Chapter 9: Planetary Geology

Question 1

What is planetary geology?

Answer 1

The science concerned with the geology of celestial bodies.

Question 2

What are seismic waves?

Answer 2

Vibrations that travel both through the interior and along the surface of a body after an earthquake.

Question 3

What is a core

Answer 3

The highest density material which resides in the the center of the body.

Question 4

What is a mantle?

Answer 4

Rocky material of of moderate density which forms a thick mantle around the core

Question 5

What is a crust?

Answer 5

The lowest density rock which forms a thin crust around the body.

Question 6

What three layers do all of the terestrial plaents have?

Answer 6

A core, a mantle, and a crust.

Question 7

What is differentiation?

Answer 7

The geological process in which denser materials are pulled to the center of a body by gravity.

Question 8

What is a lithosphere?

Answer 8

The rigid outer part of a body that consists of the crust and the upper part of the mantle.

Question 9

What is geological activity?

Answer 9

Activity that cause the surface of a world to change.

Question 10

What are the three sources of internal heat found in planets?

Answer 10

Heat of accretion, heat from differentiation, and heat from radioactive decay.

Question 11

What is heat from accretion?

Answer 11

Heat that is aquired from colliding planetesmals. During a collision, kinetic energy is converted into heat which increases the thermal energy of the planet.

Question 12

What is heat from differentiation?

Answer 12

As dense materials move towards the center of the planet, the mass loses gravitational potential energy. This energy is converted to thermal energy by friction generated as the materials separate by density.

Question 13

What is heat from radioactive decay?

Answer 13

The rock that built the terestial planets contained radioactive isotopes of elements such as uranium, potasssium, and thorium. During decay energy is relesased. Energy is also released when these particals collide with other particles, adding to the total heat of the system.

Question 14

What are the three basic processes of cooling a planet?

Answer 14

Convection, conduction, and radiation.

Question 15

What is convection?

Answer 15

The process in which hot material expands and rises while cooler material contracts and falls.

Question 16

What is conduction?

Answer 16

The transfer of heat from hot material to cooler material through contact.

Question 17

What is radiation?

Answer 17

All objects radiate themal radiation. Planets are relatively cool and therefore radiate in the infared.

Question 18

What is the most important form of heat transfer in the earth?

Answer 18

Convection.

Question 19

What are convection cells?

Answer 19

They indicate the flow of convection within the mantle of a planet.

Question 20

What is a global magnetic field?

Answer 20

A magnetic field that encompasses the earth.

Question 21

What are the three requirements for a global magnetic field?

Answer 21

1. An interior region of elctrically conducting fluid, such as molten metal
2. Convection in that layer of fluid
3. At least moderately rapid rotation

Question 22

What are the four major geological processes that shape planetary surfaces?

Answer 22

Impact cratering
Volcanism
Tectonics
Erosion

Question 23

What is impact cratering?

Answer 23

The creation of bowl-shaped impact craters by asteroids or comets striking a planet’s surface.

Question 24

What is volcanism?

Answer 24

The eruption of molten rock, or lava, from a planet’s interior onto its surface.

Question 25

What is tectonics?

Answer 25

The disruption of a planet’s surface by internal stresses

Question 26

What is erosion?

Answer 26

The wearing down or building up of geological features by wind, water,ice, and other phenomena of planetary weather.

Question 27

What is outgassing?

Answer 27

The process of a volcano releasing gas.

Question 28

Where does the majority of atmospheric gas come from?

Answer 28

Outgassing.

Question 29

What does tectonic activity go “hand in hand” with and why?

Answer 29

Volcanic activity because both require internal heat and most tectonic activity is a direct or indirect result of mantle convection.

Question 30

What caused the Lunar Maria?

Answer 30

Lava floods which filled craters and smoothed out the moon’s surface.

Question 31

Why does mercury have tremendous cliffs?

Answer 31

This is due to planetary shrinking. As mercury’s iron core cooled, it contracted. This caused the entire planet to contract by as much as 20 kilometers.

Question 32

What geological processes have shaped Mars.

Answer 32

There is evidence of all four of the main processes:

Impact Cratering, Volcanism, Tectonics, and Erosion.

Question 33

What is the main evidence for water on Mars

Answer 33

Erosion

Question 34

What is seafloor spreading?

Answer 34

The formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.

Question 35

What is seafloor crust?

Answer 35

Found on sea floor of earth. Thinner, denser, and younger than continental crust.

Question 36

What is continental crust?

Answer 36

Found on the continents of earth. Thicker, less dense, and older than seafloor crust.

Question 37

What is subduction?

Answer 37

The process where any piece of seafloor can be recycled into the mantle.

Question 38

What is a hot spot?

Answer 38

An area in which a plume of hot mantle material is rising.

Question 39

What is a fault?

Answer 39

Places where tectonic plates slip sideways relatice to each other are marked faults.