Geology: Homework #1
What is the D" layer?
A partially molten layer above the outer core at the base of the mantle.
Hypothesis
A scientist proposes that a recently discovered large ring-shaped structure is the remains of an ancient meteorite crater.
How do we know that the outer core of Earth is liquid?
A shadow zone exists where S waves do not arrive on the side of Earth opposite the focus of an earthquake.
Which of the following rocks best represents the typical composition of oceanic crust?
Basalt.
Which of the following responses best describes why the lithospheric plates are able to move around on the surface of Earth?
Because the asthenosphere is composed of weak, hot, and dense rock, the cold, rigid, less dense lithospheric plates are capable of moving on it.
The doctrine of ______ held that the major features of the surface of the earth were created by sudden, short-lived, violent events.
Catastrophism.
The layers of Earth are based on what two sets of characteristics?
Chemical composition and physical properties.
Which region of Earth is composed of abundant amounts of granite?
Continental crust.
What are the four primary zones in Earth's interior?
Crust, mantle, outer core, inner core.
Oceans cover slightly less than half of the Earth's surface.
False.
Which intellectual approach is considered the best?
Multiple working hypothesis.
What are the two types of crust?
Oceanic and continental.
The magnetic field of Earth is thought to originate in which of the following layers?
Outer core.
Why do geologists believe the inner core is solid?
P waves refract at the boundary between the outer core and inner core.
What data provided information about the existence of different zones within Earth?
P-wave and S-wave arrival times.
Which ERA contains the longest expanse of time in the geologic record?
Precambrian.
Why do we believe Earth's outer core is a liquid?
S waves do not travel through the outer core. P waves slow down and refract at the boundary between the mantle and the outer core.
Which of the following rock types is most abundant on Earth's land surface?
Sedimentary rocks.
Which of the following statements about seismic wave ray paths is most accurate?
Seismic waves move along curved ray paths because of changing properties of rocks.
How could you test whether the core of another planet were completely solid?
Set off a bomb to create seismic waves. If S waves arrive on the opposite side of the planet, then the core is solid.
The composition of the core of Earth is thought to be. . .
Solid iron-nickel alloy.
Observation
The Redwall Formation in the GrandCanyon is composed primarily of limestone.
The upper mantle can be divided into the asthenosphere and lithosphere based on what physical properties?
The asthenosphere is solid, but mobile, while the lithosphere is solid and relatively rigid.
What happens to the atmosphere as you move away from Earth's surface?
The atmosphere thins.
Which layer of Earth possesses the greatest thickness?
The mantle.
Theory
The universe originated about 13.7 billion years ago with a period of rapid expansion called the Big Bang. The outer part of the Earth consists of several large plates that move and interact with each other, thus producing earthquakes, volcanoes, and mountain ranges.
What is the major source of energy that drives the movements of the lithospheric plates on Earth?
Thermal energy from within Earth.
The Principle of ________ states that the physical, chemical, and biological processes at work shaping the Earth today have also operated in the geologic past.
Uniformitarianism.
The phrase "The present is the key to the past" describes which type of geologic thinking?
Uniformitarianism.