Download QAD-Answers

Sea-Floor Spreading Answers QAD
As you read pages 104-107 use the QAD strategy as a purpose for reading.
To guide you through today’s reading:
1. Q: First rewrite the BLUE headings in the form of a question.
2. A: Read the section and answer the newly formed question.
3. D: Be sure to include some details to support and explain your answer.
Sea Floor Spreading
Q What is sea floor spreading?
A Sea floor spreading occurs when new material is
added to the Earth’s crust when the older crust is
pulled apart at a mid ocean ridge.
D
 Occurs at mid-ocean ridges
 Older material is pulled away
 New material added to ocean floor
Mid-Ocean Ridges and Sea Floor Spreading
Q What is a mid-ocean ridge?
A A mid-ocean ridge is an underwater mountain
chain.
D
 Where sea floor spreading takes place
 New oceanic lithosphere forms
 Magma rises toward the surface and solidifies
Magnetic Reversal and Sea-Floor Spreading
Q What is magnetic reversal?
A Magnetic reversal is when the poles have changes
positions over time.
D
 North and south poles have changed positions
many times
 Molten rock has many grains
 Grains align with magnetic poles
Illustrate, in color, a mid-ocean ridge, see Figure 3. Label the following:
 oceanic crust
 lithosphere

 newer crust
 asthenosphere
 older crust
 magma
where new lithosphere
form
Write a brief description of how new oceanic crust is formed. PARAPHRASE!!
Older Crust
Newer Crust
Newer Lithosphere
formation
Magma
Asthenosphere
Magma rises to the surface at a mid-ocean ridge and solidifies to form new oceanic crust.
Homework:
1. Walk around your home and observe the location of heat vents.
a. Where are the heat vents located? Be specific: name the room, at the ceiling, near the
floor, inside wall, outside wall, etc.
The heat vents are located…
2. Place your hand near the floor and describe the temperature of the air.
The temperature of the air near the floor is…
3. You will need an adult to supervise this step. Now stand on a chair and feel the air near the
ceiling. Compare the temperature at ceiling height with the air temperature near the floor.
The temperature of the air near the ceiling is _______________________________________
and the temperature of the air near the floor is _____________________________________.
a. Predict what you think causes the differing temperatures?
The differing temperatures results from…