Seafloor Spreading

Question 1

Creators of Seafloor Spreading

Answer 1

Harry Hess (Geol Prof. in Princeton Uni) and Robert Dietz (Naval Reserve Rear Admiral)

Question 2

When and Why was Seafloor Spreading formed?

Answer 2

1960s - After WW2, the US navy stared mapping the seafloor

Question 3

Explain Seafloor Spreading as a “Geopoetry”

Answer 3

The theory has no supporting evidence

Question 4

What was discovered about the ocean after Seafloor Spreading was formed

Answer 4

The ocean floor is not featureless. It has ridges, trenches, etc.

Question 5

Enumerate the Seafloor Spreading Sequence (GLDS)

Answer 5

1. New oceanic crust is generated along mid-ocean ridges
2. Ocean crust spreads laterally away from the ridge crest
3. Ocean crust becomes older and denser away from the mid-ocean ridge
4. Oceanic crust is consumed along oceanic trenches

Question 6

Explain Main Evidence of Seafloor Spreading

Answer 6

Magnetic Anomalies through Paleomagnetic patterns are recorded in the seafloor. The paleomagnetic patterns show the patterns of polarity reversal

Question 7

Possible causes of Polarity Reversal (CMM)

Answer 7

1. CMB (Core Mantle Boundary) Avalanche
2. Meteorite Impact
3. Mantle Plumes

Question 8

Seafloor Mapping Findings

Answer 8

Alternating stripes of magnetically different rock laid out in rows on either side of the mid-ocean ridge

(Alternating and of normally and reversed polarized rocks) - “Magnetic Striping”

Question 9

Seafloor Spreading in a nutshell

Answer 9

ocean basins
were perpetually being “recycled,” with the creation of new crust and the destruction of old oceanic lithosphere
occurring simultaneously.

Question 10

Types of Plate Boundaries

Answer 10

Divergent, Transform, Convergent

Question 11

Divergent plate boundary features and example (OR)

Answer 11

• Oceanic ridge: Mid-Atlantic Ridge, East Pacific Rise
• Rifts: Red Sea, African Rift

Question 12

Convergent plate boundary features and examples (O-O, O-C, C-C)

Answer 12

• Oceanic-Oceanic: island arcs (PH&JPN)
• Oceanic-Continental: Mountain Range (Andes)
• Continental-Continental: Mountain Range (Himalayas)

Question 13

Some features that make Plate Tectonics a unifying concept

Answer 13

• earthquakes
• volcanoes
• mountain building
• faults and stress
• climate change
• erosion and landscape
• evolution
• mineral deposits

Question 14

Explain the unique double subduction system in the Philippines

Answer 14

PH is in between trenches, most prominently, the Philippine trench and the Manila trench. As a result, the Philippine fault occurred to accommodate the forces

Question 15

What causes plate motions and other geological features?

Answer 15

Earth’s internal heat drives mantle convection which results into plate motions, plumes, volcanoes, earthquakes, mountain ranges, and mineral deposits