Sea Floor Spreading
1. Who proposed the idea of continental drift, which laid the foundation for seafloor spreading?
A. Isaac Newton
B. Alfred Wegener
C. Harry Hess
D. Charles Darwin
6. What pattern is observed in the magnetic properties of ocean-floor rocks?
A. Alternating stripes of reversed and normal polarity on both sides of the ridge
B. Random magnetic orientations
C. Only normal polarity on the ocean floor
D. Magnetic fields only near continents
✅ Correct Answer: A. Alternating stripes of reversed and normal polarity on both sides of the ridge
2. Who created the first accurate maps of the ocean floor using sonar technology?
A. James Cook and Robert Ballard
B. Alfred Wegener and Arthur Holmes
C. Marie Tharp and Bruce Heezen
D. Isaac Newton and Galileo Galilei
✅ Correct Answer: C. Marie Tharp and Bruce Heezen
7. Why is seafloor spreading strong evidence for plate tectonics?
A. It shows continents are shrinking
B. It shows how new ocean crust is formed and moves outward
C. It proves Earth is flat
D. It explains mountain formation only
✅ Correct Answer: B. It shows how new ocean crust is formed and moves outward
3. What is the main geological feature found along the mid-ocean ridges?
A. Deep trenches
B. Volcano arcs
C. Subduction zones
D. Upwelling magma forming new crust
✅ Correct Answer: D. Upwelling magma forming new crust
If magnetic stripes of the same polarity are found on both sides of the ridge, what does this suggest?
A. One side is older than the other
B. Both sides formed during the same magnetic period
C. The ridge is inactive
D. The crust is moving inward
✅ Correct Answer: B. Both sides formed during the same magnetic period
4. How does the age of seafloor rocks vary in relation to mid-ocean ridges?
A. They are oldest at the ridge and younger farther away
B. They are the same age everywhere
C. They are youngest at the ridge and older farther away
D. They are randomly aged
✅ Correct Answer: C. They are youngest at the ridge and older farther away
9. What is a limitation of using magnetic stripe data alone to study seafloor spreading?
A. It does not cover all oceans
B. It cannot show any age-related patterns
C. It lacks information about age and sediment thickness
D. It only applies to land crust
✅ Correct Answer: C. It lacks information about age and sediment thickness
5. How does sediment thickness change with distance from the mid-ocean ridge?
A. It becomes thinner farther from the ridge
B. It stays the same throughout
C. It becomes thicker farther from the ridge
D. It has no pattern
✅ Correct Answer: C. It becomes thicker farther from the ridge
10. What might you observe near a subduction zone instead of continuous seafloor spreading evidence?
A. New oceanic crust being formed
B. Continuous magnetic striping
C. Older crust being destroyed
D. Thick sediments and new ridges
✅ Correct Answer: C. Older crust being destroyed