Chapter 1

Question 1

What led to the expanding universe theory?

Answer 1

the red shift of light from distant galaxies

Question 2

Relative Time

Answer 2

The sequence of events (what happened first, next, and so on).

Question 3

Absolute Time

Answer 3

The numerical age of events, typically measured in years.

Question 4

Doppler Effect

Answer 4

the change in frequency that you hear when a source and an observer are moving with respect to each other. When an object moves toward an observer, the waves compress (blue shift), and when it moves away, the waves stretch (red shift).

Question 5

What are the two main types of geological time?

Answer 5

Relative Time – The sequence of events (what happened first, next, and so on).
Absolute Time – The numerical age of events, typically measured in years.

Question 6

What is the lithosphere?

Answer 6

The rigid outer layer of Earth, consisting of the crust and the uppermost mantle.

Question 7

What is the asthenosphere?

Answer 7

A semi-fluid layer beneath the lithosphere, allowing tectonic plates to move.

Question 8

What is the rock cycle?

Answer 8

A model describing the processes of rock formation, breakdown, and transformation between igneous, sedimentary, and metamorphic rocks.

Question 9

What is a rock?

Answer 9

A solid made up of one or more minerals or mineraloids.

Question 10

What is mineral?

Answer 10

A naturally occurring inorganic solid with a specific chemical composition and crystalline structure.

Question 11

What are the layers of Earth based on chemical composition?

Answer 11

Crust – Silicate minerals, low density.
Mantle – Silicate minerals with more iron and magnesium.
Core – Primarily iron and nickel.

Question 12

What is the importance of Earth’s magnetic field, and how is it generated?

Answer 12

This protects Earth from harmful solar radiation and is generated by the movement of molten iron in the outer core, creating convection currents that produce a magnetic dynamo effect.

Question 13

What does the red shift of galaxies tell us about their motion with respect to Earth?

Answer 13

This indicates that galaxies are moving away from Earth, suggesting that the Universe is expanding.

Question 14

What is the Big Bang, and when did it occur?

Answer 14

The event that marks the beginning of the Universe, occurring approximately 13.8 billion years ago, when the Universe expanded from a hot, dense state.

Question 15

Describe the steps in the formation of the Solar System according to the nebular theory.

Answer 15

It explains that the Solar System formed from a rotating cloud of gas and dust. This nebula collapsed under gravity, forming the Sun in the center, with planets forming from the remaining material in a protoplanetary disk.

Question 16

Why isn’t the Earth homogeneous?

Answer 16

due to differentiation during its formation, where denser materials sank to form the core and lighter materials rose to form the crust.

Question 17

Describe how the Moon was formed.

Answer 17

The Moon likely formed from debris after a Mars-sized body collided with Earth early in its history.

Question 18

Why is the Earth round?

Answer 18

it is due to the force of gravity, which pulls matter evenly towards the center, forming a sphere.

Question 19

What is the Earth’s magnetic field, and what causes auroras?

Answer 19

caused by the interaction of solar wind with Earth’s magnetic field near the poles.

Question 20

What is Earth’s atmosphere composed of, and why would you suffocate at 12 km elevation without an oxygen tank?

Answer 20

Earth’s atmosphere is composed mostly of nitrogen (78%) and oxygen (21%). At 12 km, air pressure is too low to provide sufficient oxygen for human survival, leading to suffocation without supplemental oxygen.

Question 21

Describe the major categories of materials constituting Earth.

Answer 21

Earth’s materials include metals, silicates, and volatiles.

Question 22

How do geologists distinguish different silicate rocks?

Answer 22

Silicate rocks are distinguished based on the arrangement of their silica tetrahedra (e.g., single tetrahedra, chains, sheets).

Question 23

What are the principal layers of the Earth?

Answer 23

Earth has three main layers: the crust, the mantle, and the core (which is divided into a solid inner core and a liquid outer core).

Question 24

How do temperature and pressure change with increasing depth in the Earth?

Answer 24

Both temperature and pressure increase with depth, with the core being extremely hot and under immense pressure.

Question 25

What is Moho, and what are the differences between continental and oceanic crust?

Answer 25

The Moho is the boundary between the Earth’s crust and the mantle. Continental crust is thicker and less dense, made mostly of granite, while oceanic crust is thinner and denser, composed mainly of basalt.

Question 26

What is the mantle composed of? Is there any melt in it?

Answer 26

The mantle is composed of silicate minerals rich in magnesium and iron. While mostly solid, there is some partial melting, particularly in the asthenosphere.

