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Solutions Manual for Essentials of Geology, 5th Edition by Stephen Marshak (All Chapters) A+
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Solutions Manual for Essentials of Geology, 5th Edition by Stephen Marshak All Chapters 1 to 19 complete Verified editon ISBN: 9780393601107
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Solution Manual For Accompany Essentials of Geology,Marshak,5 Edition All Chapters Covered ,Latest Edition, ISBN:9780393601107
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Created by: A SolutionSolutions Manual for Essentials of Geology, 5th Edition by
Stephen Marshak (All Chapters) A+
CHAPTER 1
The Earth in Context
Learning Objectives
1. Students should be aware of the Big Bang theory. Distant galaxies are all moving away
from us. The farthest galaxies are receding from us the fastest. All matter in the Universe was
contained in a single point, approximately 13.8 billion years ago. At that time, the Universe
explosively came into existence.
2. Stars, including our Sun, are nuclear-fusion reactors. For most of their life histories (on
the order of billions of years), hydrogen atoms are fused together to form helium. Later stages in
stellar evolution include fusion of helium atoms and other, heavier elements; ultimately, iron is
the heaviest element that can be produced through fusion reactions within stars.
3. After their cycles of fusion are complete, large stars violently explode (forming
supernovas), producing elements heavier than iron and leaving behind a residue of diffuse
nebulae, which may be recycled to form a new star at some future point.
4. Our Solar System is approximately 4.57 Ga (billion years old). All eight planets revolve
around the Sun in coplanar, elliptical orbits. All planets orbit in the same direction
(counterclockwise, as viewed from above Earth’s North Pole). These facts imply simultaneous
planetary formation from a swirling nebula surrounding the Sun (the similarities in orbits would
then be a natural result of conservation of angular momentum). The planets accreted from this
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nebula through gravitational attraction and haphazard collisions. Pluto, long considered the
―ninth planet,‖ has seen its status demoted; astronomers now recognize eight major planets.
5. The terrestrial planets (Mercury, Venus, Earth, and Mars) are relatively small, dense, and
rocky worlds. The giant planets are predominantly composed of the light gases hydrogen and
helium (Jupiter and Saturn) or ices (Uranus and Neptune); they are
much larger and much less dense than the terrestrial planets.
6. Our Moon is thought to have originated from debris accumulated when a protoplanet
collided with Earth approximately 4.53 Ga.
7. The Earth System is subdivided into the atmosphere (gases and aerosols that envelop the
planet), hydrosphere (Earth’s water), geosphere (solid Earth), and biosphere (living things).
8. Earth is chemically divided into a thin, rocky crust dominated by silicate minerals, a thick
mantle composed mostly of iron- and magnesium-rich silicates (subject locally to partial
melting), and a thick, metallic core made primarily of iron (the outer portion of which is liquid).
Students should know how seismic waves tell us that the outer core must be liquid.
9. Physically, the uppermost layers of Earth are the rigid lithosphere (crust and uppermost
mantle) and the asthenosphere, which is weaker and flows plastically. The ―plates‖ of plate
tectonics theory are discrete slabs of lithosphere, which move with respect to one another atop
the asthenosphere.
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Summary from the Text
The geocentric model placed Earth at the center of the Universe. The heliocentric model placed
the Sun at the center.
The Earth is one of eight planets orbiting the Sun. The Solar System lies on the outer edge of the
Milky Way galaxy. The Universe contains hundreds of billions of galaxies.
Most astronomers agree that this expansion began after the Big Bang, a cataclysmic explosion
that occurred about 13.7 billion years ago.
The first atoms (hydrogen and helium) of the Universe developed within minutes of the Big
Bang. These atoms formed vast gas clouds, called nebulae.
Only very small atoms formed during Big Bang nucleosynthesis. The Earth, and the life forms
on it, contain elements that could have been produced only during the life cycle
of stars—intermediate-sized atoms formed by fusion during supernovae explosions. Thus, we are
all made of stardust.
Gravity caused clumps of gas in the nebulae to coalesce into flattened disks with bulbous centers.
As the central ball of this accretionary disk collapsed inward, it became a warm protostar.
Eventually, the ball became so hot and dense that fusion reactions began, and it became a true
star.
Planets developed from nebulae, the rings of gas and dust surrounding newborn stars. Matter in
these nebulae condensed into planetesimals, which then clumped together to form protoplanets,
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and finally, true planets. Inner rings became the terrestrial planets; outer rings grew into giant
planets, which consist mostly of gas and/or ice.
The Moon formed from debris ejected when a protoplanet collided with Earth in the young Solar
System.
When a protoplanet grows large enough, it eventually becomes warm enough inside to
differentiate into a core and mantle, and then to assume a near-spherical shape when it becomes
so soft that gravity can smooth out irregularities.
The Earth has a magnetic that shields it from solar wind and cosmic rays.
A layer of gas surrounds the Earth. This atmosphere, which consists of 78% N2, 21% O2, and
1% other gases, can be subdivided into layers. Air pressure decreases with increasing elevation.
The surface of Earth can be divided into land (30%) and ocean (70%). Most of the land surface
lies within 1 km of sea level. Earth’s land surface has a great variety of landscapes due to
variations in elevation and climate.
Earth materials include organic chemicals, minerals, glasses, rocks, melts, and volatiles. Most
rocks on Earth contain silica (SiO2). We distinguish among various basic rock types based on the
proportion of silica.
The Earth’s interior can be divided into three distinct layers: the very thin crust, the rocky
mantle, and the metallic core.
Pressure and temperature both increase with depth in the Earth. The rate at which temperature
increases as depth increases is the geothermal gradient.
The crust is a thin skin that varies in thickness from 7–10 km (beneath oceans) to 25–70 km
(beneath the continents). Oceanic crust is mafic in composition, whereas
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