s magnetism. Why?
Chapter 15 Solutions
EBK PHYSICAL UNIVERSE
Ch. 15 - The most abundant element in the earths crust is...Ch. 15 - The second most abundant element is a. iron b....Ch. 15 - Minerals are a. silicon compounds b. common types...Ch. 15 - The tendency of certain minerals to split along...Ch. 15 - Feldspar is a. relatively rare in the earths crust...Ch. 15 - Quartz is a. a variety of feldspar b. a variety of...Ch. 15 - A mineral that is not a silicate is a. quartz b....Ch. 15 - The ferromagnesian minerals are usually a....Ch. 15 - Igneous rocks have been formed by a. cooling from...Ch. 15 - Rocks that have been altered by heat and pressure...
Ch. 15 - Most crustal rocks a. were formed from compacted...Ch. 15 - A general characteristic of rocks of volcanic...Ch. 15 - Foliation occurs in a. sedimentary rocks b....Ch. 15 - An example of a foliated rock is a. marble b....Ch. 15 - An example of a light-colored, coarse-grained...Ch. 15 - Limestone may be metamorphosed into a. marble b....Ch. 15 - Shale may be metamorphosed into a. marble b....Ch. 15 - Mica is present in a. marble b. chert c. basalt d....Ch. 15 - Fossils are most likely to be found in a. granite...Ch. 15 - Most earthquakes are caused by shifts of rocks...Ch. 15 - Regions in which earthquakes are frequent are also...Ch. 15 - Relative to an earthquake of magnitude 5 on the...Ch. 15 - Which one or more of the following statements...Ch. 15 - The earths crust a. has very nearly the same...Ch. 15 - The part of the earth with the greatest volume is...Ch. 15 - The radius of the earths core is roughly a. 110...Ch. 15 - The rocks of the mantle are believed to consist...Ch. 15 - Among the reasons why the earths core is believed...Ch. 15 - The chief source of the energy that powers...Ch. 15 - The earths magnetic field a. never changes b. has...Ch. 15 - If we travel around the earth, we would find that...Ch. 15 - A rock readily attacked by chemical weathering is...Ch. 15 - The principal agent of erosion is a. groundwater...Ch. 15 - Which of the following is not produced by rivers?...Ch. 15 - Glaciers produce which one or more of the...Ch. 15 - The last stage in the erosion of a river is the...Ch. 15 - Prob. 37MCCh. 15 - A fairly fast valley glacier might have a speed of...Ch. 15 - Most of the groundwater present in soil and...Ch. 15 - An aquifer is a. a river or stream on the surface...Ch. 15 - The largest amounts of sediment are deposited a....Ch. 15 - Minerals deposited by groundwater in rock fissures...Ch. 15 - Most caves are produced by the solvent action of...Ch. 15 - The chief constituent of volcanic gases is a....Ch. 15 - Prob. 45MCCh. 15 - The most common volcanic rock is a. granite b....Ch. 15 - Prob. 47MCCh. 15 - Active volcanoes are not found a. in the West...Ch. 15 - A batholith is a a. fissure from which groundwater...Ch. 15 - Arrange these elements in decreasing order of...Ch. 15 - Do silicon compounds make up less than a quarter,...Ch. 15 - What is the relationship between rocks and...Ch. 15 - What mineral is most abundant in the earths crust?...Ch. 15 - Both cleavage and crystal form are characteristic...Ch. 15 - Graphite consists of layers of carbon atoms in...Ch. 15 - In the silicate minerals each Si4+ ion is always...Ch. 15 - How could you distinguish calcite crystals from...Ch. 15 - Are the mineral grains in an igneous rock usually...Ch. 15 - Granite and rhyolite have similar compositions,...Ch. 15 - Diorite is an igneous rock that has hardened...Ch. 15 - Obsidian is a rock that resembles glass, in...Ch. 15 - In what way does calcite differ from almost all...Ch. 15 - Of what rock do coral reefs consist?Ch. 15 - What is the nature of chert and why is it so...Ch. 15 - What kind of rocks are most abundant in the earths...Ch. 15 - What happens to the density of a rock that...Ch. 15 - Why is gneiss the most abundant metamorphic rock?Ch. 15 - The mineral grains of many metamorphic rocks are...Ch. 15 - Shale is a sedimentary rock that consolidated from...Ch. 15 - (a) What is the