Midterm 1 (Chapters 1-12)

Question 1

What is evidence that Earth is an ocean world in terms of the relationship between ocean depth and land elevation?

Answer 1

Average ocean depth is 4.5 times greater than average land elevation (height of continents above sea level).

Question 2

Define the scientific method

Answer 2

It is a systematic process of asking and answering questions about the observable world by gathering and studying data.

Question 3

List the 6 steps involved in the scientific method.

Answer 3

1. Question
2. observations and measurements
3. Hypothesis - a tentative explanation
4. Experiments- a test that controls conditions for the observation
5. Theory- a consistently supported hypothesis
6. Law- a larger construct that summarizes experimental observations

Question 4

Define Accretion, the process that forms solar systems.

Answer 4

Accretion is the process of small particles clumping into larger masses. (ex. in early Earth, heavy metals clumped together because of gravity)

Question 5

Describe the process of density stratification. (4)

Answer 5

1. The original ProtoEarth was homogenous before being bombarded by meteorites/asteroids which heated the Earth’s surface.
2. Heat and gravitational compression caused ProtoEarth to melt partially. 3. Gravity then pulled heavy metals (iron, nickel) to form the core.
3. Lighter minerals (silicon, magnesium, aluminum, oxygen-bound compounds) rose to the surface to form the Earth’s crust.

Question 6

Define the Nebular Hypothesis

Answer 6

Suggests that Earth and all the other bodies in the solar system were created by contraction of cloud gas and space dust. This is enriched by the remnants of exploded stars.

Question 7

Define density stratification

Answer 7

The process by which the Earth organizes itself in layers according to density (heaviest at the core and lightest at the crust)

Question 8

Define outgassing

Answer 8

The process by which the oceans came to the surface from inside the Earth since ProtoEarth had no oceans originally.

Question 9

Describe the process of outgassing. (4) (Occurs after density stratification)

Answer 9

1. 4.6 billion years ago, the Earth cooled and formed the surface crust.
2. Radiation from the protosun stripped away Earth’s original atmosphere.
3. Trapped gasses from inside Earth were released from excessive volcanic activity (interior of Earth started to “burp”)
4. Continued Earth cooling cause water vapour to condense into clouds which fell back to the Earth as rain and began forming the World’s oceans

Question 10

List the 4 properties of water that make it a ‘mobile stage’ for biochemical reactions needed for life.

Answer 10

1. retains heat
2. moderates temperature
3. dissolves many chemicals
4. suspends nutrients/wastes

Question 11

Definition of life

Answer 11

Consumes energy from its environment

Question 12

Why does water need to be part of a living organism?

Answer 12

Because living things need a solvent for biochemical reactions.

Question 13

List 2 reasons why oxygen is essential to life.

Answer 13

1. our bodies need oxygen to burn (oxidize) food releasing energy to our cells
2. oxygen in the form of ozone (O3) protects Earth’s surface from solar UV rays

Question 14

How does chemical and physical weathering add to the salinity of the ocean?

Answer 14

chemical weathering - dissolves minerals in rock
physical weathering - breaks down primary crystalline rock through rain or erosion that makes the rocks into smaller pieces before entering the oceans via water

Question 15

Where are stars formed and what do they spend their lives and deaths doing?

Answer 15

1. they are formed in the dusty spiral arms of galaxies
2. they spend their lives changing hydrogen and helium into heavier elements
3. they spend their deaths ejecting these heavy elements into space by cataclysmic explosions

Question 16

What factors are needed for a planet to have an ocean? (2)

Answer 16

1. Surface temperature which is determined by a planet’s distance from the sun and its rotational period (liquid water only exists between 0-100degC)
2. An atmosphere acts like a blanket blocking solar energy (without one, the Earth is -21degC)

Question 17

Where have scientists found evidence of water (other ocean worlds)?

Answer 17

1. Europa (Jupiter’s moon) - ice has broken up to look like a jigsaw puzzle suggesting an ocean lies underneath the movable crust and may also be salty
2. Titan (Saturn’s moon)- may have an ocean of hydrocarbons
3. Mars- used to have a thick CO2 atmosphere, had 3.2 billion years ago, over eons, rocks absorbed CO2 and the ocean evaporated

Question 18

Understand that the ocean began with voyaging for trade and exploration. When was the transition to scientific oceanography complete?

Answer 18

At first, people voyaged for necessity, to gain access to food supplies and to have an advantage over less skilled coastal cultures. The first evidence of voyaging comes from records of trade in the Mediterranean Sea.
- the transition was completed when the Challenger Report was completed in 1895

Question 19

Where did the systematic study of the ocean begin? What principles were invented at this library?

Answer 19

It began at the Library at Alexandria, Egypt which was founded in the 3rd century BC.

*the principles of celestial navigation were invented here

Question 20

Who is Eratosthenes of Cyrene? How did he accurately calculate the size/shape of the Earth? (what assumptions did he make)

Answer 20

Eratosthenes was the second librarian at Alexandria and the first to calculate the circumference of the Earth and also invented a system of longitude and latitude.
He used simple geometric reasoning assuming the Earth was a sphere and the sun was very far away, allowing him to calculate the circumference within 8% of its true value.

Question 21

What is the Polynesian triangle? (Polynesian colonization is an example of how ocean knowledge was used to colonize a large number of islands)

Answer 21

triangle- spreading from SE Asia/Indonesia to New Guinea and the Philippines. The mid-Pacific islands have been colonized for 2,500 years but the settlement of Hawaii occurred about A.D. 450-600 which is about 1,000 years before the Vikings discovered North America.