Question 27

What is the core composed of?

Answer 27

The core is primarily iron and nickel.

Question 28

How do the inner and outer cores differ?

Answer 28

The outer core is liquid, and the inner core is solid.

Question 29

Which produces the magnetic field?

Answer 29

The movement of the liquid outer core generates Earth’s magnetic field.

Question 30

What is the difference between the lithosphere and asthenosphere? At what depth does their boundary occur?

Answer 30

The lithosphere is rigid, while the asthenosphere is ductile and can flow.

Question 31

Why does a galaxy’s red shift increase with distance from Earth?

Answer 31

Due to the expansion of the Universe, more distant galaxies move away faster, causing a greater red shift.

Question 32

Why are the giant planets further from the Sun?

Answer 32

Giant planets formed farther from the Sun because they contain more gas and ice, which could only condense in the colder outer regions of the early Solar System.

Question 33

Why might the Moon’s core be much smaller than Earth’s?

Answer 33

The Moon formed from material ejected after a collision, mostly from Earth’s outer layers, which have less dense materials than Earth’s core.

Question 34

Why does the Moon have virtually no magnetosphere?

Answer 34

The Moon lacks a liquid outer core, which is required to generate a significant magnetic field.

Question 35

Does the crust float on a “sea of magma”?

Answer 35

No. The mantle is mostly solid rock, although it can flow slowly over long periods of time. The “sea of magma” image is misleading.

Question 36

What is Fusion and why is it important?

Answer 36

the combining of nuclei from two lighter elements to form a new heavier element at extreme pressures and temperatures. It releases heat, which is what powers stars and it leads to the generation of new, heavier elements (nucleosynthesis).

Question 37

What is the lithosphere made of?

Answer 37

the strong, crust + upper mantle, it forms tectonic plates, has Oceanic (oceanic plate) and Continental (continental crust)

Question 38

Oceanic Rift

Answer 38

a type of divergent plate boundary where tectonic plates are moving apart beneath the ocean. As the plates separate, magma from the mantle rises to fill the gap, creating new oceanic crust. This process leads to the formation of underwater mountain ranges called mid-ocean ridges.

Question 39

Continental Drift

Answer 39

type of divergent boundary that occurs within a continental plate, where the land is being pulled apart. causes the crust to thin, stretch, and eventually fracture, creating a rift valley.

Question 40

What is seafloor spreading?

Answer 40

(1) when the crust is pulled apart, decompression of the mantle leads to melting. (2) melts move up through the mantle, then crystallize to form new oceanic crust (3) new crust records orientation of Earth’s magnetic field at the time it formed (4) Symmetric magnetic stripes are preserved on the seafloor

Question 41

What is the lower mantle, and what are its characteristics?

Answer 41

The lower mantle is the region of Earth’s mantle that extends from about 670 km to 2,900 km below the surface. It’s made of solid silicate minerals rich in magnesium and iron. It remains solid due to the immense pressure. It is denser and plays into convection i.e. plate tectonics

Question 42

Vine Matthews Hypothesis

Answer 42

there are stirps of seafloor parallel that are magnetized in opposite directions cause earth’s field has reversed itself many times

Question 43

What is the geothermal gradient?

Answer 43

The geothermal gradient is the rate at which Earth’s temperature increases with depth. On average, it increases by about 25–30°C per kilometer in the crust, though the rate can vary depending on location and depth.

Question 44

What is the nebular theory?

Answer 44

The nebular theory explains the formation of the Solar System from a cloud of gas and dust (the solar nebula). The nebula collapsed under gravity, forming a rotating disk with the Sun at the center, while the planets formed from the remaining material.

Question 45

What is a protoplanet?

Answer 45

A protoplanet is a large body in the early stages of planetary formation. Protoplanets form from the accretion of dust and gas in a protoplanetary disk, and they can eventually grow into planets through further collisions and accumulation of material.

Question 46

What is the upper mantle, and what are its characteristics?

Answer 46

The upper mantle is the layer of Earth’s mantle just below the crust, extending down to about 670 km. It is composed of solid rock but behaves plastically over long timescales, allowing for convection. It includes the lithosphere (rigid) and the asthenosphere (ductile).

Question 47

What is the transition zone in Earth’s mantle?

Answer 47

The transition zone is the area between the upper and lower mantle, located between 410 km and 670 km depth. It is characterized by abrupt changes in mineral structures due to increasing pressure, which affects the behavior of mantle materials.