origin of limestone? (b) What rock...Ch. 15 - Distinguish between the foliation of a metamorphic...Ch. 15 - Distinguish between quartz and quartzite.Ch. 15 - How could you distinguish (a) chert from obsidian;...Ch. 15 - How could you distinguish (a) granite from gabbro;...Ch. 15 - Name the following rocks: (a) a rock consisting of...Ch. 15 - Name the following rocks: (a) a fine-grained,...Ch. 15 - Prob. 28ECh. 15 - Each step on the Richter scale of earthquake...Ch. 15 - What can be said about an earthquake whose...Ch. 15 - Why is the mantle thought to be solid?Ch. 15 - (a) Distinguish between earthquake P and S waves....Ch. 15 - In what part of the earth does the rock motion...Ch. 15 - An earthquake occurs far from an observing station...Ch. 15 - How does the radius of the earths core compare...Ch. 15 - Where is the earths crust thinnest? Where is it...Ch. 15 - What evidence is there in favor of the idea that...Ch. 15 - What is the source of the energy that powers most...Ch. 15 - (a) Why is it believed that the earths outer core...Ch. 15 - Why does a compass needle in most places not point...Ch. 15 - Why is it unlikely that the earths magnetic field...Ch. 15 - Prob. 42ECh. 15 - Why are igneous and metamorphic rocks in general...Ch. 15 - Both marble and slate are metamorphic rocks. Would...Ch. 15 - In what way is the weathering of rock important to...Ch. 15 - Prob. 46ECh. 15 - Is there a limit to the depth to which streams can...Ch. 15 - Why are streams and rivers so effective as agents...Ch. 15 - Under what circumstances does a glacier form?Ch. 15 - Which is the more important agent of erosion...Ch. 15 - Prob. 51ECh. 15 - How is it possible for glaciers to wear down rocks...Ch. 15 - What is a water table? An aquifer?Ch. 15 - What is the immediate destination of most of the...Ch. 15 - What is the eventual site of deposition of most...Ch. 15 - Distinguish between an alluvial fan and a moraine.Ch. 15 - Why are clay minerals and quartz particles...Ch. 15 - In sand derived from the attack of waves on...Ch. 15 - What is the probable origin of the following...Ch. 15 - What characteristic landscape features do active...Ch. 15 - Prob. 61ECh. 15 - What factors determine the viscosity of a magma?...Ch. 15 - What is the cause of the holes found in many...Ch. 15 - Prob. 64ECh. 15 - (a) Why are metamorphic rocks often found near...Ch. 15 - Distinguish between a dike and a vein.
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- Volcanic and other such activity at the mid-Athletic ridge extrudes material to fill the gap between separating tectonic plates associated with continental drift. The magnetization of rocks is found to reverse in a coordinated manner with distance from the ridge. What does this imply about the Earth's magnetic field and how could the knowledge of the spreading rate he used to give its historical record?arrow_forwardThe charged currents in the outer conducting regions of the earth’s core are thought to be responsible for earth’s magnetism. What might be the ‘battery’ (i.e., the source of energy) to sustain these currents?arrow_forward1. How is magnetism similar to electricity?arrow_forward
- The magnetic north pole of the Earth is located... O in the middle of the Pacific Ocean, near the Equator. near its geographic South Pole. near its geographic North Pole. O in the middle of the Atlantic Ocean, near the Equator. O in its core.arrow_forwardII. The planet earth has a magnetic field...arrow_forwardWhich one of the following statements is true? A. The north pole of a compass needle is actually being attracted to the south geographical pole of the Earth. B. The north pole of a compass needle is actually being attracted to the north geographical pole of the Earth. C. The north pole of a compass needle is actually being attracted to the south magnetic pole of the Earth. D. The north pole of a compass needle is actually being attracted to the north magnetic pole of the Earth.arrow_forward
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